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737 | Radiocarbon_dating | The new research showed that [oxygen isotopes in foraminifera] can change | Radiocarbon dating Radiocarbon dating ( also referred to as carbon dating or carbon-14 dating ) is a method for determining the age of an object containing organic material by using the properties of radiocarbon , a radioactive isotope of carbon . The method was developed by Willard Libby in the late 1940s and soon became a standard tool for archaeologists . Libby received the Nobel Prize in Chemistry for his work in 1960 . The radiocarbon dating method is based on the fact that radiocarbon is constantly being created in the atmosphere by the interaction of cosmic rays with atmospheric nitrogen . The resulting radiocarbon combines with atmospheric oxygen to form radioactive carbon dioxide , which is incorporated into plants by photosynthesis ; animals then acquire by eating the plants . When the animal or plant dies , it stops exchanging carbon with its environment , and from that point onwards the amount of it contains begins to decrease as the undergoes radioactive decay . Measuring the amount of in a sample from a dead plant or animal such as a piece of wood or a fragment of bone provides information that can be used to calculate when the animal or plant died . The older a sample is , the less there is to be detected , and because the half-life of ( the period of time after which half of a given sample will have decayed ) is about 5,730 years , the oldest dates that can be reliably measured by this process date to around 50,000 years ago , although special preparation methods occasionally permit accurate analysis of older samples . The idea behind radiocarbon dating is straightforward , but years of work were required to develop the technique to the point where accurate dates could be obtained . Research has been ongoing since the 1960s to determine what the proportion of in the atmosphere has been over the past fifty thousand years . The resulting data , in the form of a calibration curve , is now used to convert a given measurement of radiocarbon in a sample into an estimate of the sample 's calendar age . Other corrections must be made to account for the proportion of in different types of organisms ( fractionation ) , and the varying levels of throughout the biosphere ( reservoir effects ) . Additional complications come from the burning of fossil fuels such as coal and oil , and from the above-ground nuclear tests done in the 1950s and 1960s . Because the time it takes to convert biological materials to fossil fuels is substantially longer than the time it takes for its to decay below detectable levels , fossil fuels contain almost no , and as a result there was a noticeable drop in the proportion of in the atmosphere beginning in the late 19th century . Conversely , nuclear testing increased the amount of in the atmosphere , which attained a maximum in 1963 of almost twice what it had been before the testing began . Measurement of radiocarbon was originally done by beta-counting devices , which counted the amount of beta radiation emitted by decaying atoms in a sample . More recently , accelerator mass spectrometry has become the method of choice ; it counts all the atoms in the sample and not just the few that happen to decay during the measurements ; it can therefore be used with much smaller samples ( as small as individual plant seeds ) , and gives results much more quickly . The development of radiocarbon dating has had a profound impact on archaeology . In addition to permitting more accurate dating within archaeological sites than previous methods , it allows comparison of dates of events across great distances . Histories of archaeology often refer to its impact as the `` radiocarbon revolution '' . Radiocarbon dating has allowed key transitions in prehistory to be dated , such as the end of the last ice age , and the beginning of the Neolithic and Bronze Age in different regions . |
820 | Low-carbon_economy | "Healthy societies do not fall apart over slow, widely predicted, relatively small economic adjustments of the sort painted by climate analysis. | Low-carbon economy A low-carbon economy ( LCE ) , low-fossil-fuel economy ( LFFE ) , or decarbonised economy is an economy based on low carbon power sources that therefore has a minimal output of greenhouse gas ( GHG ) emissions into the biosphere , but specifically refers to the greenhouse gas carbon dioxide . GHG emissions due to anthropogenic ( human ) activity are the dominant cause of observed global warming ( climate change ) since the mid-20th century . Continued emission of greenhouse gases will cause further warming and long-lasting changes around the world , increasing the likelihood of severe , pervasive and irreversible impacts for people and ecosystems . Many countries around the world are designing and implementing low emission development strategies ( LEDS ) . These strategies seek to achieve social , economic and environmental development goals while reducing long-term greenhouse gas emissions and increasing resilience to climate change impacts . Globally implemented low-carbon economies are therefore proposed by those having drawn this conclusion , as a means to avoid catastrophic climate change , and as a precursor to the more advanced , zero-carbon economy . |
1689 | Global_warming_controversy | Evidence is building that net cloud feedback is likely positive and unlikely to be strongly negative. | Global warming controversy The global warming controversy concerns the public debate over whether global warming is occurring , how much has occurred in modern times , what has caused it , what its effects will be , whether any action should be taken to curb it , and if so what that action should be . In the scientific literature , there is a strong consensus that global surface temperatures have increased in recent decades and that the trend is caused by human-induced emissions of greenhouse gases . No scientific body of national or international standing disagrees with this view , though a few organizations with members in extractive industries hold non-committal positions . Disputes over the key scientific facts of global warming are more prevalent in the media than in the scientific literature , where such issues are treated as resolved , and such disputes are more prevalent in the United States than globally . Political and popular debate concerning the existence and cause of climate change includes the reasons for the increase seen in the instrumental temperature record , whether the warming trend exceeds normal climatic variations , and whether human activities have contributed significantly to it . Scientists have resolved these questions decisively in favour of the view that the current warming trend exists and is ongoing , that human activity is the cause , and that it is without precedent in at least 2000 years . Public disputes that also reflect scientific debate include estimates of how responsive the climate system might be to any given level of greenhouse gases ( climate sensitivity ) , how global climate change will play out at local and regional scales , and what the consequences of global warming will be . Global warming remains an issue of widespread political debate , often split along party political lines , especially in the United States . Many of the issues that are settled within the scientific community , such as human responsibility for global warming , remain the subject of politically or economically motivated attempts to downplay , dismiss or deny them -- an ideological phenomenon categorised by academics and scientists as climate change denial . The sources of funding for those involved with climate science -- both supporting and opposing mainstream scientific positions -- have been questioned by both sides . There are debates about the best policy responses to the science , their cost-effectiveness and their urgency . Climate scientists , especially in the United States , have reported official and oil-industry pressure to censor or suppress their work and hide scientific data , with directives not to discuss the subject in public communications . Legal cases regarding global warming , its effects , and measures to reduce it have reached American courts . The fossil fuels lobby has been identified as overtly or covertly supporting efforts to undermine or discredit the scientific consensus on global warming . |
275 | Retreat_of_glaciers_since_1850 | until temperature increases began to slow down after 1998 and remained relatively stable for a period of 15 years | Retreat of glaciers since 1850 The retreat of glaciers since 1850 affects the availability of fresh water for irrigation and domestic use , mountain recreation , animals and plants that depend on glacier-melt , and , in the longer term , the level of the oceans . Studied by glaciologists , the temporal coincidence of glacier retreat with the measured increase of atmospheric greenhouse gases is often cited as an evidentiary underpinning of global warming . Mid-latitude mountain ranges such as the Himalayas , Alps , Rocky Mountains , Cascade Range , and the southern Andes , as well as isolated tropical summits such as Mount Kilimanjaro in Africa , are showing some of the largest proportionate glacial losses . Glacier mass balance is the key determinant of the health of a glacier . If the amount of frozen precipitation in the accumulation zone exceeds the quantity of glacial ice lost due to melting or in the ablation zone a glacier will advance ; if the accumulation is less than the ablation , the glacier will retreat . Glaciers in retreat will have negative mass balances , and if they do not find an equilibrium between accumulation and ablation , will eventually disappear . The Little Ice Age was a period from about 1550 to 1850 when the world experienced relatively cooler temperatures compared to the present . Subsequently , until about 1940 , glaciers around the world retreated as the climate warmed substantially . Glacial retreat slowed and even reversed temporarily , in many cases , between 1950 and 1980 as global temperatures cooled slightly . Since 1980 , a significant global warming has led to glacier retreat becoming increasingly rapid and ubiquitous , so much so that some glaciers have disappeared altogether , and the existences of many of the remaining glaciers are threatened . In locations such as the Andes of South America and Himalayas in Asia , the demise of glaciers in these regions has the potential to affect water supplies in those areas . The retreat of mountain glaciers , notably in western North America , Asia , the Alps and tropical and subtropical regions of South America , Africa and Indonesia , provide evidence for the rise in global temperatures since the late 19th century . The acceleration of the rate of retreat since 1995 of key outlet glaciers of the Greenland and West Antarctic ice sheets may foreshadow a rise in sea level , which would affect coastal regions . |
2853 | Ozone | The Ozone Layer stops UV radiation from entering our atmosphere. | Ozone Ozone -LSB- ˈoʊzoʊn -RSB- ( systematically named 1λ1 ,3 λ1-trioxidane and catena-trioxygen ) , or trioxygen , is an inorganic molecule with the chemical formula . It is a pale blue gas with a distinctively pungent smell . It is an allotrope of oxygen that is much less stable than the diatomic allotrope , breaking down in the lower atmosphere to or dioxygen . Ozone is formed from dioxygen by the action of ultraviolet light and also atmospheric electrical discharges , and is present in low concentrations throughout the Earth 's atmosphere ( stratosphere ) . In total , ozone makes up only of the atmosphere . Ozone 's odour is sharp , reminiscent of chlorine , and detectable by many people at concentrations of as little as in air . Ozone 's O3 structure was determined in 1865 . The molecule was later proven to have a bent structure and to be diamagnetic . In standard conditions , ozone is a pale blue gas that condenses at progressively cryogenic temperatures to a dark blue liquid and finally a violet-black solid . Ozone 's instability with regard to more common dioxygen is such that both concentrated gas and liquid ozone may decompose explosively at elevated temperatures or fast warming to the boiling point . It is therefore used commercially only in low concentrations . Ozone is a powerful oxidant ( far more so than dioxygen ) and has many industrial and consumer applications related to oxidation . This same high oxidising potential , however , causes ozone to damage mucous and respiratory tissues in animals , and also tissues in plants , above concentrations of about . This makes ozone a potent respiratory hazard and pollutant near ground level . However , the ozone layer ( a portion of the stratosphere with a higher concentration of ozone , from two to eight ppm ) is beneficial , preventing damaging ultraviolet light from reaching the Earth 's surface , to the benefit of both plants and animals . |
1649 | Urbanization | Urban and rural regions show the same warming trend. | Urbanization Urbanization refers to the population shift from rural to urban areas , `` the gradual increase in the proportion of people living in urban areas '' , and the ways in which each society adapts to the change . It is predominantly the process by which towns and cities are formed and become larger as more people begin living and working in central areas . The United Nations projected that half of the world 's population would live in urban areas at the end of 2008 . It is predicted that by 2050 about 64 % of the developing world and 86 % of the developed world will be urbanized . That is equivalent to approximately 3 billion urbanites by 2050 , much of which will occur in Africa and Asia . Notably , the United Nations has also recently projected that nearly all global population growth from 2017 to 2030 will be absorbed by cities , about 1.1 billion new urbanites over the next 13 years . Urbanization is relevant to a range of disciplines , including geography , sociology , economics , urban planning and public health . The phenomenon has been closely linked to modernization , industrialization and the sociological process of rationalization . Urbanization can be seen as a specific condition at a set time ( e.g. the proportion of total population or area in cities or towns ) or as an increase in that condition over time . So urbanization can be quantified either in terms of , say , the level of urban development relative to the overall population , or as the rate at which the urban proportion of the population is increasing . Urbanization creates enormous social , economic and environmental changes , which provide an opportunity for sustainability with the `` potential to use resources more efficiently , to create more sustainable land use and to protect the biodiversity of natural ecosystems . '' Urbanization is not merely a modern phenomenon , but a rapid and historic transformation of human social roots on a global scale , whereby predominantly rural culture is being rapidly replaced by predominantly urban culture . The first major change in settlement patterns was the accumulation of hunter-gatherers into villages many thousand years ago . Village culture is characterized by common bloodlines , intimate relationships and communal behavior whereas urban culture is characterized by distant bloodlines , unfamiliar relations and competitive behavior . This unprecedented movement of people is forecast to continue and intensify during the next few decades , mushrooming cities to sizes unthinkable only a century ago . Today , in Asia the urban agglomerations of Osaka , Karachi , Jakarta , Mumbai , Shanghai , Manila , Seoul and Beijing are each already home to over 20 million people , while Delhi and Tokyo are forecast to approach or exceed 40 million people each within the coming decade . Outside Asia , Mexico City , São Paulo , London , New York City , Istanbul , Lagos and Cairo are , or soon will be , home to over 10 million people . |
578 | Scientific_consensus_on_climate_change | 'If we do nothing to reduce our greenhouse gas emissions, the kind of extreme heat we saw this past summer will be the norm when my young son is a grown man.' | Scientific consensus on climate change There is currently a strong scientific consensus that the Earth is warming and that this warming is mainly caused by human activities. This consensus is supported by various studies of scientists' opinions and by position statements of scientific organizations, many of which explicitly agree with the Intergovernmental Panel on Climate Change (IPCC) synthesis reports. Nearly all actively publishing climate scientists (97–98%) support the consensus on anthropogenic climate change, and the remaining 2% of contrarian studies either cannot be replicated or contain errors. |
1943 | Human | Over 97 percent of the scientific community … believe that humans are contributing to climate change. | Human Modern humans ( Homo sapiens , primarily ssp . Homo sapiens sapiens ) are the only extant members of Hominina tribe ( or human tribe ) , a branch of the tribe Hominini belonging to the family of great apes . They are characterized by erect posture and bipedal locomotion ; high manual dexterity and heavy tool use compared to other animals ; and a general trend toward larger , more complex brains and societies . Early hominins -- particularly the australopithecines , whose brains and anatomy are in many ways more similar to ancestral non-human apes -- are less often referred to as `` human '' than hominins of the genus Homo . Several of these hominins used fire , occupied much of Eurasia , and gave rise to anatomically modern Homo sapiens in Africa about 200,000 years ago . They began to exhibit evidence of behavioral modernity around 50,000 years ago . In several waves of migration , anatomically modern humans ventured out of Africa and populated most of the world . The spread of humans and their large and increasing population has had a profound impact on large areas of the environment and millions of native species worldwide . Advantages that explain this evolutionary success include a relatively larger brain with a particularly well-developed neocortex , prefrontal cortex and temporal lobes , which enable high levels of abstract reasoning , language , problem solving , sociality , and culture through social learning . Humans use tools to a much higher degree than any other animal , are the only extant species known to build fires and cook their food , and are the only extant species to clothe themselves and create and use numerous other technologies and arts . Humans are uniquely adept at utilizing systems of symbolic communication ( such as language and art ) for self-expression and the exchange of ideas , and for organizing themselves into purposeful groups . Humans create complex social structures composed of many cooperating and competing groups , from families and kinship networks to political states . Social interactions between humans have established an extremely wide variety of values , social norms , and rituals , which together form the basis of human society . Curiosity and the human desire to understand and influence the environment and to explain and manipulate phenomena ( or events ) has provided the foundation for developing science , philosophy , mythology , religion , anthropology , and numerous other fields of knowledge . Though most of human existence has been sustained by hunting and gathering in band societies , increasing numbers of human societies began to practice sedentary agriculture approximately some 10,000 years ago , domesticating plants and animals , thus allowing for the growth of civilization . These human societies subsequently expanded in size , establishing various forms of government , religion , and culture around the world , unifying people within regions to form states and empires . The rapid advancement of scientific and medical understanding in the 19th and 20th centuries led to the development of fuel-driven technologies and increased lifespans , causing the human population to rise exponentially . Today the global human population is estimated by the United Nations to be near billion . |
363 | Desert | Monsoons in China fail, the great rivers of Asia virtually dry up, and rainfall in central America falls by half. | Desert A desert is a barren area of land where little precipitation occurs and consequently living conditions are hostile for plant and animal life . The lack of vegetation exposes the unprotected surface of the ground to the processes of denudation . About one third of the land surface of the world is arid or semi-arid . This includes much of the polar regions where little precipitation occurs and which are sometimes called polar deserts or `` cold deserts '' . Deserts can be classified by the amount of precipitation that falls , by the temperature that prevails , by the causes of desertification or by their geographical location . Deserts are formed by weathering processes as large variations in temperature between day and night put strains on the rocks which consequently break in pieces . Although rain seldom occurs in deserts , there are occasional downpours that can result in flash floods . Rain falling on hot rocks can cause them to shatter and the resulting fragments and rubble strewn over the desert floor is further eroded by the wind . This picks up particles of sand and dust and wafts them aloft in sand or dust storms . Wind-blown sand grains striking any solid object in their path can abrade the surface . Rocks are smoothed down , and the wind sorts sand into uniform deposits . The grains end up as level sheets of sand or are piled high in billowing sand dunes . Other deserts are flat , stony plains where all the fine material has been blown away and the surface consists of a mosaic of smooth stones . These areas are known as desert pavements and little further erosion takes place . Other desert features include rock outcrops , exposed bedrock and clays once deposited by flowing water . Temporary lakes may form and salt pans may be left when waters evaporate . There may be underground sources of water in the form of springs and seepages from aquifers . Where these are found , oases can occur . Plants and animals living in the desert need special adaptations to survive in the harsh environment . Plants tend to be tough and wiry with small or no leaves , water-resistant cuticles and often spines to deter herbivory . Some annual plants germinate , bloom and die in the course of a few weeks after rainfall while other long-lived plants survive for years and have deep root systems able to tap underground moisture . Animals need to keep cool and find enough food and water to survive . Many are nocturnal and stay in the shade or underground during the heat of the day . They tend to be efficient at conserving water , extracting most of their needs from their food and concentrating their urine . Some animals remain in a state of dormancy for long periods , ready to become active again when the rare rains fall . They then reproduce rapidly while conditions are favorable before returning to dormancy . People have struggled to live in deserts and the surrounding semi-arid lands for millennia . Nomads have moved their flocks and herds to wherever grazing is available and oases have provided opportunities for a more settled way of life . The cultivation of semi-arid regions encourages erosion of soil and is one of the causes of increased desertification . Desert farming is possible with the aid of irrigation and the Imperial Valley in California provides an example of how previously barren land can be made productive by the import of water from an outside source . Many trade routes have been forged across deserts , especially across the Sahara Desert , and traditionally were used by caravans of camels carrying salt , gold , ivory and other goods . Large numbers of slaves were also taken northwards across the Sahara . Some mineral extraction also takes place in deserts and the uninterrupted sunlight gives potential for the capture of large quantities of solar energy . |
538 | Atmospheric_methane | Previous studies have shown that weakening carbon sinks will add 0.25°C, forest dieback will add 0.11°C, permafrost thaw will add 0.9°C and increased bacterial respiration will add 0.02°C. | Atmospheric methane Atmospheric methane is the methane present in Earth 's atmosphere . Atmospheric methane concentrations are of interest because it is one of the most potent greenhouse gases in Earth 's atmosphere . The 100-year global warming potential of methane is 28 . That is , over a 100-year period , it traps 28 times more heat per mass unit than carbon dioxide and 32 times the effect when accounted for aerosol interactions . Global methane levels , had risen to 1800 parts per billion ( ppb ) by 2011 , an increase by a factor of 2.5 since pre-industrial times , from 722 ppb , the highest value in at least 800,000 years . Its concentration is higher in the Northern Hemisphere since most sources ( both natural and human ) are located on land and the Northern Hemisphere has more land mass . The concentrations vary seasonally , with , for example , a minimum in the northern tropics during April − May mainly due to removal by the hydroxyl radical . Early in the Earth 's history carbon dioxide and methane likely produced a greenhouse effect . The carbon dioxide would have been produced by volcanoes and the methane by early microbes . During this time , Earth 's earliest life appeared . These first , ancient bacteria added to the methane concentration by converting hydrogen and carbon dioxide into methane and water . Oxygen did not become a major part of the atmosphere until photosynthetic organisms evolved later in Earth 's history . With no oxygen , methane stayed in the atmosphere longer and at higher concentrations than it does today . Methane is created near the surface , and it is carried into the stratosphere by rising air in the tropics . Uncontrolled build-up of methane in Earth 's atmosphere is naturally checked -- although human influence can upset this natural regulation -- by methane 's reaction with hydroxyl radicals formed from singlet oxygen atoms and with water vapor . |
1998 | 2019–20_Australian_bushfire_season | There is a link between climate change and the NSW bushfires. | 2019–20 Australian bushfire season The 2019–20 Australian bushfire season, colloquially known as Black Summer, was a period of unusually intense bushfires in many parts of Australia. In June 2019, the Queensland Fire and Emergency Service acting director warned of the potential for an early start to the bushfire season which normally starts in August. The warning was based on the Northern Australia bushfire seasonal outlook noting exceptional dry conditions and a lack of soil moisture, combined with early fires in central Queensland. Throughout the summer, hundreds of fires burnt, mainly in the southeast of the country. The major fires peaked during December–January. As of 9 March 2020, the fires burnt an estimated 18.6 million hectares (46 million acres; 186,000 square kilometres; 72,000 square miles), destroyed over 5,900 buildings (including 2,779 homes) and killed at least 34 people. Nearly three billion terrestrial vertebrates alone – the vast majority being reptiles – were affected and some endangered species were believed to be driven to extinction. At its peak, air quality dropped to hazardous levels in all southern and eastern states. The cost of dealing with the bushfires is expected to exceed the A$4.4 billion of the 2009 Black Saturday fires, and tourism sector revenues fell by more than A$1 billion. However, economists estimated that the Australian bushfires may cost over A$103 billion in property damage and economic losses, making the bushfires Australia's costliest natural disaster to date. Nearly 80 percent of Australians were affected either directly or indirectly by the bushfires. By 7 January 2020, the smoke had moved approximately 11,000 kilometres (6,800 mi) across the South Pacific Ocean to Chile and Argentina. As of 2 January 2020, NASA estimated that 306 million tonnes (337 million short tons) of CO2 had been emitted.From September 2019 to March 2020, fires heavily impacted various regions of the state of New South Wales. In eastern and north-eastern Victoria large areas of forest burnt out of control for four weeks before the fires emerged from the forests in late December. Multiple states of emergency were declared across New South Wales, Victoria, and the Australian Capital Territory. Reinforcements from all over Australia were called in to assist fighting the fires and relieve exhausted local crews in New South Wales. The Australian Defence Force was mobilised to provide air support to the firefighting effort and to provide manpower and logistical support. Firefighters, supplies and equipment from Canada, New Zealand, Singapore and the United States, among others, helped fight the fires, especially in New South Wales.During the ensuing crisis, an air tanker and two helicopters crashed during firefighting operations, the air tanker crash resulting in the deaths of the three crew. Two fire trucks were caught in fatal incidents caused directly by fire conditions, killing three fire fighters.By 4 March 2020, all fires in New South Wales had been extinguished completely (to the point where there were no fires in the state for the first time since July 2019), and the Victoria fires had all been contained. The last fire of the season occurred in Lake Clifton, Western Australia, in early May.There has been considerable debate regarding the underlying cause of the intensity and scale of the fires, including the role of fire management practices and climate change, which during the peak of the crisis attracted significant international attention. Politicians visiting fire impacted areas received mixed responses, in particular Prime Minister Scott Morrison. An estimated A$500 million was donated by the public at large, international organisations, public figures and celebrities for victim relief and wildlife recovery. Convoys of donated food, clothing and livestock feed were sent to affected areas. |
1683 | Global_warming_hiatus | The PDO shows no trend, and therefore the PDO is not responsible for the trend of global warming. | Global warming hiatus A global warming hiatus , also sometimes referred to as a global warming pause or a global warming slowdown , is a period of relatively little change in globally averaged surface temperatures . In the current episode of global warming many such 15-year periods appear in the surface temperature record , along with robust evidence of the long-term warming trend ; climate is classically averaged over 30-year periods . Publicity has surrounded claims of a global warming hiatus during the period 1998 -- 2013 . The exceptionally warm El Niño year of 1998 was an outlier from the continuing temperature trend , and so subsequent annual temperatures gave the appearance of a hiatus : by January 2006 , it appeared to some that global warming had stopped or paused . A 2009 study showed that decades without warming were not exceptional , and in 2011 a study showed that if allowances were made for known variability , the rising temperature trend continued unabated . There was increased public interest in 2013 in the run-up to publication of the IPCC Fifth Assessment Report , and despite concerns that a 15-year period was too short to determine a meaningful trend , the IPCC included a section on a hiatus , which it defined as a much smaller increasing linear trend over the 15 years from 1998 to 2012 , than over the 60 years from 1951 to 2012 . Various studies examined possible causes of the short-term slowdown . Even though the overall climate system has continued to accumulate energy due to Earth 's positive energy budget , the available temperature readings at the Earth 's surface indicate slower rates of increase in surface warming than in the prior decade . Since measurements at the top of the atmosphere show that Earth is receiving more energy than it is radiating back into space , the retained energy should be producing warming in the Earth 's climate system . Research reported in July 2015 on an updated NOAA dataset casts doubt on the existence of a hiatus , and it finds no indication of a slowdown even in earlier years . Scientists working on other datasets welcomed this study , though they have expressed the view that the recent warming trend was less than in previous periods of the same length . Subsequently , a detailed study supports the conclusion that warming is continuing , but it also find there was less warming between 2001 and 2010 than climate models had predicted , and that this slowdown might be attributed to short-term variations in the Pacific decadal oscillation ( PDO ) , which was negative during that period . Another review finds `` no substantive evidence '' of a pause in global warming . A statistical study of global temperature data since 1970 concludes that the term ` hiatus ' or ` pause ' is not justified . Independent of these discussions about data and measurements for earlier years , 2015 turned out to be much warmer than any of the earlier years , already before El Niño conditions started . The warmth of 2015 largely ended any remaining scientific credibility of claims that the supposed `` hiatus '' since 1998 had any significance for the long-term warming trend . In January 2017 , a study published in the journal Science Advances cast further doubt on the existence of a recent pause , with more evidence that ocean temperatures have been underestimated . An April 2017 study found the data consistent with a steady warming trend globally since the 1970s , with fluctuations within the expected range of short term variability . |
3093 | Microwave | Sending oscillating microwaves from an antenna inside a vacuum through an electromagnetic field through a dielectric material, such as water, creates radio frequency heating at the molecular level | Microwave Microwaves are a form of electromagnetic radiation with wavelengths ranging from one meter to one millimeter ; with frequencies between 300 MHz and 300 GHz . Different sources define different frequency ranges as microwaves ; the above broad definition includes both UHF and EHF ( millimeter wave ) bands . A more common definition in radio engineering is the range between 1 and 100 GHz ( 300 and 3 mm ) . In all cases , microwaves include the entire SHF band ( 3 to 30 GHz , or 10 to 1 cm ) at minimum . Frequencies in the microwave range are often referred to by their IEEE radar band designations : S , C , X , Ku , K , or Ka band , or by similar NATO or EU designations . The prefix in microwave is not meant to suggest a wavelength in the micrometer range . It indicates that microwaves are `` small '' , compared to the radio waves used prior to microwave technology , in that they have shorter wavelengths . The boundaries between far infrared , terahertz radiation , microwaves , and ultra-high-frequency radio waves are fairly arbitrary and are used variously between different fields of study . Microwaves travel by line-of-sight ; unlike lower frequency radio waves they do not diffract around hills , follow the earth 's surface as ground waves , or reflect from the ionosphere , so terrestrial microwave communication links are limited by the visual horizon to about 40 miles ( 64 km ) . At the high end of the band they are absorbed by gases in the atmosphere , limiting practical communication distances to around a kilometer . Microwaves are extremely widely used in modern technology . They are used for point-to-point communication links , wireless networks , microwave radio relay networks , radar , satellite and spacecraft communication , medical diathermy and cancer treatment , remote sensing , radio astronomy , particle accelerators , spectroscopy , industrial heating , collision avoidance systems , garage door openers and keyless entry systems , and for cooking food in microwave ovens . |
2256 | Climate_change_feedback | The warming effect from more CO2 greatly outstrips the influence from changes in the Earth's orbit or solar activity, even if solar levels were to drop to Maunder Minimum levels. | Climate change feedback Climate change feedback is important in the understanding of global warming because feedback processes may amplify or diminish the effect of each climate forcing , and so play an important part in determining the climate sensitivity and future climate state . Feedback in general is the process in which changing one quantity changes a second quantity , and the change in the second quantity in turn changes the first . Positive feedback amplifies the change in the first quantity while negative feedback reduces it . The term `` forcing '' means a change which may `` push '' the climate system in the direction of warming or cooling . An example of a climate forcing is increased atmospheric concentrations of greenhouse gases . By definition , forcings are external to the climate system while feedbacks are internal ; in essence , feedbacks represent the internal processes of the system . Some feedbacks may act in relative isolation to the rest of the climate system ; others may be tightly coupled ; hence it may be difficult to tell just how much a particular process contributes . Forcings , feedbacks and the dynamics of the climate system determine how much and how fast the climate changes . The main positive feedback in global warming is the tendency of warming to increase the amount of water vapor in the atmosphere , which in turn leads to further warming . The main negative feedback comes from the Stefan -- Boltzmann law , the amount of heat radiated from the Earth into space changes with the fourth power of the temperature of Earth 's surface and atmosphere . Some observed and potential effects of global warming are positive feedbacks , which contribute directly to further global warming . The Intergovernmental Panel on Climate Change 's ( IPCC ) Fourth Assessment Report states that `` Anthropogenic warming could lead to some effects that are abrupt or irreversible , depending upon the rate and magnitude of the climate change . '' |
2106 | Global_warming | Scientists tried to 'hide the decline' in global temperature | Global warming Global warming , also referred to as climate change , is the observed century-scale rise in the average temperature of the Earth 's climate system and its related effects . Multiple lines of scientific evidence show that the climate system is warming . Many of the observed changes since the 1950s are unprecedented in the instrumental temperature record which extends back to the mid 19th century , and in paleoclimate proxy records over thousands of years . In 2013 , the Intergovernmental Panel on Climate Change ( IPCC ) Fifth Assessment Report concluded that `` It is extremely likely that human influence has been the dominant cause of the observed warming since the mid-20th century . '' The largest human influence has been emission of greenhouse gases such as carbon dioxide , methane and nitrous oxide . Climate model projections summarized in the report indicated that during the 21st century the global surface temperature is likely to rise a further 0.3 to for their lowest emissions scenario and 2.6 to for the highest emissions scenario . These findings have been recognized by the national science academies of the major industrialized nations and are not disputed by any scientific body of national or international standing . Future climate change and associated impacts will differ from region to region around the globe . Anticipated effects include warming global temperature , rising sea levels , changing precipitation , and expansion of deserts in the subtropics . Warming is expected to be greater over land than over the oceans and greatest in the Arctic , with the continuing retreat of glaciers , permafrost and sea ice . Other likely changes include more frequent extreme weather events including heat waves , droughts , heavy rainfall with floods and heavy snowfall ; ocean acidification ; and species extinctions due to shifting temperature regimes . Effects significant to humans include the threat to food security from decreasing crop yields and the abandonment of populated areas due to rising sea levels . Because the climate system has a large `` inertia '' and greenhouse gases will stay in the atmosphere for a long time , many of these effects will not only exist for decades or centuries , but will persist for tens of thousands of years . Possible societal responses to global warming include mitigation by emissions reduction , adaptation to its effects , building systems resilient to its effects , and possible future climate engineering . Most countries are parties to the United Nations Framework Convention on Climate Change ( UNFCCC ) , whose ultimate objective is to prevent dangerous anthropogenic climate change . Parties to the UNFCCC have agreed that deep cuts in emissions are required and that global warming should be limited to well below 2.0 C-change relative to pre-industrial levels , with efforts made to limit warming to 1.5 C-change . Public reactions to global warming and concern about its effects are also increasing . A global 2015 Pew Research Center report showed a median of 54 % consider it `` a very serious problem '' . There are significant regional differences , with Americans and Chinese ( whose economies are responsible for the greatest annual CO2 emissions ) among the least concerned . |
2843 | Sea_level_rise | Together, these two unaltered [sea level] datasets indicate that global mean sea level trend has remained stable over the entire period 1992-2007, altogether eliminating the apparent 3.2 mm/year rate of sea-level rise arising from the "adjusted" data. | Sea level rise A sea level rise is an increase in the volume of water in the world 's oceans , resulting in an increase in global mean sea level . Sea level rise is usually attributed to global climate change by thermal expansion of the water in the oceans and by melting of Ice sheets and glaciers on land . Melting of floating ice shelves or icebergs at sea raises sea levels only slightly . Sea level rise at specific locations may be more or less than the global average . Local factors might include tectonic effects , subsidence of the land , tides , currents , storms , etc. . Sea level rise is expected to continue for centuries . Because of the slow inertia , long response time for parts of the climate system , it has been estimated that we are already committed to a sea-level rise of approximately 2.3 m for each degree Celsius of temperature rise within the next 2,000 years . IPCC Summary for Policymakers , AR5 , 2014 , indicated that the global mean sea level rise will continue during the 21st century , very likely at a faster rate than observed from 1971 to 2010 . Projected rates and amounts vary . A January 2017 NOAA report suggests a range of GMSL rise of 0.3 -- 2.5 m possible during the 21st century . Sea level rises can considerably influence human populations in coastal and island regions and natural environments like marine ecosystems . |
820 | Economic_growth | "Healthy societies do not fall apart over slow, widely predicted, relatively small economic adjustments of the sort painted by climate analysis. | Economic growth Economic growth is the increase in the inflation-adjusted market value of the goods and services produced by an economy over time . It is conventionally measured as the percent rate of increase in real gross domestic product , or real GDP , usually in per capita terms . Growth is usually calculated in real terms -- i.e. , inflation-adjusted terms -- to eliminate the distorting effect of inflation on the price of goods produced . Measurement of economic growth uses national income accounting . Since economic growth is measured as the annual percent change of gross domestic product ( GDP ) , it has all the advantages and drawbacks of that measure . The `` rate of economic growth '' refers to the geometric annual rate of growth in GDP between the first and the last year over a period of time . Implicitly , this growth rate is the trend in the average level of GDP over the period , which implicitly ignores the fluctuations in the GDP around this trend . An increase in economic growth caused by more efficient use of inputs ( such as labor productivity , physical capital , energy or materials ) is referred to as intensive growth . GDP growth caused only by increases in the amount of inputs available for use ( increased population , new territory ) is called extensive growth . |
2790 | Global_warming | That model predicted that global temperature between 1988 and 1997 would rise by 0.45°C (Figure 1). | Global warming Global warming , also referred to as climate change , is the observed century-scale rise in the average temperature of the Earth 's climate system and its related effects . Multiple lines of scientific evidence show that the climate system is warming . Many of the observed changes since the 1950s are unprecedented in the instrumental temperature record which extends back to the mid 19th century , and in paleoclimate proxy records over thousands of years . In 2013 , the Intergovernmental Panel on Climate Change ( IPCC ) Fifth Assessment Report concluded that `` It is extremely likely that human influence has been the dominant cause of the observed warming since the mid-20th century . '' The largest human influence has been emission of greenhouse gases such as carbon dioxide , methane and nitrous oxide . Climate model projections summarized in the report indicated that during the 21st century the global surface temperature is likely to rise a further 0.3 to for their lowest emissions scenario and 2.6 to for the highest emissions scenario . These findings have been recognized by the national science academies of the major industrialized nations and are not disputed by any scientific body of national or international standing . Future climate change and associated impacts will differ from region to region around the globe . Anticipated effects include warming global temperature , rising sea levels , changing precipitation , and expansion of deserts in the subtropics . Warming is expected to be greater over land than over the oceans and greatest in the Arctic , with the continuing retreat of glaciers , permafrost and sea ice . Other likely changes include more frequent extreme weather events including heat waves , droughts , heavy rainfall with floods and heavy snowfall ; ocean acidification ; and species extinctions due to shifting temperature regimes . Effects significant to humans include the threat to food security from decreasing crop yields and the abandonment of populated areas due to rising sea levels . Because the climate system has a large `` inertia '' and greenhouse gases will stay in the atmosphere for a long time , many of these effects will not only exist for decades or centuries , but will persist for tens of thousands of years . Possible societal responses to global warming include mitigation by emissions reduction , adaptation to its effects , building systems resilient to its effects , and possible future climate engineering . Most countries are parties to the United Nations Framework Convention on Climate Change ( UNFCCC ) , whose ultimate objective is to prevent dangerous anthropogenic climate change . Parties to the UNFCCC have agreed that deep cuts in emissions are required and that global warming should be limited to well below 2.0 C-change relative to pre-industrial levels , with efforts made to limit warming to 1.5 C-change . Public reactions to global warming and concern about its effects are also increasing . A global 2015 Pew Research Center report showed a median of 54 % consider it `` a very serious problem '' . There are significant regional differences , with Americans and Chinese ( whose economies are responsible for the greatest annual CO2 emissions ) among the least concerned . |
668 | Tide_gauge | Using satellite data rather than tide-gauge data that is normally used to measure sea levels allows for more precise estimates of global sea level, since it provides measurements of the open ocean. | Tide gauge A tide gauge ( also known as mareograph or marigraph , as well as sea-level recorder ) is a device for measuring the change in sea level relative to a datum . Sensors continuously record the height of the water level with respect to a height reference surface close to the geoid . Water enters the device by the bottom pipe ( far end of the tube , see picture ) , and electronic sensors measure its height and send the data to a tiny computer . Historical data are available for about 1,450 stations worldwide , of which about 950 provided updates to the global data center since January 2010 . At some places records cover centuries , for example in Amsterdam where data dating back to 1700 is available . When it comes to estimating the greater ocean picture , new modern tide gauges can often be improved upon by using satellite data . Tide gauges are used to measure tides and quantify the size of tsunamis . The measurements make it possible to derive the mean sea level . Using this method , sea level slopes up to several 0.1 m/1000 km and more have been detected . A tsunami can be detected when the sea level begins to rise , although warnings from seismic activity can be more useful . |
449 | Global_warming | So it's clear now we're not seeing dangerous global warming, and the climate models are wrong. | Global warming Global warming , also referred to as climate change , is the observed century-scale rise in the average temperature of the Earth 's climate system and its related effects . Multiple lines of scientific evidence show that the climate system is warming . Many of the observed changes since the 1950s are unprecedented in the instrumental temperature record which extends back to the mid 19th century , and in paleoclimate proxy records over thousands of years . In 2013 , the Intergovernmental Panel on Climate Change ( IPCC ) Fifth Assessment Report concluded that `` It is extremely likely that human influence has been the dominant cause of the observed warming since the mid-20th century . '' The largest human influence has been emission of greenhouse gases such as carbon dioxide , methane and nitrous oxide . Climate model projections summarized in the report indicated that during the 21st century the global surface temperature is likely to rise a further 0.3 to for their lowest emissions scenario and 2.6 to for the highest emissions scenario . These findings have been recognized by the national science academies of the major industrialized nations and are not disputed by any scientific body of national or international standing . Future climate change and associated impacts will differ from region to region around the globe . Anticipated effects include warming global temperature , rising sea levels , changing precipitation , and expansion of deserts in the subtropics . Warming is expected to be greater over land than over the oceans and greatest in the Arctic , with the continuing retreat of glaciers , permafrost and sea ice . Other likely changes include more frequent extreme weather events including heat waves , droughts , heavy rainfall with floods and heavy snowfall ; ocean acidification ; and species extinctions due to shifting temperature regimes . Effects significant to humans include the threat to food security from decreasing crop yields and the abandonment of populated areas due to rising sea levels . Because the climate system has a large `` inertia '' and greenhouse gases will stay in the atmosphere for a long time , many of these effects will not only exist for decades or centuries , but will persist for tens of thousands of years . Possible societal responses to global warming include mitigation by emissions reduction , adaptation to its effects , building systems resilient to its effects , and possible future climate engineering . Most countries are parties to the United Nations Framework Convention on Climate Change ( UNFCCC ) , whose ultimate objective is to prevent dangerous anthropogenic climate change . Parties to the UNFCCC have agreed that deep cuts in emissions are required and that global warming should be limited to well below 2.0 C-change relative to pre-industrial levels , with efforts made to limit warming to 1.5 C-change . Public reactions to global warming and concern about its effects are also increasing . A global 2015 Pew Research Center report showed a median of 54 % consider it `` a very serious problem '' . There are significant regional differences , with Americans and Chinese ( whose economies are responsible for the greatest annual CO2 emissions ) among the least concerned . |
2501 | Scientific_consensus_on_climate_change | The human fingerprint in global warming is evident in multiple lines of empirical evidence - in satellite measurements of outgoing infrared radiation, in surface measurements of downward infrared radiation, in the cooling stratosphere and other metrics. | Scientific consensus on climate change There is currently a strong scientific consensus that the Earth is warming and that this warming is mainly caused by human activities. This consensus is supported by various studies of scientists' opinions and by position statements of scientific organizations, many of which explicitly agree with the Intergovernmental Panel on Climate Change (IPCC) synthesis reports. Nearly all actively publishing climate scientists (97–98%) support the consensus on anthropogenic climate change, and the remaining 2% of contrarian studies either cannot be replicated or contain errors. |
196 | Earth | Without carbon dioxide, all life on Earth would die | Earth Earth ( from Eorðe -LSB- Γαῖα , Gaia -RSB- Terra ) , otherwise known as the World or the Globe , is the third planet from the Sun and the only object in the Universe known to harbor life . It is the densest planet in the Solar System and the largest of the four terrestrial planets . According to radiometric dating and other sources of evidence , Earth formed about 4.54 billion years ago . Earth 's gravity interacts with other objects in space , especially the Sun and the Moon , Earth 's only natural satellite . During one orbit around the Sun , Earth rotates about its axis over 365 times ; thus , an Earth year is about 365.26 days long . Earth 's axis of rotation is tilted , producing seasonal variations on the planet 's surface . The gravitational interaction between the Earth and Moon causes ocean tides , stabilizes the Earth 's orientation on its axis , and gradually slows its rotation . Earth 's lithosphere is divided into several rigid tectonic plates that migrate across the surface over periods of many millions of years . About 71 % of Earth 's surface is covered with water , mostly by its oceans . The remaining 29 % is land consisting of continents and islands that together have many lakes , rivers and other sources of water that contribute to the hydrosphere . The majority of Earth 's polar regions are covered in ice , including the Antarctic ice sheet and the sea ice of the Arctic ice pack . Earth 's interior remains active with a solid iron inner core , a liquid outer core that generates the Earth 's magnetic field , and a convecting mantle that drives plate tectonics . Within the first billion years of Earth 's history , life appeared in the oceans and began to affect the Earth 's atmosphere and surface , leading to the proliferation of aerobic and anaerobic organisms . Some geological evidence indicates that life may have arisen as much as 4.1 billion years ago . Since then , the combination of Earth 's distance from the Sun , physical properties , and geological history have allowed life to evolve and thrive . In the history of the Earth , biodiversity has gone through long periods of expansion , occasionally punctuated by mass extinction events . Over 99 % of all species that ever lived on Earth are extinct . Estimates of the number of species on Earth today vary widely ; most species have not been described . Over 7.4 billion humans live on Earth and depend on its biosphere and minerals for their survival . Humans have developed diverse societies and cultures ; politically , the world has about 200 sovereign states . |
1700 | Global_warming | Methane plays a minor role in global warming but could get much worse if permafrost starts to melt. | Global warming Global warming , also referred to as climate change , is the observed century-scale rise in the average temperature of the Earth 's climate system and its related effects . Multiple lines of scientific evidence show that the climate system is warming . Many of the observed changes since the 1950s are unprecedented in the instrumental temperature record which extends back to the mid 19th century , and in paleoclimate proxy records over thousands of years . In 2013 , the Intergovernmental Panel on Climate Change ( IPCC ) Fifth Assessment Report concluded that `` It is extremely likely that human influence has been the dominant cause of the observed warming since the mid-20th century . '' The largest human influence has been emission of greenhouse gases such as carbon dioxide , methane and nitrous oxide . Climate model projections summarized in the report indicated that during the 21st century the global surface temperature is likely to rise a further 0.3 to for their lowest emissions scenario and 2.6 to for the highest emissions scenario . These findings have been recognized by the national science academies of the major industrialized nations and are not disputed by any scientific body of national or international standing . Future climate change and associated impacts will differ from region to region around the globe . Anticipated effects include warming global temperature , rising sea levels , changing precipitation , and expansion of deserts in the subtropics . Warming is expected to be greater over land than over the oceans and greatest in the Arctic , with the continuing retreat of glaciers , permafrost and sea ice . Other likely changes include more frequent extreme weather events including heat waves , droughts , heavy rainfall with floods and heavy snowfall ; ocean acidification ; and species extinctions due to shifting temperature regimes . Effects significant to humans include the threat to food security from decreasing crop yields and the abandonment of populated areas due to rising sea levels . Because the climate system has a large `` inertia '' and greenhouse gases will stay in the atmosphere for a long time , many of these effects will not only exist for decades or centuries , but will persist for tens of thousands of years . Possible societal responses to global warming include mitigation by emissions reduction , adaptation to its effects , building systems resilient to its effects , and possible future climate engineering . Most countries are parties to the United Nations Framework Convention on Climate Change ( UNFCCC ) , whose ultimate objective is to prevent dangerous anthropogenic climate change . Parties to the UNFCCC have agreed that deep cuts in emissions are required and that global warming should be limited to well below 2.0 C-change relative to pre-industrial levels , with efforts made to limit warming to 1.5 C-change . Public reactions to global warming and concern about its effects are also increasing . A global 2015 Pew Research Center report showed a median of 54 % consider it `` a very serious problem '' . There are significant regional differences , with Americans and Chinese ( whose economies are responsible for the greatest annual CO2 emissions ) among the least concerned . |
2978 | Atmosphere_of_Venus | The lower temperatures at this "coldest point" have caused global water vapor levels to drop, even as carbon levels rise. | Atmosphere of Venus The atmosphere of Venus is the layer of gases surrounding Venus . It is composed primarily of carbon dioxide and is much denser and hotter than that of Earth . The temperature at the surface is 740 K ( 467 ° C , 872 ° F ) , and the pressure is 93 bar ( 9.3 MPa ) , roughly the pressure found 900 m underwater on Earth . The Venusian atmosphere supports opaque clouds made of sulfuric acid , making optical Earth-based and orbital observation of the surface impossible . Information about the topography has been obtained exclusively by radar imaging . Aside from carbon dioxide , the other main component is nitrogen . Other chemical compounds are present only in trace amounts . Mikhail Lomonosov was the first person to hypothesize the existence of an atmosphere on Venus based on his observation of the transit of Venus of 1761 in a small observatory near his house in Saint Petersburg , Russia . Aside from the very surface layers , the atmosphere is in a state of vigorous circulation . The upper layer of troposphere exhibits a phenomenon of super-rotation , in which the atmosphere circles the planet in just four Earth days , much faster than the planet 's sidereal day of 243 days . The winds supporting super-rotation blow at a speed of 100 m/s ( ~ 360 km/h or 220 mph ) or more . Winds move at up to 60 times the speed of the planet 's rotation , while Earth 's fastest winds are only 10 % to 20 % rotation speed . On the other hand , the wind speed becomes increasingly slower as the elevation from the surface decreases , with the breeze barely reaching the speed of 10 km/h ( 2.8 m/s ) on the surface . Near the poles are anticyclonic structures called polar vortices . Each vortex is double-eyed and shows a characteristic S-shaped pattern of clouds . Above there is an intermediate layer of mesosphere which separates the troposphere from the thermosphere . The thermosphere is also characterized by strong circulation , but very different in its nature - the gases heated and partially ionized by sunlight in the sunlit hemisphere migrate to the dark hemisphere where they recombine and downwell . Unlike Earth , Venus lacks a magnetic field . Its ionosphere separates the atmosphere from outer space and the solar wind . This ionised layer excludes the solar magnetic field , giving Venus a distinct magnetic environment . This is considered Venus 's induced magnetosphere . Lighter gases , including water vapour , are continuously blown away by the solar wind through the induced magnetotail . It is speculated that the atmosphere of Venus up to around 4 billion years ago was more like that of the Earth with liquid water on the surface . A runaway greenhouse effect may have been caused by the evaporation of the surface water and subsequent rise of the levels of other greenhouse gases . Despite the harsh conditions on the surface , the atmospheric pressure and temperature at about 50 km to 65 km above the surface of the planet is nearly the same as that of the Earth , making its upper atmosphere the most Earth-like area in the Solar System , even more so than the surface of Mars . Due to the similarity in pressure and temperature and the fact that breathable air ( 21 % oxygen , 78 % nitrogen ) is a lifting gas on Venus in the same way that helium is a lifting gas on Earth , the upper atmosphere has been proposed as a location for both exploration and colonization . On January 29 , 2013 , ESA scientists reported that the ionosphere of the planet Venus streams outwards in a manner similar to `` the ion tail seen streaming from a comet under similar conditions . '' |
2521 | Earth | The atmosphere of the Earth is less able to absorb shortwave radiation from the Sun than thermal radiation coming from the surface. | Earth Earth ( from Eorðe -LSB- Γαῖα , Gaia -RSB- Terra ) , otherwise known as the World or the Globe , is the third planet from the Sun and the only object in the Universe known to harbor life . It is the densest planet in the Solar System and the largest of the four terrestrial planets . According to radiometric dating and other sources of evidence , Earth formed about 4.54 billion years ago . Earth 's gravity interacts with other objects in space , especially the Sun and the Moon , Earth 's only natural satellite . During one orbit around the Sun , Earth rotates about its axis over 365 times ; thus , an Earth year is about 365.26 days long . Earth 's axis of rotation is tilted , producing seasonal variations on the planet 's surface . The gravitational interaction between the Earth and Moon causes ocean tides , stabilizes the Earth 's orientation on its axis , and gradually slows its rotation . Earth 's lithosphere is divided into several rigid tectonic plates that migrate across the surface over periods of many millions of years . About 71 % of Earth 's surface is covered with water , mostly by its oceans . The remaining 29 % is land consisting of continents and islands that together have many lakes , rivers and other sources of water that contribute to the hydrosphere . The majority of Earth 's polar regions are covered in ice , including the Antarctic ice sheet and the sea ice of the Arctic ice pack . Earth 's interior remains active with a solid iron inner core , a liquid outer core that generates the Earth 's magnetic field , and a convecting mantle that drives plate tectonics . Within the first billion years of Earth 's history , life appeared in the oceans and began to affect the Earth 's atmosphere and surface , leading to the proliferation of aerobic and anaerobic organisms . Some geological evidence indicates that life may have arisen as much as 4.1 billion years ago . Since then , the combination of Earth 's distance from the Sun , physical properties , and geological history have allowed life to evolve and thrive . In the history of the Earth , biodiversity has gone through long periods of expansion , occasionally punctuated by mass extinction events . Over 99 % of all species that ever lived on Earth are extinct . Estimates of the number of species on Earth today vary widely ; most species have not been described . Over 7.4 billion humans live on Earth and depend on its biosphere and minerals for their survival . Humans have developed diverse societies and cultures ; politically , the world has about 200 sovereign states . |
1821 | Stephen_Harper | The Conservatives' recent budget made no mention of climate change. | Stephen Harper Stephen Joseph Harper ( born April 30 , 1959 ) is a Canadian entrepreneur and retired politician who served as the 22nd Prime Minister of Canada , from February 6 , 2006 to November 4 , 2015 . He was the first prime minister to come from the modern Conservative Party of Canada , which was formed by a merger of the Progressive Conservative Party and the Canadian Alliance . Harper was member of parliament for the riding of Calgary Heritage in Alberta from 2002 to 2016 ( previously known as Calgary Southwest from 2002 to 2015 ) . Earlier , from 1993 to 1997 , he was the MP for Calgary West , representing the Reform Party of Canada . He was one of the founding members of the Reform Party , but did not seek re-election in the 1997 federal election . Harper instead joined and later led the National Citizens Coalition , a conservative lobbyist group . In 2002 , he succeeded Stockwell Day as leader of the Canadian Alliance , the successor to the Reform Party and returned to parliament as Leader of the Opposition . In 2003 , he reached an agreement with Progressive Conservative leader Peter MacKay for the merger of their two parties to form the Conservative Party of Canada . He was elected as the party 's first leader , in March 2004 . Harper stepped down as MP on August 26 , 2016 . The 2006 federal election resulted in a minority government led by the Conservative Party with Harper becoming the 22nd Prime Minister of Canada . By proportion of seats , this was Canada 's smallest minority government since Confederation . Despite this , it was the longest-serving minority government overall . In the 2008 federal election , the Conservative Party won a stronger minority , showing a small increase in the percentage of the popular vote and increased representation in the Canadian House of Commons , with 143 of 308 seats . The 40th Canadian Parliament was dissolved in March , 2011 , after a no-confidence vote that deemed the Cabinet to be in contempt of parliament . In the federal election that followed , the Conservatives won a majority government , the first since the 2000 federal election ; the party won 166 seats , an increase of 23 seats from the October 2008 election . Though Harper won his seat of Calgary-Heritage in the October 19 , 2015 , federal election , the Conservative Party was defeated by the Liberal Party of Canada , led by Justin Trudeau , who was sworn-in as Harper 's successor on November 4 , 2015 . Harper resigned as party leader on October 19 , 2015 , and the Conservative Party caucus chose an interim leader , Rona Ambrose , on November 5 , 2015 , to serve until a leadership election . Harper moved back to Calgary , Alberta , and commuted to Ottawa as an opposition backbench member of parliament . |
2743 | Richard_Lindzen | "a [cloudcover] change in the Tropics could lead to a negative feedback in the global climate, with a feedback factor of about –1.1, which if correct, would more than cancel all the positive feedbacks in the more sensitive current climate models" (Lindzen et al. | Richard Lindzen Richard Siegmund Lindzen ( born February 8 , 1940 ) is an American atmospheric physicist known for his work in the dynamics of the middle atmosphere , atmospheric tides , and ozone photochemistry . He has published more than 200 scientific papers and books . From 1983 until his retirement in 2013 , he was Alfred P. Sloan Professor of Meteorology at the Massachusetts Institute of Technology . He was a lead author of Chapter 7 , `` Physical Climate Processes and Feedbacks , '' of the Intergovernmental Panel on Climate Change 's Third Assessment Report on climate change . He has criticized the scientific consensus about climate change and what he has called `` climate alarmism . '' |
512 | Greenhouse_effect | water vapour has been the main greenhouse gas and carbon dioxide has had a minuscule effect on global climate | Greenhouse effect The greenhouse effect is the process by which radiation from a planet 's atmosphere warms the planet 's surface to a temperature above what it would be without its atmosphere . If a planet 's atmosphere contains radiatively active gases ( i.e. , greenhouse gases ) the atmosphere will radiate energy in all directions . Part of this radiation is directed towards the surface , warming it . The downward component of this radiation -- that is , the strength of the greenhouse effect -- will depend on the atmosphere 's temperature and on the amount of greenhouse gases that the atmosphere contains . On Earth , the atmosphere is warmed by absorption of infrared thermal radiation from the underlying surface ( heated by the sun ) , absorption of shorter wavelength radiant energy from the sun , and convective heat fluxes from the surface . Greenhouse gases in the atmosphere radiate energy , some of which is directed to the surface and lower atmosphere . The mechanism that produces this difference between the actual surface temperature and the effective temperature is due to the atmosphere and is known as the greenhouse effect . Earth 's natural greenhouse effect is critical to supporting life . Human activities , primarily the burning of fossil fuels and clearing of forests , have intensified the natural greenhouse effect , causing global warming . The mechanism is named after a faulty analogy with the effect of solar radiation passing through glass and warming a greenhouse . The way a greenhouse retains heat is fundamentally different , as a greenhouse works by reducing airflow and retaining warm air inside the structure . |
2381 | Stern_Review | Economic assessments of proposed policy to put a price on carbon emissions are in widespread agreement that the net economic impact will be minor. | Stern Review The Stern Review on the Economics of Climate Change is a 700-page report released for the Government of the United Kingdom on 30 October 2006 by economist Nicholas Stern , chair of the Grantham Research Institute on Climate Change and the Environment at the London School of Economics ( LSE ) and also chair of the Centre for Climate Change Economics and Policy ( CCCEP ) at Leeds University and LSE . The report discusses the effect of global warming on the world economy . Although not the first economic report on climate change , it is significant as the largest and most widely known and discussed report of its kind . The Review states that climate change is the greatest and widest-ranging market failure ever seen , presenting a unique challenge for economics . The Review provides prescriptions including environmental taxes to minimise the economic and social disruptions . The Stern Review 's main conclusion is that the benefits of strong , early action on climate change far outweigh the costs of not acting . The Review points to the potential impacts of climate change on water resources , food production , health , and the environment . According to the Review , without action , the overall costs of climate change will be equivalent to losing at least 5 % of global gross domestic product ( GDP ) each year , now and forever . Including a wider range of risks and impacts could increase this to 20 % of GDP or more , also indefinitely . Stern believes that 5 -- 6 degrees of temperature increase is `` a real possibility . '' The Review proposes that one percent of global GDP per annum is required to be invested to avoid the worst effects of climate change . In June 2008 , Stern increased the estimate for the annual cost of achieving stabilisation between 500 and 550 ppm CO2e to 2 % of GDP to account for faster than expected climate change . There has been a mixed reaction to the Stern Review from economists . Several economists have been critical of the Review , for example , a paper by Byatt et al. ( 2006 ) describes the Review as `` deeply flawed '' . Some economists ( such as Brad DeLong and John Quiggin ) have supported the Review . Others have criticised aspects of Review 's analysis , but argued that some of its conclusions might still be justified based on other grounds , e.g. , see papers by Martin Weitzman ( 2007 ) and Dieter Helm ( 2008 ) . |
2707 | Arctic | The full data for latitudes 64-90°N reveal the Arctic is warmer today than in 1940. | Arctic The Arctic ( -LSB- ˈɑrktɪk -RSB- or -LSB- ˈɑrtɪk -RSB- ) is a polar region located at the northernmost part of Earth . The Arctic consists of the Arctic Ocean , adjacent seas , and parts of Alaska ( United States ) , Canada , Finland , Greenland ( Denmark ) , Iceland , Norway , Russia and Sweden . Land within the Arctic region has seasonally varying snow and ice cover , with predominantly treeless permafrost-containing tundra . Arctic seas contain seasonal sea ice in many places . The Arctic region is a unique area among Earth 's ecosystems . For example , the cultures in the region and the Arctic indigenous peoples have adapted to its cold and extreme conditions . In recent years , Arctic sea ice decline has been caused by global warming . Life in the Arctic includes organisms living in the ice , zooplankton and phytoplankton , fish and marine mammals , birds , land animals , plants and human societies . Arctic land is bordered by the subarctic . |
3011 | Little_Ice_Age | A South African paper has found a 21 year cycle synchronous with the solar cycle (Alexander 2007). | Little Ice Age The Little Ice Age ( LIA ) was a period of cooling that occurred after the Medieval Warm Period . Although it was not a true ice age , the term was introduced into scientific literature by François E. Matthes in 1939 . It has been conventionally defined as a period extending from the 16th to the 19th centuries , but some experts prefer an alternative timespan from about 1300 to about 1850 . Climatologists and historians working with local records no longer expect to agree on either the start or end dates of the period , which varied according to local conditions . The NASA Earth Observatory notes three particularly cold intervals : one beginning about 1650 , another about 1770 , and the last in 1850 , all separated by intervals of slight warming . The Intergovernmental Panel on Climate Change Third Assessment Report considered the timing and areas affected by the Little Ice Age suggested largely-independent regional climate changes rather than a globally-synchronous increased glaciation . At most , there was modest cooling of the Northern Hemisphere during the period . Several causes have been proposed : cyclical lows in solar radiation , heightened volcanic activity , changes in the ocean circulation , variations in Earth 's orbit and axial tilt ( orbital forcing ) , inherent variability in global climate , and decreases in the human population . |
298 | Scientific_consensus_on_climate_change | Only very few peer-reviewed papers even go so far as to say that recent warming is chiefly anthropogenic. | Scientific consensus on climate change There is currently a strong scientific consensus that the Earth is warming and that this warming is mainly caused by human activities. This consensus is supported by various studies of scientists' opinions and by position statements of scientific organizations, many of which explicitly agree with the Intergovernmental Panel on Climate Change (IPCC) synthesis reports. Nearly all actively publishing climate scientists (97–98%) support the consensus on anthropogenic climate change, and the remaining 2% of contrarian studies either cannot be replicated or contain errors. |
1435 | Marine_pollution | An area of coastal ecosystems larger than New York City is destroyed every year, removing an important buffer from extreme weather for coastal communities and releasing carbon dioxide into the atmosphere. | Marine pollution Marine pollution occurs when harmful , or potentially harmful , effects result from the entry into the ocean of chemicals , particles , industrial , agricultural and residential waste , noise , or the spread of invasive organisms . Eighty percent of marine pollution comes from land . Air pollution is also a contributing factor by carrying off pesticides or dirt into the ocean . Land and air pollution have proven to be harmful to marine life and its habitats . The pollution often comes from non point sources such as agricultural runoff , wind-blown debris and dust . Nutrient pollution , a form of water pollution , refers to contamination by excessive inputs of nutrients . It is a primary cause of eutrophication of surface waters , in which excess nutrients , usually nitrogen or phosphorus , stimulate algae growth . Many potentially toxic chemicals adhere to tiny particles which are then taken up by plankton and benthos animals , most of which are either deposit or filter feeders . In this way , the toxins are concentrated upward within ocean food chains . Many particles combine chemically in a manner highly depletive of oxygen , causing estuaries to become anoxic . When pesticides are incorporated into the marine ecosystem , they quickly become absorbed into marine food webs . Once in the food webs , these pesticides can cause mutations , as well as diseases , which can be harmful to humans as well as the entire food web . Toxic metals can also be introduced into marine food webs . These can cause a change to tissue matter , biochemistry , behaviour , reproduction , and suppress growth in marine life . Also , many animal feeds have a high fish meal or fish hydrolysate content . In this way , marine toxins can be transferred to land animals , and appear later in meat and dairy products . |
534 | Global_warming | Domino-effect of climate events could move Earth into a 'hothouse' state | Global warming Global warming , also referred to as climate change , is the observed century-scale rise in the average temperature of the Earth 's climate system and its related effects . Multiple lines of scientific evidence show that the climate system is warming . Many of the observed changes since the 1950s are unprecedented in the instrumental temperature record which extends back to the mid 19th century , and in paleoclimate proxy records over thousands of years . In 2013 , the Intergovernmental Panel on Climate Change ( IPCC ) Fifth Assessment Report concluded that `` It is extremely likely that human influence has been the dominant cause of the observed warming since the mid-20th century . '' The largest human influence has been emission of greenhouse gases such as carbon dioxide , methane and nitrous oxide . Climate model projections summarized in the report indicated that during the 21st century the global surface temperature is likely to rise a further 0.3 to for their lowest emissions scenario and 2.6 to for the highest emissions scenario . These findings have been recognized by the national science academies of the major industrialized nations and are not disputed by any scientific body of national or international standing . Future climate change and associated impacts will differ from region to region around the globe . Anticipated effects include warming global temperature , rising sea levels , changing precipitation , and expansion of deserts in the subtropics . Warming is expected to be greater over land than over the oceans and greatest in the Arctic , with the continuing retreat of glaciers , permafrost and sea ice . Other likely changes include more frequent extreme weather events including heat waves , droughts , heavy rainfall with floods and heavy snowfall ; ocean acidification ; and species extinctions due to shifting temperature regimes . Effects significant to humans include the threat to food security from decreasing crop yields and the abandonment of populated areas due to rising sea levels . Because the climate system has a large `` inertia '' and greenhouse gases will stay in the atmosphere for a long time , many of these effects will not only exist for decades or centuries , but will persist for tens of thousands of years . Possible societal responses to global warming include mitigation by emissions reduction , adaptation to its effects , building systems resilient to its effects , and possible future climate engineering . Most countries are parties to the United Nations Framework Convention on Climate Change ( UNFCCC ) , whose ultimate objective is to prevent dangerous anthropogenic climate change . Parties to the UNFCCC have agreed that deep cuts in emissions are required and that global warming should be limited to well below 2.0 C-change relative to pre-industrial levels , with efforts made to limit warming to 1.5 C-change . Public reactions to global warming and concern about its effects are also increasing . A global 2015 Pew Research Center report showed a median of 54 % consider it `` a very serious problem '' . There are significant regional differences , with Americans and Chinese ( whose economies are responsible for the greatest annual CO2 emissions ) among the least concerned . |
2011 | Paris_Agreement | U.S. Pays $1 Billion into Green Climate Fund, Top Polluters Pay Nothing | Paris Agreement The Paris Agreement ( Accord de Paris ) is an agreement within the United Nations Framework Convention on Climate Change ( UNFCCC ) dealing with greenhouse gas emissions mitigation , adaptation and finance starting in the year 2020 . The language of the agreement was negotiated by representatives of 195 countries at the 21st Conference of the Parties of the UNFCCC in Paris and adopted by consensus on 12 December 2015 . It was opened for signature on 22 April 2016 ( Earth Day ) at a ceremony in New York . As of May 2017 , 195 UNFCCC members have signed the treaty , 147 of which have ratified it . After several European Union states ratified the agreement in October 2016 , there were enough countries that had ratified the agreement that produce enough of the world 's greenhouse gases for the agreement to enter into force . The agreement went into effect on 4 November 2016 . The head of the Paris Conference , France 's foreign minister Laurent Fabius , said this `` ambitious and balanced '' plan is a `` historic turning point '' in the goal of reducing global warming . One year on , the ratification of the Paris Agreement was celebrated by the Mayor of Paris Anne Hidalgo by illuminating the Eiffel Tower and the Arc de Triomphe , Paris ' most iconic monuments , in green . |
2054 | Carbon_dioxide | During the period 1940 to 1976 there was a cooling of the climate despite increasing CO2 levels. | Carbon dioxide Carbon dioxide ( chemical formula ) is a colorless gas with a density about 60 % higher than that of air ( 1.225 g/L ) that is odorless at normally encountered concentrations . Carbon dioxide consists of a carbon atom covalently double bonded to two oxygen atoms . It occurs naturally in Earth 's atmosphere as a trace gas at a concentration of about 0.04 percent ( 400 ppm ) by volume . Natural sources include volcanoes , hot springs and geysers , and it is freed from carbonate rocks by dissolution in water and acids . Because carbon dioxide is soluble in water , it occurs naturally in groundwater , rivers and lakes , ice caps , glaciers and seawater . It is present in deposits of petroleum and natural gas . As the source of available carbon in the carbon cycle , atmospheric carbon dioxide is the primary carbon source for life on Earth and its concentration in Earth 's pre-industrial atmosphere since late in the Precambrian has been regulated by photosynthetic organisms and geological phenomena . Plants , algae and cyanobacteria use light energy to photosynthesize carbohydrate from carbon dioxide and water , with oxygen produced as a waste product . Carbon dioxide is produced by all aerobic organisms when they metabolize carbohydrates and lipids to produce energy by respiration . It is returned to water via the gills of fish and to the air via the lungs of air-breathing land animals , including humans . Carbon dioxide is produced during the processes of decay of organic materials and the fermentation of sugars in bread , beer and winemaking . It is produced by combustion of wood and other organic materials and fossil fuels such as coal , peat , petroleum and natural gas . It is a versatile industrial material , used , for example , as an inert gas in welding and fire extinguishers , as a pressurizing gas in air guns and oil recovery , as a chemical feedstock and in liquid form as a solvent in decaffeination of coffee and supercritical drying . It is added to drinking water and carbonated beverages including beer and sparkling wine to add effervescence . The frozen solid form of , known as `` dry ice '' is used as a refrigerant and as an abrasive in dry-ice blasting . Carbon dioxide is the most significant long-lived greenhouse gas in Earth 's atmosphere . Since the Industrial Revolution anthropogenic emissions - primarily from use of fossil fuels and deforestation - have rapidly increased its concentration in the atmosphere , leading to global warming . Carbon dioxide also causes ocean acidification because it dissolves in water to form carbonic acid . |
365 | Influenza_A_virus | The knock-on consequences affect national security, as the scale of the challenges involved, such as pandemic disease outbreaks, are overwhelming. | Influenza A virus Influenza A virus causes influenza in birds and some mammals , and is the only species of influenza virus A. Influenza virus A is a genus of the Orthomyxoviridae family of viruses . Strains of all subtypes of influenza A virus have been isolated from wild birds , although disease is uncommon . Some isolates of influenza A virus cause severe disease both in domestic poultry and , rarely , in humans . Occasionally , viruses are transmitted from wild aquatic birds to domestic poultry , and this may cause an outbreak or give rise to human influenza pandemics . Influenza A viruses are negative-sense , single-stranded , segmented RNA viruses . The several subtypes are labeled according to an H number ( for the type of hemagglutinin ) and an N number ( for the type of neuraminidase ) . There are 18 different known H antigens ( H1 to H18 ) and 11 different known N antigens ( N1 to N11 ) . H17 was isolated from fruit bats in 2012 . H18N11 was discovered in a Peruvian bat in 2013 . Each virus subtype has mutated into a variety of strains with differing pathogenic profiles ; some are pathogenic to one species but not others , some are pathogenic to multiple species . A filtered and purified influenza A vaccine for humans has been developed , and many countries have stockpiled it to allow a quick administration to the population in the event of an avian influenza pandemic . Avian influenza is sometimes called avian flu , and colloquially , bird flu . In 2011 , researchers reported the discovery of an antibody effective against all types of the influenza A virus . |
1160 | Environmental_degradation | With more CO2 in the atmosphere, the challenge [feeding 2.5 billion more people] can and will be met. | Environmental degradation Environmental degradation is the deterioration of the environment through depletion of resources such as air , water and soil ; the destruction of ecosystems ; habitat destruction ; the extinction of wildlife ; and pollution . It is defined as any change or disturbance to the environment perceived to be deleterious or undesirable . As indicated by the I = PAT equation , environmental impact ( I ) or degradation is caused by the combination of an already very large and increasing human population ( P ) , continually increasing economic growth or per capita affluence ( A ) , and the application of resource depleting and polluting technology ( T ) . Environmental degradation is one of the ten threats officially cautioned by the High-level Panel on Threats , Challenges and Change of the United Nations . The United Nations International Strategy for Disaster Reduction defines environmental degradation as `` The reduction of the capacity of the environment to meet social and ecological objectives , and needs '' . Environmental degradation is of many types . When natural habitats are destroyed or natural resources are depleted , the environment is degraded . Efforts to counteract this problem include environmental protection and environmental resources management . |
948 | University_of_Massachusetts_Amherst | In a study last year, Robert M. DeConto of the University of Massachusetts, Amherst, and David Pollard of Pennsylvania State University used their computer model to predict what would happen if emissions were reduced sharply over the next few decades, in line with international climate goals. | University of Massachusetts Amherst The University of Massachusetts Amherst ( abbreviated UMass Amherst and colloquially referred to as UMass or Massachusetts ) is a public research and land-grant university in Amherst , Massachusetts , United States , and the flagship of the University of Massachusetts system . With approximately 1,300 faculty members and more than 29,000 students , UMass Amherst is the largest public university in New England and is ranked as tied for the 27th best public university in the nation . The university offers bachelor 's degrees , master 's degrees , and doctoral degrees in 111 undergraduate , 75 master 's and 47 doctoral programs in nine schools and colleges . The main campus is situated north of downtown Amherst . In a 2009 article for MSN.com , Amherst was ranked first in Best College Towns in the United States . In 2012 , U.S. News and World Report ranked Amherst among the Top 10 Great College Towns in America . It is also a member of the Five College Consortium . The University of Massachusetts Amherst is categorized as a Research University with Highest research activity by the Carnegie Foundation for the Advancement of Teaching . In fiscal year 2014 , UMass Amherst had research expenditures exceeding $ 200 million . UMass Amherst sports teams are called the Minutemen and Minutewomen , the colors being maroon , black , and white ; the school mascot is Sam the Minuteman . All teams participate in NCAA Division I . The university is a member of the Atlantic 10 Conference , while playing ice hockey in Hockey East and football as an FBS Independent . |
960 | Global_warming | This means the global temperature trend has now shown no further warming for 19 years | Global warming Global warming , also referred to as climate change , is the observed century-scale rise in the average temperature of the Earth 's climate system and its related effects . Multiple lines of scientific evidence show that the climate system is warming . Many of the observed changes since the 1950s are unprecedented in the instrumental temperature record which extends back to the mid 19th century , and in paleoclimate proxy records over thousands of years . In 2013 , the Intergovernmental Panel on Climate Change ( IPCC ) Fifth Assessment Report concluded that `` It is extremely likely that human influence has been the dominant cause of the observed warming since the mid-20th century . '' The largest human influence has been emission of greenhouse gases such as carbon dioxide , methane and nitrous oxide . Climate model projections summarized in the report indicated that during the 21st century the global surface temperature is likely to rise a further 0.3 to for their lowest emissions scenario and 2.6 to for the highest emissions scenario . These findings have been recognized by the national science academies of the major industrialized nations and are not disputed by any scientific body of national or international standing . Future climate change and associated impacts will differ from region to region around the globe . Anticipated effects include warming global temperature , rising sea levels , changing precipitation , and expansion of deserts in the subtropics . Warming is expected to be greater over land than over the oceans and greatest in the Arctic , with the continuing retreat of glaciers , permafrost and sea ice . Other likely changes include more frequent extreme weather events including heat waves , droughts , heavy rainfall with floods and heavy snowfall ; ocean acidification ; and species extinctions due to shifting temperature regimes . Effects significant to humans include the threat to food security from decreasing crop yields and the abandonment of populated areas due to rising sea levels . Because the climate system has a large `` inertia '' and greenhouse gases will stay in the atmosphere for a long time , many of these effects will not only exist for decades or centuries , but will persist for tens of thousands of years . Possible societal responses to global warming include mitigation by emissions reduction , adaptation to its effects , building systems resilient to its effects , and possible future climate engineering . Most countries are parties to the United Nations Framework Convention on Climate Change ( UNFCCC ) , whose ultimate objective is to prevent dangerous anthropogenic climate change . Parties to the UNFCCC have agreed that deep cuts in emissions are required and that global warming should be limited to well below 2.0 C-change relative to pre-industrial levels , with efforts made to limit warming to 1.5 C-change . Public reactions to global warming and concern about its effects are also increasing . A global 2015 Pew Research Center report showed a median of 54 % consider it `` a very serious problem '' . There are significant regional differences , with Americans and Chinese ( whose economies are responsible for the greatest annual CO2 emissions ) among the least concerned . |
2916 | Air_pollution | If Senator Wong was really serious about her science she would stop breathing because you inhale air that's got 385 parts per million carbon dioxide in it | Air pollution Air pollution occurs when harmful substances including particulates and biological molecules are introduced into Earth 's atmosphere . It may cause diseases , allergies or death in humans ; it may also cause harm to other living organisms such as animals and food crops , and may damage the natural or built environment . Human activity and natural processes can both generate air pollution . Indoor air pollution and poor urban air quality are listed as two of the world 's worst toxic pollution problems in the 2008 Blacksmith Institute World 's Worst Polluted Places report . According to the 2014 WHO report , air pollution in 2012 caused the deaths of around 7 million people worldwide , an estimate roughly matched by the International Energy Agency . |
2485 | Scientific_consensus_on_climate_change | A natural cycle requires a forcing, and no known forcing exists that fits the fingerprints of observed warming - except anthropogenic greenhouse gases. | Scientific consensus on climate change There is currently a strong scientific consensus that the Earth is warming and that this warming is mainly caused by human activities. This consensus is supported by various studies of scientists' opinions and by position statements of scientific organizations, many of which explicitly agree with the Intergovernmental Panel on Climate Change (IPCC) synthesis reports. Nearly all actively publishing climate scientists (97–98%) support the consensus on anthropogenic climate change, and the remaining 2% of contrarian studies either cannot be replicated or contain errors. |
3056 | Cosmic_ray | "The observed data show that CFCs conspiring with cosmic rays most likely caused both the Antarctic ozone hole and global warming... | Cosmic ray Cosmic rays are high-energy radiation , mainly originating outside the Solar System . Upon impact with the Earth 's atmosphere , cosmic rays can produce showers of secondary particles that sometimes reach the surface . Composed primarily of high-energy protons and atomic nuclei , they are of mysterious origin . Data from the Fermi Space Telescope ( 2013 ) have been interpreted as evidence that a significant fraction of primary cosmic rays originate from the supernovae explosions of stars . Active galactic nuclei probably also produce cosmic rays . |
697 | Physics | While many scientists have acknowledged the mismatch between model predictions and actual temperature observations, few have really challenged the validity of the models themselves. | Physics Physics ( from -LSB- φυσική , phusikḗ ( epistḗmē ) , knowledge of nature -RSB- , from φύσις phúsis `` nature '' ) is the natural science that involves the study of matter and its motion and behavior through space and time , along with related concepts such as energy and force . One of the most fundamental scientific disciplines , the main goal of physics is to understand how the universe behaves . Physics is one of the oldest academic disciplines , perhaps the oldest through its inclusion of astronomy . Over the last two millennia , physics was a part of natural philosophy along with chemistry , biology , and certain branches of mathematics , but during the scientific revolution in the 17th century , the natural sciences emerged as unique research programs in their own right . Physics intersects with many interdisciplinary areas of research , such as biophysics and quantum chemistry , and the boundaries of physics are not rigidly defined . New ideas in physics often explain the fundamental mechanisms of other sciences while opening new avenues of research in areas such as mathematics and philosophy . Physics also makes significant contributions through advances in new technologies that arise from theoretical breakthroughs . For example , advances in the understanding of electromagnetism or nuclear physics led directly to the development of new products that have dramatically transformed modern-day society , such as television , computers , domestic appliances , and nuclear weapons ; advances in thermodynamics led to the development of industrialization , and advances in mechanics inspired the development of calculus . The United Nations named 2005 the World Year of Physics . |
185 | Carbon_dioxide_in_Earth's_atmosphere | Modellers assume carbon dioxide drives climate change | Carbon dioxide in Earth's atmosphere Carbon dioxide is an important trace gas in Earth 's atmosphere . Currently it constitutes about 0.041 % ( equal to 410 parts per million ; ppm ) by volume of the atmosphere . Despite its relatively small concentration is a potent greenhouse gas and plays a vital role in regulating Earth 's surface temperature through radiative forcing and the greenhouse effect . Reconstructions show that concentrations of in the atmosphere have varied , ranging from as high as 7,000 ppm during the Cambrian period about 500 million years ago to as low as 180 ppm during the Quaternary glaciation of the last two million years . Carbon dioxide is an integral part of the carbon cycle , a biogeochemical cycle in which carbon is exchanged between the Earth 's oceans , soil , rocks and the biosphere . Plants and other photoautotrophs use solar energy to produce carbohydrate from atmospheric carbon dioxide and water by photosynthesis . Almost all other organisms depend on carbohydrate derived from photosynthesis as their primary source of energy and carbon compounds . The current episode of global warming is attributed to increasing emissions of and other greenhouse gases into Earth 's atmosphere . The global annual mean concentration of in the atmosphere has increased by more than 40 % since the start of the Industrial Revolution , from 280 ppm , the level it had for the last 10,000 years leading up to the mid-18th century , to 399 ppm as of 2015 . The present concentration is the highest in at least the past 800,000 years and likely the highest in the past 20 million years . The increase has been caused by anthropogenic sources , particularly the burning of fossil fuels and deforestation . The daily average concentration of atmospheric CO2 at Mauna Loa Observatory first exceeded 400 ppm on 10 May 2013 . It is currently rising at a rate of approximately 2 ppm/year and accelerating . An estimated 30 -- 40 % of the released by humans into the atmosphere dissolves into oceans , rivers and lakes , which contributes to ocean acidification . |
1121 | Arctic | Another consequence of the fast melting Arctic raises the possibility that there may be even worse extreme weather to come, according to a few scientists: titanic Atlantic superstorms and hurricanes barreling across Europe. | Arctic The Arctic ( -LSB- ˈɑrktɪk -RSB- or -LSB- ˈɑrtɪk -RSB- ) is a polar region located at the northernmost part of Earth . The Arctic consists of the Arctic Ocean , adjacent seas , and parts of Alaska ( United States ) , Canada , Finland , Greenland ( Denmark ) , Iceland , Norway , Russia and Sweden . Land within the Arctic region has seasonally varying snow and ice cover , with predominantly treeless permafrost-containing tundra . Arctic seas contain seasonal sea ice in many places . The Arctic region is a unique area among Earth 's ecosystems . For example , the cultures in the region and the Arctic indigenous peoples have adapted to its cold and extreme conditions . In recent years , Arctic sea ice decline has been caused by global warming . Life in the Arctic includes organisms living in the ice , zooplankton and phytoplankton , fish and marine mammals , birds , land animals , plants and human societies . Arctic land is bordered by the subarctic . |
615 | Effects_of_global_warming | If warming temperatures brought on by greenhouse gas emissions make wet years less wet and dry years even drier, as scientists anticipate, year-to-year recovery will become more difficult. | Effects of global warming The effects of global warming are the environmental and social changes caused ( directly or indirectly ) by human emissions of greenhouse gases . There is a scientific consensus that climate change is occurring , and that human activities are the primary driver . Many impacts of climate change have already been observed , including glacier retreat , changes in the timing of seasonal events ( e.g. , earlier flowering of plants ) , and changes in agricultural productivity . Future effects of climate change will vary depending on climate change policies and social development . The two main policies to address climate change are reducing human greenhouse gas emissions ( climate change mitigation ) and adapting to the impacts of climate change . Geoengineering is another policy option . Near-term climate change policies could significantly affect long-term climate change impacts . Stringent mitigation policies might be able to limit global warming ( in 2100 ) to around 2 ° C or below , relative to pre-industrial levels . Without mitigation , increased energy demand and extensive use of fossil fuels might lead to global warming of around 4 ° C. Higher magnitudes of global warming would be more difficult to adapt to , and would increase the risk of negative impacts . |
532 | Carbon_dioxide | Never mind that the emissions of carbon dioxide to make and maintain a wind or solar industrial complex are far greater than they will ever save. | Carbon dioxide Carbon dioxide ( chemical formula ) is a colorless gas with a density about 60 % higher than that of air ( 1.225 g/L ) that is odorless at normally encountered concentrations . Carbon dioxide consists of a carbon atom covalently double bonded to two oxygen atoms . It occurs naturally in Earth 's atmosphere as a trace gas at a concentration of about 0.04 percent ( 400 ppm ) by volume . Natural sources include volcanoes , hot springs and geysers , and it is freed from carbonate rocks by dissolution in water and acids . Because carbon dioxide is soluble in water , it occurs naturally in groundwater , rivers and lakes , ice caps , glaciers and seawater . It is present in deposits of petroleum and natural gas . As the source of available carbon in the carbon cycle , atmospheric carbon dioxide is the primary carbon source for life on Earth and its concentration in Earth 's pre-industrial atmosphere since late in the Precambrian has been regulated by photosynthetic organisms and geological phenomena . Plants , algae and cyanobacteria use light energy to photosynthesize carbohydrate from carbon dioxide and water , with oxygen produced as a waste product . Carbon dioxide is produced by all aerobic organisms when they metabolize carbohydrates and lipids to produce energy by respiration . It is returned to water via the gills of fish and to the air via the lungs of air-breathing land animals , including humans . Carbon dioxide is produced during the processes of decay of organic materials and the fermentation of sugars in bread , beer and winemaking . It is produced by combustion of wood and other organic materials and fossil fuels such as coal , peat , petroleum and natural gas . It is a versatile industrial material , used , for example , as an inert gas in welding and fire extinguishers , as a pressurizing gas in air guns and oil recovery , as a chemical feedstock and in liquid form as a solvent in decaffeination of coffee and supercritical drying . It is added to drinking water and carbonated beverages including beer and sparkling wine to add effervescence . The frozen solid form of , known as `` dry ice '' is used as a refrigerant and as an abrasive in dry-ice blasting . Carbon dioxide is the most significant long-lived greenhouse gas in Earth 's atmosphere . Since the Industrial Revolution anthropogenic emissions - primarily from use of fossil fuels and deforestation - have rapidly increased its concentration in the atmosphere , leading to global warming . Carbon dioxide also causes ocean acidification because it dissolves in water to form carbonic acid . |
677 | Meat | "Which is to say that these beans will be eaten by cows, and the cows will convert the beans to meat, and the humans will eat the meat. | Meat Meat is animal flesh that is eaten as food . Humans have hunted and killed animals for meat since prehistoric times . The advent of civilization allowed the domestication of animals such as chickens , sheep , pigs and cattle . This eventually led to their use in meat production on an industrial scale with the aid of slaughterhouses . Meat is mainly composed of water , protein , and fat . It is edible raw , but is normally eaten after it has been cooked and seasoned or processed in a variety of ways . Unprocessed meat will spoil or rot within hours or days as a result of infection with and decomposition by bacteria and fungi . Most often , meat refers to skeletal muscle and associated fat and other tissues , but it may also describe other edible tissues such as offal . Meat is sometimes also used in a more restrictive sense to mean the flesh of mammalian species ( pigs , cattle , lambs , etc. ) raised and prepared for human consumption , to the exclusion of fish , other seafood , poultry , or other animals . |
3000 | Kīlauea | The influence of the volcano is easily spotted and removed, together with other even more important spurious influences. | Kīlauea Kīlauea ( -LSB- langˌkiːlaʊˈeɪə -RSB- , also -LSB- ˌkɪləˈweɪə -RSB- ; -LSB- tiːlɐwˈwɛjə -RSB- ) is a currently active shield volcano in the Hawaiian Islands , and the most active of the five volcanoes that together form the island of Hawaii . Located along the southern shore of the island , the volcano is between 300,000 and 600,000 years old and emerged above sea level about 100,000 years ago . It is the second youngest product of the Hawaiian hotspot and the current eruptive center of the Hawaiian -- Emperor seamount chain . Because it lacks topographic prominence and its activities historically coincided with those of Mauna Loa , Kīlauea was once thought to be a satellite of its much larger neighbor . Structurally , Kīlauea has a large , fairly recently formed caldera at its summit and two active rift zones , one extending 125 km east and the other 35 km west , as an active fault of unknown depth moving vertically an average of 2 to per year . Kīlauea 's eruptive history has been a long and active one ; its name means `` spewing '' or `` much spreading '' in the Hawaiian language , referring to its frequent outpouring of lava . The earliest lavas from the volcano date back to its submarine preshield stage , samples having been recovered by remotely operated underwater vehicles from its submerged slopes ; samples of other flows have been recovered as core samples . Lavas younger than 1,000 years cover 90 percent of the volcano 's surface . The oldest exposed lavas date back 2,800 years . The first well-documented eruption of Kīlauea occurred in 1823 ( Western contact and written history began in 1778 ) , and since that time the volcano has erupted repeatedly . Most historical eruptions have occurred at the volcano 's summit or its eastern rift zone , and are prolonged and effusive in character . The geological record shows , however , that violent explosive activity predating European contact was extremely common , and in 1790 one such eruption killed over 80 warriors ; should explosive activity start anew the volcano would become much more of a danger to humans . Kīlauea 's current eruption dates back to January 3 , 1983 , and is by far its longest-duration historical period of activity , as well as one of the longest-duration eruptions in the world ; as of January 2011 , the eruption has produced 3.5 km3 of lava and resurfaced 123.2 km2 of land . Kīlauea 's high state of activity has a major impact on its mountainside ecology , where plant growth is often interrupted by fresh tephra and drifting volcanic sulfur dioxide , producing acid rains particularly in a barren area south of its southwestern rift zone known as the Kaʻū Desert . Nonetheless , wildlife flourishes where left undisturbed elsewhere on the volcano and is highly endemic thanks to Kīlauea 's ( and the island of Hawaii 's ) isolation from the nearest landmass . Historically , the five volcanoes on the island were considered sacred by the Hawaiian people , and in Hawaiian mythology Kīlauea 's Halemaumau Crater served as the body and home of Pele , goddess of fire , lightning , wind , and volcanoes . William Ellis , a missionary from England , gave the first modern account of Kīlauea and spent two weeks traveling along the volcano ; since its foundation by Thomas Jaggar in 1912 , the Hawaiian Volcano Observatory , located on the rim of Kīlauea caldera , has served as the principal investigative and scientific body on the volcano and the island in general . In 1916 , a bill forming the Hawaii Volcanoes National Park was signed into law by President Woodrow Wilson ; since then , the park has become a World Heritage Site and a major tourist destination , attracting roughly 2.6 million people annually . |
1468 | 2019–20_Australian_bushfire_season | The bushfires in Australia were caused by arsonists and a series of lightning strikes, not 'climate change'. | 2019–20 Australian bushfire season The 2019–20 Australian bushfire season, colloquially known as Black Summer, was a period of unusually intense bushfires in many parts of Australia. In June 2019, the Queensland Fire and Emergency Service acting director warned of the potential for an early start to the bushfire season which normally starts in August. The warning was based on the Northern Australia bushfire seasonal outlook noting exceptional dry conditions and a lack of soil moisture, combined with early fires in central Queensland. Throughout the summer, hundreds of fires burnt, mainly in the southeast of the country. The major fires peaked during December–January. As of 9 March 2020, the fires burnt an estimated 18.6 million hectares (46 million acres; 186,000 square kilometres; 72,000 square miles), destroyed over 5,900 buildings (including 2,779 homes) and killed at least 34 people. Nearly three billion terrestrial vertebrates alone – the vast majority being reptiles – were affected and some endangered species were believed to be driven to extinction. At its peak, air quality dropped to hazardous levels in all southern and eastern states. The cost of dealing with the bushfires is expected to exceed the A$4.4 billion of the 2009 Black Saturday fires, and tourism sector revenues fell by more than A$1 billion. However, economists estimated that the Australian bushfires may cost over A$103 billion in property damage and economic losses, making the bushfires Australia's costliest natural disaster to date. Nearly 80 percent of Australians were affected either directly or indirectly by the bushfires. By 7 January 2020, the smoke had moved approximately 11,000 kilometres (6,800 mi) across the South Pacific Ocean to Chile and Argentina. As of 2 January 2020, NASA estimated that 306 million tonnes (337 million short tons) of CO2 had been emitted.From September 2019 to March 2020, fires heavily impacted various regions of the state of New South Wales. In eastern and north-eastern Victoria large areas of forest burnt out of control for four weeks before the fires emerged from the forests in late December. Multiple states of emergency were declared across New South Wales, Victoria, and the Australian Capital Territory. Reinforcements from all over Australia were called in to assist fighting the fires and relieve exhausted local crews in New South Wales. The Australian Defence Force was mobilised to provide air support to the firefighting effort and to provide manpower and logistical support. Firefighters, supplies and equipment from Canada, New Zealand, Singapore and the United States, among others, helped fight the fires, especially in New South Wales.During the ensuing crisis, an air tanker and two helicopters crashed during firefighting operations, the air tanker crash resulting in the deaths of the three crew. Two fire trucks were caught in fatal incidents caused directly by fire conditions, killing three fire fighters.By 4 March 2020, all fires in New South Wales had been extinguished completely (to the point where there were no fires in the state for the first time since July 2019), and the Victoria fires had all been contained. The last fire of the season occurred in Lake Clifton, Western Australia, in early May.There has been considerable debate regarding the underlying cause of the intensity and scale of the fires, including the role of fire management practices and climate change, which during the peak of the crisis attracted significant international attention. Politicians visiting fire impacted areas received mixed responses, in particular Prime Minister Scott Morrison. An estimated A$500 million was donated by the public at large, international organisations, public figures and celebrities for victim relief and wildlife recovery. Convoys of donated food, clothing and livestock feed were sent to affected areas. |
1715 | Scientific_modelling | Theory, models and direct measurement confirm CO2 is currently the main driver of climate change. | Scientific modelling Scientific modelling is a scientific activity , the aim of which is to make a particular part or feature of the world easier to understand , define , quantify , visualize , or simulate by referencing it to existing and usually commonly accepted knowledge . It requires selecting and identifying relevant aspects of a situation in the real world and then using different types of models for different aims , such as conceptual models to better understand , operational models to operationalize , mathematical models to quantify , and graphical models to visualize the subject . Modelling is an essential and inseparable part of many scientific disciplines , each of which have their own ideas about specific types of modelling . There is also an increasing attention to scientific modelling in fields such as science education , philosophy of science , systems theory , and knowledge visualization . There is growing collection of methods , techniques and meta-theory about all kinds of specialized scientific modelling . |
2054 | Climate_sensitivity | During the period 1940 to 1976 there was a cooling of the climate despite increasing CO2 levels. | Climate sensitivity Climate sensitivity is the equilibrium temperature change in response to changes of the radiative forcing . Therefore , climate sensitivity depends on the initial climate state , but potentially can be accurately inferred from precise palaeoclimate data . Slow climate feedbacks , especially changes of ice sheet size and atmospheric CO2 , amplify the total Earth system sensitivity by an amount that depends on the time scale considered . Although climate sensitivity is usually used in the context of radiative forcing by carbon dioxide ( CO2 ) , it is thought of as a general property of the climate system : the change in surface air temperature ( ΔTs ) following a unit change in radiative forcing ( RF ) , and thus is expressed in units of ° C / ( W/m2 ) . For this to be useful , the measure must be independent of the nature of the forcing ( e.g. from greenhouse gases or solar variation ) ; to first order this is indeed found to be so . The climate sensitivity specifically due to is often expressed as the temperature change in ° C associated with a doubling of the concentration of carbon dioxide in Earth 's atmosphere . For coupled atmosphere-ocean global climate models ( e.g. CMIP5 ) the climate sensitivity is an emergent property : it is not a model parameter , but rather a result of a combination of model physics and parameters . By contrast , simpler energy-balance models may have climate sensitivity as an explicit parameter . The terms represented in the equation relate radiative forcing ( RF ) to linear changes in global surface temperature change ( ΔTs ) via the climate sensitivity λ . It is also possible to estimate climate sensitivity from observations ; however , this is difficult due to uncertainties in the forcing and temperature histories . |
770 | Greenhouse_gas | [CO2] has increased 43 percent above the pre-industrial level so far | Greenhouse gas A greenhouse gas ( abbrev . GHG ) is a gas in an atmosphere that absorbs and emits radiation within the thermal infrared range . This process is the fundamental cause of the greenhouse effect . The primary greenhouse gases in Earth 's atmosphere are water vapor , carbon dioxide , methane , nitrous oxide , and ozone . Without greenhouse gases , the average temperature of Earth 's surface would be about -18 ° C , rather than the present average of 15 ° C . In the Solar System , the atmospheres of Venus , Mars and Titan also contain gases that cause a greenhouse effect . Human activities since the beginning of the Industrial Revolution ( taken as the year 1750 ) have produced a 40 % increase in the atmospheric concentration of carbon dioxide , from 280 ppm in 1750 to 406 ppm in early 2017 . This increase has occurred despite the uptake of a large portion of the emissions by various natural `` sinks '' involved in the carbon cycle . Anthropogenic carbon dioxide emissions ( i.e. , emissions produced by human activities ) come from combustion of fossil fuels , principally coal , oil , and natural gas , along with deforestation , soil erosion and animal agriculture . It has been estimated that if greenhouse gas emissions continue at the present rate , Earth 's surface temperature could exceed historical values as early as 2047 , with potentially harmful effects on ecosystems , biodiversity and the livelihoods of people worldwide . Recent estimates suggest that on the current emissions trajectory the Earth could pass a threshold of 2 ° C global warming , which the United Nations ' IPCC designated as the upper limit to avoid `` dangerous '' global warming , by 2036 . |
2453 | Silurian | "The killer proof that CO2 does not drive climate is to be found during the Ordovician- Silurian and the Jurassic-Cretaceous periods when CO2 levels were greater than 4000 ppmv (parts per million by volume) and about 2000 ppmv respectively. | Silurian The Silurian is a geologic period and system spanning 24.6 million years from the end of the Ordovician Period , at million years ago ( Mya ) , to the beginning of the Devonian Period , Mya . As with other geologic periods , the rock beds that define the period 's start and end are well identified , but the exact dates are uncertain by several million years . The base of the Silurian is set at a major Ordovician-Silurian extinction event when 60 % of marine species were wiped out . A significant evolutionary milestone during the Silurian was the diversification of jawed and bony fish . Multi-cellular life also began to appear on land in the form of small , bryophyte-like and vascular plants that grew beside lakes , streams , and coastlines , and terrestrial arthropods are also first found on land during the Silurian . However , terrestrial life would not greatly diversify and affect the landscape until the Devonian . |
1342 | Scientific_consensus_on_climate_change | The worsening of tidal flooding in American coastal communities is largely a consequence of greenhouse gases from human activity, and the problem will grow far worse in coming decades, scientists reported Monday. | Scientific consensus on climate change There is currently a strong scientific consensus that the Earth is warming and that this warming is mainly caused by human activities. This consensus is supported by various studies of scientists' opinions and by position statements of scientific organizations, many of which explicitly agree with the Intergovernmental Panel on Climate Change (IPCC) synthesis reports. Nearly all actively publishing climate scientists (97–98%) support the consensus on anthropogenic climate change, and the remaining 2% of contrarian studies either cannot be replicated or contain errors. |
615 | Global_warming | If warming temperatures brought on by greenhouse gas emissions make wet years less wet and dry years even drier, as scientists anticipate, year-to-year recovery will become more difficult. | Global warming Global warming , also referred to as climate change , is the observed century-scale rise in the average temperature of the Earth 's climate system and its related effects . Multiple lines of scientific evidence show that the climate system is warming . Many of the observed changes since the 1950s are unprecedented in the instrumental temperature record which extends back to the mid 19th century , and in paleoclimate proxy records over thousands of years . In 2013 , the Intergovernmental Panel on Climate Change ( IPCC ) Fifth Assessment Report concluded that `` It is extremely likely that human influence has been the dominant cause of the observed warming since the mid-20th century . '' The largest human influence has been emission of greenhouse gases such as carbon dioxide , methane and nitrous oxide . Climate model projections summarized in the report indicated that during the 21st century the global surface temperature is likely to rise a further 0.3 to for their lowest emissions scenario and 2.6 to for the highest emissions scenario . These findings have been recognized by the national science academies of the major industrialized nations and are not disputed by any scientific body of national or international standing . Future climate change and associated impacts will differ from region to region around the globe . Anticipated effects include warming global temperature , rising sea levels , changing precipitation , and expansion of deserts in the subtropics . Warming is expected to be greater over land than over the oceans and greatest in the Arctic , with the continuing retreat of glaciers , permafrost and sea ice . Other likely changes include more frequent extreme weather events including heat waves , droughts , heavy rainfall with floods and heavy snowfall ; ocean acidification ; and species extinctions due to shifting temperature regimes . Effects significant to humans include the threat to food security from decreasing crop yields and the abandonment of populated areas due to rising sea levels . Because the climate system has a large `` inertia '' and greenhouse gases will stay in the atmosphere for a long time , many of these effects will not only exist for decades or centuries , but will persist for tens of thousands of years . Possible societal responses to global warming include mitigation by emissions reduction , adaptation to its effects , building systems resilient to its effects , and possible future climate engineering . Most countries are parties to the United Nations Framework Convention on Climate Change ( UNFCCC ) , whose ultimate objective is to prevent dangerous anthropogenic climate change . Parties to the UNFCCC have agreed that deep cuts in emissions are required and that global warming should be limited to well below 2.0 C-change relative to pre-industrial levels , with efforts made to limit warming to 1.5 C-change . Public reactions to global warming and concern about its effects are also increasing . A global 2015 Pew Research Center report showed a median of 54 % consider it `` a very serious problem '' . There are significant regional differences , with Americans and Chinese ( whose economies are responsible for the greatest annual CO2 emissions ) among the least concerned . |
1559 | Cloud | Clouds provide negative feedback. | Cloud In meteorology , a cloud is an aerosol comprising a visible mass of minute liquid droplets , frozen crystals , or particles suspended in the atmosphere above the surface of a planetary body . The droplets and crystals may be made of water or various chemicals . On Earth , clouds are formed as a result of saturation of the air when it is cooled to its dew point , or when it gains sufficient moisture ( usually in the form of water vapor ) from an adjacent source to raise the dew point to the ambient temperature . They are seen in the Earth 's homosphere ( which includes the troposphere , stratosphere , and mesosphere ) . Nephology is the science of clouds which is undertaken in the cloud physics branch of meteorology . There are two systems of naming clouds in their respective layers of the atmosphere ; Latin in the troposphere and mostly alpha-numeric above the troposphere . Cloud types in the troposphere , the atmospheric layer closest to Earth 's surface , have Latin names due to the universal adaptation of Luke Howard 's nomenclature . Formally proposed in 1802 , it became the basis of a modern international system that classifies clouds into five physical forms and three altitude levels ( formerly known as étages ) . These physical types , in approximate ascending order of convective activity , include stratiform sheets , cirriform wisps and patches , stratocumuliform layers ( mainly structured as rolls , ripples , and patches ) , cumuliform heaps , and very large cumulonimbiform heaps that often show complex structure . The physical forms are cross-classified by the altitude levels to produce ten basic genus-types , most of which can be divided into species , and subdivided into varieties . Two cirriform clouds that form higher up in the stratosphere and mesosphere have common names for their main types , but are sub-classified alpha-numerically . They are relatively uncommon and are mostly seen in the polar regions of Earth . Clouds have been observed in the atmospheres of other planets and moons in the Solar System and beyond . However , due to their different temperature characteristics , they are often composed of other substances such as methane , ammonia , and sulfuric acid as well as water . Homospheric types determined by cross-classification of forms and levels . '' Homospheric types include the ten tropospheric genera and two additional major types above the troposphere . The cumulus genus includes three variants as defined by vertical size . |
1603 | Climate_change_in_Tuvalu | Coral atolls grow as sea levels rise. | Climate change in Tuvalu Global warming (recent climate change) is particularly threatening in Tuvalu. This is because the average height of the islands is less than 2 metres (6.6 ft) above sea level, with the highest point of Niulakita being about 4.6 metres (15 ft) above sea level. Between 1971 and 2014, during a period of global warming, Tuvalu islands have increased in size, according to aerial photography and satellite imagery. Over four decades, there was a net increase in land area in Tuvalu of 73.5 ha (2.9%), although the changes were not uniform, with 74% of land increasing in size and 27% of land decreasing in size. The sea level at the Funafuti tide gauge has risen at 3.9 mm per year, which is approximately twice the global average.Tuvalu could be one of the first nations to be significantly impacted by rising sea levels. Not only could parts of the island be flooded but the rising saltwater table could also destroy deep rooted food crops such as coconut, pulaka, and taro. Research from the University of Auckland suggests that Tuvalu may remain habitable over the next century. However, as of March 2018, Prime Minister Enele Sopoaga stated that Tuvalu is not expanding and has gained no additional habitable land. Sopoaga has also said that evacuating the islands is the last resort. |
1968 | Daylight_saving_time_in_the_United_States | The 2007's early start to Daylight Saving Time contributed to global warming. | Daylight saving time in the United States Daylight saving time in the United States is the practice of setting the clock forward by one hour during the warmer part of the year , so that evenings have more daylight and mornings have less . Most areas of the United States observe daylight saving time ( DST ) , the exceptions being Arizona ( except for the Navajo , who do observe daylight saving time on tribal lands ) , Hawaii , and the overseas territories of American Samoa , Guam , the Northern Mariana Islands , Puerto Rico , and the United States Virgin Islands . In general , daylight time is not observed in lower-latitude regions , as summer days are not much longer than winter ones as in higher latitudes , so the advantage of the change is smaller . Daylight saving time starts on the second Sunday in March and ends on the first Sunday in November , with the time changes taking place at 2:00 a.m. local time . With a mnemonic word play referring to seasons , clocks `` spring forward and fall back '' -- that is , in springtime the clocks are moved forward from 2:00 a.m. to 3:00 a.m. , and in fall they are moved back from 2:00 a.m. to 1:00 a.m. Daylight saving time lasts for a total of 34 weeks ( 238 days ) every year , about 65 % of the entire year ( including leap years ) . The following table lists recent past and near future starting and ending dates of daylight saving time in the United States : |
967 | Ice_age | He said: 'We have had five warming cycles since about 900AD, each followed by a dramatic cooling cycle.' | Ice age An ice age is a period of long-term reduction in the temperature of Earth 's surface and atmosphere , resulting in the presence or expansion of continental and polar ice sheets and alpine glaciers . Within a long-term ice age , individual pulses of cold climate are termed `` glacial periods '' ( or alternatively `` glacials '' or `` glaciations '' or colloquially as `` ice age '' ) , and intermittent warm periods are called `` interglacials '' . In the terminology of glaciology , ice age implies the presence of extensive ice sheets in both northern and southern hemispheres . By this definition , we are in an interglacial period -- the Holocene -- of the ice age . The ice age began 2.6 million years ago at the start of the Pleistocene epoch , because the Greenland , Arctic , and Antarctic ice sheets still exist . |
2738 | Hockey_stick_controversy | When you read Phil Jones' actual words, you see he's saying there is a warming trend | Hockey stick controversy In the hockey stick controversy , the data and methods used in reconstructions of the temperature record of the past 1000 years have been disputed . Reconstructions have consistently shown that the rise in the instrumental temperature record of the past 150 years is not matched in earlier centuries , and the name `` hockey stick graph '' was coined for figures showing a long-term decline followed by an abrupt rise in temperatures . These graphs were publicised to explain the scientific findings of climatology , and in addition to scientific debate over the reconstructions , they have been the topic of political dispute . The issue is part of the global warming controversy and has been one focus of political responses to reports by the Intergovernmental Panel on Climate Change ( IPCC ) . Arguments over the reconstructions have been taken up by fossil fuel industry funded lobbying groups attempting to cast doubt on climate science . The use of proxy indicators to get quantitative estimates of the temperature record of past centuries was developed from the 1990s onwards , and found indications that recent warming was exceptional . The reconstruction introduced the `` Composite Plus Scaling '' ( CPS ) method used by most later large-scale reconstructions , and its findings were disputed by Patrick Michaels at the United States House Committee on Science . In 1998 , Michael E. Mann , Raymond S. Bradley and Malcolm K. Hughes developed new statistical techniques to produce ( MBH98 ) , the first eigenvector-based climate field reconstruction ( CFR ) . This showed global patterns of annual surface temperature , and included a graph of average hemispheric temperatures back to 1400 . In ( MBH99 ) the methodology was extended back to 1000 . The term hockey stick was coined by the climatologist Jerry D. Mahlman , to describe the pattern this showed , envisaging a graph that is relatively flat to 1900 as forming an ice hockey stick 's `` shaft '' , followed by a sharp increase corresponding to the `` blade '' . A version of this graph was featured prominently in the 2001 IPCC Third Assessment Report ( TAR ) , along with four other reconstructions supporting the same conclusion . The graph was publicised , and became a focus of dispute for those opposed to the strengthening scientific consensus that late 20th-century warmth was exceptional . Those disputing the graph included Pat Michaels , the George C. Marshall Institute and Fred Singer . A paper by Willie Soon and Sallie Baliunas claiming greater medieval warmth was used by the Bush administration chief of staff Philip Cooney to justify altering the first Environmental Protection Agency Report on the Environment . The paper was quickly dismissed by scientists in the Soon and Baliunas controversy , but on July 28 , Republican Jim Inhofe spoke in the Senate citing it to claim `` that man-made global warming is the greatest hoax ever perpetrated on the American people '' . Later in 2003 , a paper by Steve McIntyre and Ross McKitrick disputing the data used in MBH98 paper was publicised by the George C. Marshall Institute and the Competitive Enterprise Institute . In 2004 , Hans von Storch published criticism of the statistical techniques as tending to underplay variations in earlier parts of the graph , though this was disputed and he later accepted that the effect was very small . In 2005 , McIntyre and McKitrick published criticisms of the principal component analysis methodology as used in MBH98 and MBH99 . The analysis therein was subsequently disputed by published papers , including and , which pointed to errors in the McIntyre and McKitrick methodology . In June 2005 , Rep. Joe Barton launched what Sherwood Boehlert , chairman of the House Science Committee , called a `` misguided and illegitimate investigation '' into the data , methods and personal information of Mann , Bradley and Hughes . At Boehlert 's request , a panel of scientists convened by the National Research Council was set up , which reported in 2006 , supporting Mann 's findings with some qualifications , including agreeing that there were some statistical failings but these had little effect on the result . Barton and U.S. Rep. Ed Whitfield requested Edward Wegman to set up a team of statisticians to investigate , and they supported McIntyre and McKitrick 's view that there were statistical failings , although they did not quantify whether there was any significant effect . They also produced an extensive network analysis which has been discredited by expert opinion and found to have issues of plagiarism . Arguments against the MBH studies were reintroduced as part of the Climatic Research Unit email controversy , but dismissed by eight independent investigations . More than two dozen reconstructions , using various statistical methods and combinations of proxy records , have supported the broad consensus shown in the original 1998 hockey-stick graph , with variations in how flat the pre-20th century `` shaft '' appears . The 2007 IPCC Fourth Assessment Report cited 14 reconstructions , 10 of which covered 1,000 years or longer , to support its strengthened conclusion that it was likely that Northern Hemisphere temperatures during the 20th century were the highest in at least the past 1,300 years . Over a dozen subsequent reconstructions , including Mann et al. 2008 and , have supported these general conclusions . |
1507 | Climatic_Research_Unit_email_controversy | Global warming' is a myth — so say 80 graphs from 58 peer-reviewed scientific papers published in 2017. | Climatic Research Unit email controversy The Climatic Research Unit email controversy ( also known as `` Climategate '' ) began in November 2009 with the hacking of a server at the Climatic Research Unit ( CRU ) at the University of East Anglia ( UEA ) by an external attacker , copying thousands of emails and computer files , the Climatic Research Unit documents , to various internet locations several weeks before the Copenhagen Summit on climate change . The story was first broken by climate change denialists with columnist James Delingpole popularising the term `` Climategate '' to describe the controversy . Several people considered climate change `` skeptics '' argued that the emails showed global warming was a scientific conspiracy , that scientists manipulated climate data and attempted to suppress critics . The CRU rejected this , saying the emails had been taken out of context and merely reflected an honest exchange of ideas . The mainstream media picked up the story as negotiations over climate change mitigation began in Copenhagen on 7 December 2009 . Because of the timing , scientists , policy makers and public relations experts said that the release of emails was a smear campaign intended to undermine the climate conference . In response to the controversy , the American Association for the Advancement of Science ( AAAS ) , the American Meteorological Society ( AMS ) and the Union of Concerned Scientists ( UCS ) released statements supporting the scientific consensus that the Earth 's mean surface temperature had been rising for decades , with the AAAS concluding , `` based on multiple lines of scientific evidence that global climate change caused by human activities is now underway ... it is a growing threat to society . '' Eight committees investigated the allegations and published reports , finding no evidence of fraud or scientific misconduct . However , the reports called on the scientists to avoid any such allegations in the future by taking steps to regain public confidence in their work , for example by opening up access to their supporting data , processing methods and software , and by promptly honouring freedom of information requests . The scientific consensus that global warming is occurring as a result of human activity remained unchanged throughout the investigations . |
2613 | Carbon_dioxide_in_Earth's_atmosphere | CO2 levels are measured by hundreds of stations scattered across 66 countries which all report the same rising trend. | Carbon dioxide in Earth's atmosphere Carbon dioxide is an important trace gas in Earth 's atmosphere . Currently it constitutes about 0.041 % ( equal to 410 parts per million ; ppm ) by volume of the atmosphere . Despite its relatively small concentration is a potent greenhouse gas and plays a vital role in regulating Earth 's surface temperature through radiative forcing and the greenhouse effect . Reconstructions show that concentrations of in the atmosphere have varied , ranging from as high as 7,000 ppm during the Cambrian period about 500 million years ago to as low as 180 ppm during the Quaternary glaciation of the last two million years . Carbon dioxide is an integral part of the carbon cycle , a biogeochemical cycle in which carbon is exchanged between the Earth 's oceans , soil , rocks and the biosphere . Plants and other photoautotrophs use solar energy to produce carbohydrate from atmospheric carbon dioxide and water by photosynthesis . Almost all other organisms depend on carbohydrate derived from photosynthesis as their primary source of energy and carbon compounds . The current episode of global warming is attributed to increasing emissions of and other greenhouse gases into Earth 's atmosphere . The global annual mean concentration of in the atmosphere has increased by more than 40 % since the start of the Industrial Revolution , from 280 ppm , the level it had for the last 10,000 years leading up to the mid-18th century , to 399 ppm as of 2015 . The present concentration is the highest in at least the past 800,000 years and likely the highest in the past 20 million years . The increase has been caused by anthropogenic sources , particularly the burning of fossil fuels and deforestation . The daily average concentration of atmospheric CO2 at Mauna Loa Observatory first exceeded 400 ppm on 10 May 2013 . It is currently rising at a rate of approximately 2 ppm/year and accelerating . An estimated 30 -- 40 % of the released by humans into the atmosphere dissolves into oceans , rivers and lakes , which contributes to ocean acidification . |
31 | Carbon_tax | Discovery Of Massive Volcanic CO2 Emissions Discredits Global Warming Theory | Carbon tax A carbon tax is a tax levied on the carbon content of fuels . It is a form of carbon pricing . Carbon is present in every hydrocarbon fuel ( coal , petroleum , and natural gas ) and converted to carbon dioxide and other products when combusted . In contrast , non-combustion energy sources -- wind , sunlight , geothermal , hydropower , and nuclear -- do not convert hydrocarbons to . is a heat-trapping `` greenhouse '' gas which represents a negative externality on the climate system ( see scientific opinion on global warming ) . Since GHG emissions caused by the combustion of fossil fuels are closely related to the carbon content of the respective fuels , a tax on these emissions can be levied by taxing the carbon content of fossil fuels at any point in the product cycle of the fuel . Carbon tax offers social and economic benefits . It is a tax that increases revenue without significantly altering the economy while simultaneously promoting objectives of climate change policy . The objective of a carbon tax is to reduce the harmful and unfavorable levels of carbon dioxide emissions , thereby decelerating climate change and its negative effects on the environment and human health . Carbon taxes offer a potentially cost-effective means of reducing greenhouse gas emissions . From an economic perspective , carbon taxes are a type of Pigovian tax . They help to address the problem of emitters of greenhouse gases not facing the full social cost of their actions . Carbon taxes can be a regressive tax , in that they may directly or indirectly affect low-income groups disproportionately . The regressive impact of carbon taxes could be addressed by using tax revenues to favour low-income groups . A number of countries have implemented carbon taxes or energy taxes that are related to carbon content . Most environmentally related taxes with implications for greenhouse gas emissions in OECD countries are levied on energy products and motor vehicles , rather than on emissions directly . Opposition to increased environmental regulation such as carbon taxes often centers on concerns that firms might relocate and/or people might lose their jobs . It has been argued , however , that carbon taxes are more efficient than direct regulation and may even lead to higher employment ( see footnotes ) . Many large users of carbon resources in electricity generation , such as the United States , Russia , and China , are resisting carbon taxation . |
173 | Coal | If there were [carbon emissions], we could not see because most carbon is black. | Coal Coal is a combustible black or brownish-black sedimentary rock usually occurring in rock strata in layers or veins called coal beds or coal seams . The harder forms , such as anthracite coal , can be regarded as metamorphic rock because of later exposure to elevated temperature and pressure . Coal is composed primarily of carbon , along with variable quantities of other elements , chiefly hydrogen , sulfur , oxygen , and nitrogen . A fossil fuel , coal forms when dead plant matter is converted into peat , which in turn is converted into lignite , then sub-bituminous coal , after that bituminous coal , and lastly anthracite . This involves biological and geological processes that take place over time . Throughout human history , coal has been used as an energy resource , primarily burned for the production of electricity and heat , and is also used for industrial purposes , such as refining metals . Coal is the largest source of energy for the generation of electricity worldwide , as well as one of the largest worldwide anthropogenic sources of carbon dioxide releases . The extraction of coal , its use in energy production and its byproducts are all associated with environmental and health effects including climate change . Coal is extracted from the ground by coal mining . Since 1983 , the world 's top coal producer has been China . In 2015 China produced 3,747 million tonnes of coal -- 47.7 % of 7,861 million tonnes world coal production . In 2015 other large producers were United States ( 813 million tonnes ) , India ( 678 ) , European Union ( 539 ) and Australia ( 503 ) . In 2010 the largest exporters were Australia with 328 million tonnes ( 27.1 % of world coal export ) and Indonesia with 316 million tonnes ( 26.1 % ) , while the largest importers were Japan with 207 million tonnes ( 17.5 % of world coal import ) , China with 195 million tonnes ( 16.6 % ) and South Korea with 126 million tonnes ( 10.7 % ) . |
1644 | Glacier | Most glaciers are retreating, posing a serious problem for millions who rely on glaciers for water. | Glacier A glacier ( -LSB- pronˈɡleɪʃər -RSB- or -LSB- ˈɡlæsiə -RSB- ) is a persistent body of dense ice that is constantly moving under its own weight ; it forms where the accumulation of snow exceeds its ablation ( melting and sublimation ) over many years , often centuries . Glaciers slowly deform and flow due to stresses induced by their weight , creating crevasses , seracs , and other distinguishing features . They also abrade rock and debris from their substrate to create landforms such as cirques and moraines . Glaciers form only on land and are distinct from the much thinner sea ice and lake ice that form on the surface of bodies of water . On Earth , 99 % of glacial ice is contained within vast ice sheets in the polar regions , but glaciers may be found in mountain ranges on every continent except Australia , and on a few high-latitude oceanic islands . Between 35 ° N and 35 ° S , glaciers occur only in the Himalayas , Andes , Rocky Mountains , a few high mountains in East Africa , Mexico , New Guinea and on Zard Kuh in Iran . Glaciers cover about 10 percent of Earth 's land surface . Continental glaciers cover nearly 5 e6sqmi or about 98 percent of Antarctica 's 5.1 e6sqmi , with an average thickness of 7,000 ft. Greenland and Patagonia also have huge expanses of continental glaciers . Glacial ice is the largest reservoir of fresh water on Earth . Many glaciers from temperate , alpine and seasonal polar climates store water as ice during the colder seasons and release it later in the form of meltwater as warmer summer temperatures cause the glacier to melt , creating a water source that is especially important for plants , animals and human uses when other sources may be scant . Within high altitude and Antarctic environments , the seasonal temperature difference is often not sufficient to release meltwater . Because glacial mass is affected by long-term climatic changes , e.g. , precipitation , mean temperature , and cloud cover , glacial mass changes are considered among the most sensitive indicators of climate change and are a major source of variations in sea level . A large piece of compressed ice , or a glacier , appears blue as large quantities of water appear blue . This is because water molecules absorb other colors more efficiently than blue . The other reason for the blue color of glaciers is the lack of air bubbles . Air bubbles , which give a white color to ice , are squeezed out by pressure increasing the density of the created ice . |
2914 | Arctic_Ocean | Whatever is driving increases in winter Arctic temperatures is not heat coming out of the Arctic Ocean, which is covered with insulating ice.' | Arctic Ocean The Arctic Ocean is the smallest and shallowest of the world 's five major oceans . The International Hydrographic Organization ( IHO ) recognizes it as an ocean , although some oceanographers call it the Arctic Mediterranean Sea or simply the Arctic Sea , classifying it a mediterranean sea or an estuary of the Atlantic Ocean . Alternatively , the Arctic Ocean can be seen as the northernmost part of the all-encompassing World Ocean . Located mostly in the Arctic north polar region in the middle of the Northern Hemisphere , the Arctic Ocean is almost completely surrounded by Eurasia and North America . It is partly covered by sea ice throughout the year and almost completely in winter . The Arctic Ocean 's surface temperature and salinity vary seasonally as the ice cover melts and freezes ; its salinity is the lowest on average of the five major oceans , due to low evaporation , heavy fresh water inflow from rivers and streams , and limited connection and outflow to surrounding oceanic waters with higher salinities . The summer shrinking of the ice has been quoted at 50 % . The US National Snow and Ice Data Center ( NSIDC ) uses satellite data to provide a daily record of Arctic sea ice cover and the rate of melting compared to an average period and specific past years . |
2631 | Fahrenheit | The temperatures are expected to change by as much as 10 Fahrenheit degrees at different places of the globe. | Fahrenheit Fahrenheit is a temperature scale based on one proposed in 1724 by Amsterdam-based physicist Daniel Gabriel Fahrenheit ( 1686 -- 1736 ) , after whom the scale is named . It uses the degree Fahrenheit ( symbol ° F ) as the unit . Several accounts of how he originally defined his scale exist . The lower defining point , 0 ° F , was established as the temperature of a solution of brine made from equal parts of ice and salt . Further limits were established as the melting point of ice ( 32 ° F ) and his best estimate of the average human body temperature ( 96 ° F , about 2.6 ° F less than the modern value due to a later redefinition of the scale ) . The scale is now usually defined by two fixed points : the temperature at which water freezes into ice is defined as 32 ° F , and the boiling point of water is defined to be 212 ° F , a 180 ° F separation , as defined at sea level and standard atmospheric pressure . By the end of the 20th century , Fahrenheit was used as the official temperature scale only in the United States ( including its unincorporated territories ) , its freely associated states in the Western Pacific ( Palau , the Federated States of Micronesia and the Marshall Islands ) , the Bahamas , Belize , and the Cayman Islands . All other countries in the world now use the Celsius scale , defined since 1954 by absolute zero being − 273.15 ° C and the triple point of water being at 0.01 ° C. |
195 | Carbon_dioxide | Carbon dioxide is a non-condensable atmospheric gas like nitrogen and oxygen | Carbon dioxide Carbon dioxide ( chemical formula ) is a colorless gas with a density about 60 % higher than that of air ( 1.225 g/L ) that is odorless at normally encountered concentrations . Carbon dioxide consists of a carbon atom covalently double bonded to two oxygen atoms . It occurs naturally in Earth 's atmosphere as a trace gas at a concentration of about 0.04 percent ( 400 ppm ) by volume . Natural sources include volcanoes , hot springs and geysers , and it is freed from carbonate rocks by dissolution in water and acids . Because carbon dioxide is soluble in water , it occurs naturally in groundwater , rivers and lakes , ice caps , glaciers and seawater . It is present in deposits of petroleum and natural gas . As the source of available carbon in the carbon cycle , atmospheric carbon dioxide is the primary carbon source for life on Earth and its concentration in Earth 's pre-industrial atmosphere since late in the Precambrian has been regulated by photosynthetic organisms and geological phenomena . Plants , algae and cyanobacteria use light energy to photosynthesize carbohydrate from carbon dioxide and water , with oxygen produced as a waste product . Carbon dioxide is produced by all aerobic organisms when they metabolize carbohydrates and lipids to produce energy by respiration . It is returned to water via the gills of fish and to the air via the lungs of air-breathing land animals , including humans . Carbon dioxide is produced during the processes of decay of organic materials and the fermentation of sugars in bread , beer and winemaking . It is produced by combustion of wood and other organic materials and fossil fuels such as coal , peat , petroleum and natural gas . It is a versatile industrial material , used , for example , as an inert gas in welding and fire extinguishers , as a pressurizing gas in air guns and oil recovery , as a chemical feedstock and in liquid form as a solvent in decaffeination of coffee and supercritical drying . It is added to drinking water and carbonated beverages including beer and sparkling wine to add effervescence . The frozen solid form of , known as `` dry ice '' is used as a refrigerant and as an abrasive in dry-ice blasting . Carbon dioxide is the most significant long-lived greenhouse gas in Earth 's atmosphere . Since the Industrial Revolution anthropogenic emissions - primarily from use of fossil fuels and deforestation - have rapidly increased its concentration in the atmosphere , leading to global warming . Carbon dioxide also causes ocean acidification because it dissolves in water to form carbonic acid . |
2256 | Carbon_dioxide_in_Earth's_atmosphere | The warming effect from more CO2 greatly outstrips the influence from changes in the Earth's orbit or solar activity, even if solar levels were to drop to Maunder Minimum levels. | Carbon dioxide in Earth's atmosphere Carbon dioxide is an important trace gas in Earth 's atmosphere . Currently it constitutes about 0.041 % ( equal to 410 parts per million ; ppm ) by volume of the atmosphere . Despite its relatively small concentration is a potent greenhouse gas and plays a vital role in regulating Earth 's surface temperature through radiative forcing and the greenhouse effect . Reconstructions show that concentrations of in the atmosphere have varied , ranging from as high as 7,000 ppm during the Cambrian period about 500 million years ago to as low as 180 ppm during the Quaternary glaciation of the last two million years . Carbon dioxide is an integral part of the carbon cycle , a biogeochemical cycle in which carbon is exchanged between the Earth 's oceans , soil , rocks and the biosphere . Plants and other photoautotrophs use solar energy to produce carbohydrate from atmospheric carbon dioxide and water by photosynthesis . Almost all other organisms depend on carbohydrate derived from photosynthesis as their primary source of energy and carbon compounds . The current episode of global warming is attributed to increasing emissions of and other greenhouse gases into Earth 's atmosphere . The global annual mean concentration of in the atmosphere has increased by more than 40 % since the start of the Industrial Revolution , from 280 ppm , the level it had for the last 10,000 years leading up to the mid-18th century , to 399 ppm as of 2015 . The present concentration is the highest in at least the past 800,000 years and likely the highest in the past 20 million years . The increase has been caused by anthropogenic sources , particularly the burning of fossil fuels and deforestation . The daily average concentration of atmospheric CO2 at Mauna Loa Observatory first exceeded 400 ppm on 10 May 2013 . It is currently rising at a rate of approximately 2 ppm/year and accelerating . An estimated 30 -- 40 % of the released by humans into the atmosphere dissolves into oceans , rivers and lakes , which contributes to ocean acidification . |
630 | Snow | I conclude that it must be ice accumulation, through evaporation of ocean water, and subsequent precipitation turning into ice. | Snow Snow pertains to frozen crystalline water throughout its life cycle , starting when it precipitates from clouds and accumulates on surfaces , then metamorphoses in place , and ultimately melts , slides or sublimates away . Snowstorms organize and develop by feeding on sources of atmospheric moisture and cold air . Snowflakes nucleate around particles in the atmosphere by attracting supercooled water droplets , which freeze in hexagonal-shaped crystals . Snowflakes take on a variety of shapes , basic among these are platelets , needles , columns and rime . As snow accumulates into a snowpack , it may blow into drifts . Over time , accumulated snow metamorphoses , by sintering , sublimation and freeze-thaw . Where the climate is cold enough for year-to-year accumulation , a glacier may form . Otherwise , snow typically melts seasonally , causing runoff into streams and rivers and recharging groundwater . Major snow-prone areas include the polar regions , the upper half of the Northern Hemisphere and mountainous regions worldwide with sufficient moisture and cold temperatures . In the Southern Hemisphere , snow is confined primarily to mountainous areas , apart from Antarctica . Snow affects such human activities as transportation : creating the need for keeping roadways , wings , and windows clear ; agriculture : providing water to crops and safeguarding livestock ; such sports as skiing , snowboarding , snowmachine travel ; and warfare : impairing target acquisition , degrading the performance of combatants and materiel , and impeding mobility . Snow affects ecosystems , as well , by providing an insulating layer during winter under which plants and animals are able to survive the cold . |
2630 | Jupiter | "A new storm and a new red spot on Jupiter hints at climate change, USA TODAY and dozens of other sources explained yesterday. | Jupiter Jupiter is the fifth planet from the Sun and the largest in the Solar System . It is a giant planet with a mass one-thousandth that of the Sun , but two and a half times that of all the other planets in the Solar System combined . Jupiter and Saturn are gas giants ; the other two giant planets , Uranus and Neptune are ice giants . Jupiter has been known to astronomers since antiquity . The Romans named it after their god Jupiter . When viewed from Earth , Jupiter can reach an apparent magnitude of − 2.94 , bright enough for its reflected light to cast shadows , and making it on average the third-brightest object in the night sky after the Moon and Venus . Jupiter is primarily composed of hydrogen with a quarter of its mass being helium , though helium comprises only about a tenth of the number of molecules . It may also have a rocky core of heavier elements , but like the other giant planets , Jupiter lacks a well-defined solid surface . Because of its rapid rotation , the planet 's shape is that of an oblate spheroid ( it has a slight but noticeable bulge around the equator ) . The outer atmosphere is visibly segregated into several bands at different latitudes , resulting in turbulence and storms along their interacting boundaries . A prominent result is the Great Red Spot , a giant storm that is known to have existed since at least the 17th century when it was first seen by telescope . Surrounding Jupiter is a faint planetary ring system and a powerful magnetosphere . Jupiter has at least 67 moons , including the four large Galilean moons discovered by Galileo Galilei in 1610 . Ganymede , the largest of these , has a diameter greater than that of the planet Mercury . Jupiter has been explored on several occasions by robotic spacecraft , most notably during the early Pioneer and Voyager flyby missions and later by the Galileo orbiter . In late February 2007 , Jupiter was visited by the New Horizons probe , which used Jupiter 's gravity to increase its speed and bend its trajectory en route to Pluto . The latest probe to visit the planet is Juno , which entered into orbit around Jupiter on July 4 , 2016 . Future targets for exploration in the Jupiter system include the probable ice-covered liquid ocean of its moon Europa . |
2783 | Richard_Lindzen | The study indicates far less future global warming will occur than United Nations computer models have predicted, and supports prior studies indicating increases in atmospheric carbon dioxide trap far less heat than alarmists have claimed. | Richard Lindzen Richard Siegmund Lindzen ( born February 8 , 1940 ) is an American atmospheric physicist known for his work in the dynamics of the middle atmosphere , atmospheric tides , and ozone photochemistry . He has published more than 200 scientific papers and books . From 1983 until his retirement in 2013 , he was Alfred P. Sloan Professor of Meteorology at the Massachusetts Institute of Technology . He was a lead author of Chapter 7 , `` Physical Climate Processes and Feedbacks , '' of the Intergovernmental Panel on Climate Change 's Third Assessment Report on climate change . He has criticized the scientific consensus about climate change and what he has called `` climate alarmism . '' |
830 | Solar_System | parts of the Earth will likely become close to uninhabitable | Solar System The Solar SystemCapitalization of the name varies . The International Astronomical Union , the authoritative body regarding astronomical nomenclature , specifies capitalizing the names of all individual astronomical objects , but uses mixed `` Solar System '' and `` solar system '' in their naming guidelines document . The name is commonly rendered in lower case ( `` solar system '' ) , as , for example , in the Oxford English Dictionary and Merriam-Webster 's 11th Collegiate Dictionary . is the gravitationally bound system comprising the Sun and the objects that orbit it , either directly or indirectly.The natural satellites ( moons ) orbiting the Solar System 's planets are an example of the latter . Of those objects that orbit the Sun directly , the largest eight are the planets , Historically , several other bodies were once considered planets , including , from its discovery in 1930 until 2006 , Pluto . See Former planets . with the remainder being significantly smaller objects , such as dwarf planets and small Solar System bodies . Of the objects that orbit the Sun indirectly , the moons , two are larger than the smallest planet , Mercury.The two moons larger than Mercury are Ganymede , which orbits Jupiter , and Titan , which orbits Saturn . Although bigger than Mercury , both moons have less than half the mass of Mercury . The Solar System formed 4.6 billion years ago from the gravitational collapse of a giant interstellar molecular cloud . The vast majority of the system 's mass is in the Sun , with the majority of the remaining mass contained in Jupiter . The four smaller inner planets , Mercury , Venus , Earth and Mars , are terrestrial planets , being primarily composed of rock and metal . The four outer planets are giant planets , being substantially more massive than the terrestrials . The two largest , Jupiter and Saturn , are gas giants , being composed mainly of hydrogen and helium ; the two outermost planets , Uranus and Neptune , are ice giants , being composed mostly of substances with relatively high melting points compared with hydrogen and helium , called volatiles , such as water , ammonia and methane . All planets have almost circular orbits that lie within a nearly flat disc called the ecliptic . The Solar System also contains smaller objects . The asteroid belt , which lies between the orbits of Mars and Jupiter , mostly contains objects composed , like the terrestrial planets , of rock and metal . Beyond Neptune 's orbit lie the Kuiper belt and scattered disc , which are populations of trans-Neptunian objects composed mostly of ices , and beyond them a newly discovered population of sednoids . Within these populations are several dozen to possibly tens of thousands of objects large enough that they have been rounded by their own gravity . Such objects are categorized as dwarf planets . Identified dwarf planets include the asteroid Ceres and the trans-Neptunian objects Pluto and Eris . In addition to these two regions , various other small-body populations , including comets , centaurs and interplanetary dust clouds , freely travel between regions . Six of the planets , at least four of the dwarf planets , and many of the smaller bodies are orbited by natural satellites , See List of natural satellites of the Solar System for the full list of natural satellites of the eight planets and first five dwarf planets usually termed `` moons '' after the Moon . Each of the outer planets is encircled by planetary rings of dust and other small objects . The solar wind , a stream of charged particles flowing outwards from the Sun , creates a bubble-like region in the interstellar medium known as the heliosphere . The heliopause is the point at which pressure from the solar wind is equal to the opposing pressure of the interstellar medium ; it extends out to the edge of the scattered disc . The Oort cloud , which is thought to be the source for long-period comets , may also exist at a distance roughly a thousand times further than the heliosphere . The Solar System is located in the Orion Arm , 26,000 light-years from the center of the Milky Way . |
2468 | Carbon_dioxide | "Satellite measurements indicate an absence of significant global warming since 1979, the very period that human carbon dioxide emissions have been increasing rapidly. | Carbon dioxide Carbon dioxide ( chemical formula ) is a colorless gas with a density about 60 % higher than that of air ( 1.225 g/L ) that is odorless at normally encountered concentrations . Carbon dioxide consists of a carbon atom covalently double bonded to two oxygen atoms . It occurs naturally in Earth 's atmosphere as a trace gas at a concentration of about 0.04 percent ( 400 ppm ) by volume . Natural sources include volcanoes , hot springs and geysers , and it is freed from carbonate rocks by dissolution in water and acids . Because carbon dioxide is soluble in water , it occurs naturally in groundwater , rivers and lakes , ice caps , glaciers and seawater . It is present in deposits of petroleum and natural gas . As the source of available carbon in the carbon cycle , atmospheric carbon dioxide is the primary carbon source for life on Earth and its concentration in Earth 's pre-industrial atmosphere since late in the Precambrian has been regulated by photosynthetic organisms and geological phenomena . Plants , algae and cyanobacteria use light energy to photosynthesize carbohydrate from carbon dioxide and water , with oxygen produced as a waste product . Carbon dioxide is produced by all aerobic organisms when they metabolize carbohydrates and lipids to produce energy by respiration . It is returned to water via the gills of fish and to the air via the lungs of air-breathing land animals , including humans . Carbon dioxide is produced during the processes of decay of organic materials and the fermentation of sugars in bread , beer and winemaking . It is produced by combustion of wood and other organic materials and fossil fuels such as coal , peat , petroleum and natural gas . It is a versatile industrial material , used , for example , as an inert gas in welding and fire extinguishers , as a pressurizing gas in air guns and oil recovery , as a chemical feedstock and in liquid form as a solvent in decaffeination of coffee and supercritical drying . It is added to drinking water and carbonated beverages including beer and sparkling wine to add effervescence . The frozen solid form of , known as `` dry ice '' is used as a refrigerant and as an abrasive in dry-ice blasting . Carbon dioxide is the most significant long-lived greenhouse gas in Earth 's atmosphere . Since the Industrial Revolution anthropogenic emissions - primarily from use of fossil fuels and deforestation - have rapidly increased its concentration in the atmosphere , leading to global warming . Carbon dioxide also causes ocean acidification because it dissolves in water to form carbonic acid . |
2318 | Hockey_stick_controversy | A paper by Ross McKitrick, an economics professor at the University of Guelph, and Patrick Michaels, an environmental studies professor at the University of Virginia, concludes that half of the global warming trend from 1980 to 2002 is caused by Urban Heat Island. | Hockey stick controversy In the hockey stick controversy , the data and methods used in reconstructions of the temperature record of the past 1000 years have been disputed . Reconstructions have consistently shown that the rise in the instrumental temperature record of the past 150 years is not matched in earlier centuries , and the name `` hockey stick graph '' was coined for figures showing a long-term decline followed by an abrupt rise in temperatures . These graphs were publicised to explain the scientific findings of climatology , and in addition to scientific debate over the reconstructions , they have been the topic of political dispute . The issue is part of the global warming controversy and has been one focus of political responses to reports by the Intergovernmental Panel on Climate Change ( IPCC ) . Arguments over the reconstructions have been taken up by fossil fuel industry funded lobbying groups attempting to cast doubt on climate science . The use of proxy indicators to get quantitative estimates of the temperature record of past centuries was developed from the 1990s onwards , and found indications that recent warming was exceptional . The reconstruction introduced the `` Composite Plus Scaling '' ( CPS ) method used by most later large-scale reconstructions , and its findings were disputed by Patrick Michaels at the United States House Committee on Science . In 1998 , Michael E. Mann , Raymond S. Bradley and Malcolm K. Hughes developed new statistical techniques to produce ( MBH98 ) , the first eigenvector-based climate field reconstruction ( CFR ) . This showed global patterns of annual surface temperature , and included a graph of average hemispheric temperatures back to 1400 . In ( MBH99 ) the methodology was extended back to 1000 . The term hockey stick was coined by the climatologist Jerry D. Mahlman , to describe the pattern this showed , envisaging a graph that is relatively flat to 1900 as forming an ice hockey stick 's `` shaft '' , followed by a sharp increase corresponding to the `` blade '' . A version of this graph was featured prominently in the 2001 IPCC Third Assessment Report ( TAR ) , along with four other reconstructions supporting the same conclusion . The graph was publicised , and became a focus of dispute for those opposed to the strengthening scientific consensus that late 20th-century warmth was exceptional . Those disputing the graph included Pat Michaels , the George C. Marshall Institute and Fred Singer . A paper by Willie Soon and Sallie Baliunas claiming greater medieval warmth was used by the Bush administration chief of staff Philip Cooney to justify altering the first Environmental Protection Agency Report on the Environment . The paper was quickly dismissed by scientists in the Soon and Baliunas controversy , but on July 28 , Republican Jim Inhofe spoke in the Senate citing it to claim `` that man-made global warming is the greatest hoax ever perpetrated on the American people '' . Later in 2003 , a paper by Steve McIntyre and Ross McKitrick disputing the data used in MBH98 paper was publicised by the George C. Marshall Institute and the Competitive Enterprise Institute . In 2004 , Hans von Storch published criticism of the statistical techniques as tending to underplay variations in earlier parts of the graph , though this was disputed and he later accepted that the effect was very small . In 2005 , McIntyre and McKitrick published criticisms of the principal component analysis methodology as used in MBH98 and MBH99 . The analysis therein was subsequently disputed by published papers , including and , which pointed to errors in the McIntyre and McKitrick methodology . In June 2005 , Rep. Joe Barton launched what Sherwood Boehlert , chairman of the House Science Committee , called a `` misguided and illegitimate investigation '' into the data , methods and personal information of Mann , Bradley and Hughes . At Boehlert 's request , a panel of scientists convened by the National Research Council was set up , which reported in 2006 , supporting Mann 's findings with some qualifications , including agreeing that there were some statistical failings but these had little effect on the result . Barton and U.S. Rep. Ed Whitfield requested Edward Wegman to set up a team of statisticians to investigate , and they supported McIntyre and McKitrick 's view that there were statistical failings , although they did not quantify whether there was any significant effect . They also produced an extensive network analysis which has been discredited by expert opinion and found to have issues of plagiarism . Arguments against the MBH studies were reintroduced as part of the Climatic Research Unit email controversy , but dismissed by eight independent investigations . More than two dozen reconstructions , using various statistical methods and combinations of proxy records , have supported the broad consensus shown in the original 1998 hockey-stick graph , with variations in how flat the pre-20th century `` shaft '' appears . The 2007 IPCC Fourth Assessment Report cited 14 reconstructions , 10 of which covered 1,000 years or longer , to support its strengthened conclusion that it was likely that Northern Hemisphere temperatures during the 20th century were the highest in at least the past 1,300 years . Over a dozen subsequent reconstructions , including Mann et al. 2008 and , have supported these general conclusions . |
1449 | Airliner | 43% of CO2 from commercial aviation was linked to passenger movement in narrowbody aircraft, followed by widebody jets (33%), and regional aircraft (5%). | Airliner An airliner is a type of aircraft for transporting passengers and air cargo . Such aircraft are most often operated by airlines . Although the definition of an airliner can vary from country to country , an airliner is typically defined as an aircraft intended for carrying multiple passengers or cargo in commercial service . The largest airliners are wide-body jets . These aircraft are frequently called twin-aisle aircraft because they generally have two separate aisles running from the front to the back of the passenger cabin . These aircraft are usually used for long-haul flights between airline hubs and major cities with many passengers . A smaller , more common class of airliners is the narrow-body or single aisle aircraft . These smaller airliners are generally used for short to medium-distance flights with fewer passengers than their wide-body counterparts . Regional airliners typically seat fewer than 100 passengers and may be powered by turbofans or turboprops . These airliners are the non-mainline counterparts to the larger aircraft operated by the major carriers , legacy carriers , and flag carriers and are used to feed traffic into the large airline hubs . These regional routes then form the spokes of a hub-and-spoke air transport model . The lightest ( light aircraft , list of light transport aircraft ) of short haul regional feeder airliner type aircraft that carry 19 or fewer passenger seats are called commuter aircraft , commuterliners , feederliners , and air taxis , depending on their size , engines , how they are marketed , region of the world , and seating configurations . The Beechcraft 1900 , for example , has only 19 seats . |
2012 | Emissions_trading | U.S. Sen. Ron Johnson "led the fight to let polluters release unlimited amounts of carbon pollution and took nearly $225,000 from polluters." | Emissions trading Emissions trading or cap and trade is a government-mandated , market-based approach to controlling pollution by providing economic incentives for achieving reductions in the emissions of pollutants . In contrast to command-and-control environmental regulations such as best available technology ( BAT ) standards and government subsidies , cap and trade ( CAT ) schemes are a type of flexible environmental regulation that allows organizations to decide how best to meet policy targets . Various countries , states and groups of companies have adopted such trading systems , notably for mitigating climate change . A central authority ( usually a governmental body ) allocates or sells a limited number of permits to discharge specific quantities of a specific pollutant per time period . Polluters are required to hold permits in amount equal to their emissions . Polluters that want to increase their emissions must buy permits from others willing to sell them . Financial derivatives of permits can also be traded on secondary markets . In theory , polluters who can reduce emissions most cheaply will do so , achieving the emission reduction at the lowest cost to society . Cap and trade is meant to provide the private sector with the flexibility required to reduce emissions while stimulating technological innovation and economic growth . There are active trading programs in several air pollutants . For greenhouse gases , which cause climate change , permit units are often called carbon credits . The largest greenhouse gases trading program is the European Union Emission Trading Scheme , which trades primarily in European Union Allowances ( EUAs ) ; the Californian scheme trades in California Carbon Allowances , the New Zealand scheme in New Zealand Units and the Australian scheme in Australian Units . The United States has a national market to reduce acid rain and several regional markets in nitrogen oxides . |
2104 | Greenland_ice_sheet | Greenland ice sheet won't collapse | Greenland ice sheet The Greenland ice sheet ( Grønlands indlandsis , Sermersuaq ) is a vast body of ice covering 1710000 km ² , roughly 80 % of the surface of Greenland . It is the second largest ice body in the world , after the Antarctic ice sheet . The ice sheet is almost 2400 km long in a north-south direction , and its greatest width is 1100 km at a latitude of 77 ° N , near its northern margin . The mean altitude of the ice is 2135 m . The thickness is generally more than 2 km and over 3 km at its thickest point . It is not the only ice mass of Greenland -- isolated glaciers and small ice caps cover between 76000 and around the periphery . If the entire 2850000 km3 of ice were to melt , it would lead to a global sea level rise of 7.2 m . The Greenland Ice Sheet is sometimes referred to under the term inland ice , or its Danish equivalent , indlandsis . It is also sometimes referred to as an ice cap . |
320 | Carbon_dioxide | Globally averaged thermometers show two periods of warming since 1900: a half-degree from natural causes in the first half of the 20th century, before there was an increase in industrial carbon dioxide that was enough to produce it, and another half-degree in the last quarter of the century. | Carbon dioxide Carbon dioxide ( chemical formula ) is a colorless gas with a density about 60 % higher than that of air ( 1.225 g/L ) that is odorless at normally encountered concentrations . Carbon dioxide consists of a carbon atom covalently double bonded to two oxygen atoms . It occurs naturally in Earth 's atmosphere as a trace gas at a concentration of about 0.04 percent ( 400 ppm ) by volume . Natural sources include volcanoes , hot springs and geysers , and it is freed from carbonate rocks by dissolution in water and acids . Because carbon dioxide is soluble in water , it occurs naturally in groundwater , rivers and lakes , ice caps , glaciers and seawater . It is present in deposits of petroleum and natural gas . As the source of available carbon in the carbon cycle , atmospheric carbon dioxide is the primary carbon source for life on Earth and its concentration in Earth 's pre-industrial atmosphere since late in the Precambrian has been regulated by photosynthetic organisms and geological phenomena . Plants , algae and cyanobacteria use light energy to photosynthesize carbohydrate from carbon dioxide and water , with oxygen produced as a waste product . Carbon dioxide is produced by all aerobic organisms when they metabolize carbohydrates and lipids to produce energy by respiration . It is returned to water via the gills of fish and to the air via the lungs of air-breathing land animals , including humans . Carbon dioxide is produced during the processes of decay of organic materials and the fermentation of sugars in bread , beer and winemaking . It is produced by combustion of wood and other organic materials and fossil fuels such as coal , peat , petroleum and natural gas . It is a versatile industrial material , used , for example , as an inert gas in welding and fire extinguishers , as a pressurizing gas in air guns and oil recovery , as a chemical feedstock and in liquid form as a solvent in decaffeination of coffee and supercritical drying . It is added to drinking water and carbonated beverages including beer and sparkling wine to add effervescence . The frozen solid form of , known as `` dry ice '' is used as a refrigerant and as an abrasive in dry-ice blasting . Carbon dioxide is the most significant long-lived greenhouse gas in Earth 's atmosphere . Since the Industrial Revolution anthropogenic emissions - primarily from use of fossil fuels and deforestation - have rapidly increased its concentration in the atmosphere , leading to global warming . Carbon dioxide also causes ocean acidification because it dissolves in water to form carbonic acid . |
2612 | Three_Mile_Island_accident | [T]he overwhelming majority of peer-reviewed studies [find] that CO2 in the atmosphere remained there a short time. | Three Mile Island accident The Three Mile Island accident was caused by a nuclear meltdown that occurred on March 28 , 1979 , in reactor number 2 of Three Mile Island Nuclear Generating Station ( TMI-2 ) in Dauphin County , Pennsylvania , United States . It was the most significant accident in U.S. commercial nuclear power plant history . The incident was rated a five on the seven-point International Nuclear Event Scale : Accident With Wider Consequences . The accident began with failures in the non-nuclear secondary system , followed by a stuck-open pilot-operated relief valve in the primary system , which allowed large amounts of nuclear reactor coolant to escape . The mechanical failures were compounded by the initial failure of plant operators to recognize the situation as a loss-of-coolant accident due to inadequate training and human factors , such as human-computer interaction design oversights relating to ambiguous control room indicators in the power plant 's user interface . In particular , a hidden indicator light led to an operator manually overriding the automatic emergency cooling system of the reactor because the operator mistakenly believed that there was too much coolant water present in the reactor and causing the steam pressure release . The accident crystallized anti-nuclear safety concerns among activists and the general public , resulted in new regulations for the nuclear industry , and has been cited as a contributor to the decline of a new reactor construction program that was already underway in the 1970s . The partial meltdown resulted in the release of radioactive gases and radioactive iodine into the environment . Worries were expressed by anti-nuclear movement activists ; however , epidemiological studies analyzing the rate of cancer in and around the area since the accident , determined there was a small statistically non-significant increase in the rate and thus no causal connection linking the accident with these cancers has been substantiated . Cleanup started in August 1979 , and officially ended in December 1993 , with a total cleanup cost of about $ 1 billion . |
1829 | Climate_change_in_Washington | "the cascading effects" of climate change contributed to the rise of ISIS. | Climate change in Washington Climate change in the US state of Washington is a subject of study and projection today . |
2953 | Solar_irradiance | In particular, PMOD alters the data from the Nimbus7/ERB record from 1989 to 1991. | Solar irradiance Solar irradiance is the power per unit area received from the Sun in the form of electromagnetic radiation in the wavelength range of the measuring instrument . Irradiance may be measured in space or at the Earth 's surface after atmospheric absorption and scattering . It is measured perpendicular to the incoming sunlight . Total solar irradiance ( TSI ) , is a measure of the solar power over all wavelengths per unit area incident on the Earth 's upper atmosphere . The solar constant is a conventional measure of mean TSI at a distance of one astronomical Unit ( AU ) . Irradiance is a function of distance from the Sun , the solar cycle , and cross-cycle changes . Irradiance on Earth is also measured perpendicular to the incoming sunlight . Insolation is the power received on Earth per unit area on a horizontal surface . It depends on the height of the Sun above the horizon . |
1700 | Atmospheric_methane | Methane plays a minor role in global warming but could get much worse if permafrost starts to melt. | Atmospheric methane Atmospheric methane is the methane present in Earth 's atmosphere . Atmospheric methane concentrations are of interest because it is one of the most potent greenhouse gases in Earth 's atmosphere . The 100-year global warming potential of methane is 28 . That is , over a 100-year period , it traps 28 times more heat per mass unit than carbon dioxide and 32 times the effect when accounted for aerosol interactions . Global methane levels , had risen to 1800 parts per billion ( ppb ) by 2011 , an increase by a factor of 2.5 since pre-industrial times , from 722 ppb , the highest value in at least 800,000 years . Its concentration is higher in the Northern Hemisphere since most sources ( both natural and human ) are located on land and the Northern Hemisphere has more land mass . The concentrations vary seasonally , with , for example , a minimum in the northern tropics during April − May mainly due to removal by the hydroxyl radical . Early in the Earth 's history carbon dioxide and methane likely produced a greenhouse effect . The carbon dioxide would have been produced by volcanoes and the methane by early microbes . During this time , Earth 's earliest life appeared . These first , ancient bacteria added to the methane concentration by converting hydrogen and carbon dioxide into methane and water . Oxygen did not become a major part of the atmosphere until photosynthetic organisms evolved later in Earth 's history . With no oxygen , methane stayed in the atmosphere longer and at higher concentrations than it does today . Methane is created near the surface , and it is carried into the stratosphere by rising air in the tropics . Uncontrolled build-up of methane in Earth 's atmosphere is naturally checked -- although human influence can upset this natural regulation -- by methane 's reaction with hydroxyl radicals formed from singlet oxygen atoms and with water vapor . |
765 | Scientific_consensus_on_climate_change | The broader term covers changes beyond warmer temperatures, such as shifting rainfall patterns." | Scientific consensus on climate change There is currently a strong scientific consensus that the Earth is warming and that this warming is mainly caused by human activities. This consensus is supported by various studies of scientists' opinions and by position statements of scientific organizations, many of which explicitly agree with the Intergovernmental Panel on Climate Change (IPCC) synthesis reports. Nearly all actively publishing climate scientists (97–98%) support the consensus on anthropogenic climate change, and the remaining 2% of contrarian studies either cannot be replicated or contain errors. |
637 | Mediterranean_Sea | By 2100 the seas will rise another 6 inches or so—a far cry from Al Gore's alarming numbers | Mediterranean Sea The Mediterranean Sea is a sea connected to the Atlantic Ocean , surrounded by the Mediterranean Basin and almost completely enclosed by land : on the north by Southern Europe and Anatolia , on the south by North Africa , and on the east by the Levant . The sea is sometimes considered a part of the Atlantic Ocean , although it is usually identified as a separate body of water . The name Mediterranean is derived from the Latin mediterraneus , meaning `` inland '' or `` in the middle of land '' ( from medius , `` middle '' and terra , `` land '' ) . It covers an approximate area of 2.5 million km2 ( 965,000 sq mi ) , but its connection to the Atlantic ( the Strait of Gibraltar ) is only 14 km wide . The Strait of Gibraltar is a narrow strait that connects the Atlantic Ocean to the Mediterranean Sea and separates Gibraltar and Spain in Europe from Morocco in Africa . In oceanography , it is sometimes called the Eurafrican Mediterranean Sea or the European Mediterranean Sea to distinguish it from mediterranean seas elsewhere . The Mediterranean Sea has an average depth of 1500 m and the deepest recorded point is 5267 m in the Calypso Deep in the Ionian Sea . The sea is bordered on the north by Europe , the east by Asia , and in the south by Africa . It is located between latitudes 30 ° and 46 ° N and longitudes 6 ° W and 36 ° E. Its west-east length , from the Strait of Gibraltar to the Gulf of Iskenderun , on the southwestern coast of Turkey , is approximately 4,000 km ( 2,500 miles ) . The sea 's average north-south length , from Croatia 's southern shore to Libya , is approximately 800 km ( 500 miles ) . The Mediterranean Sea , including the Sea of Marmara ( connected by the Dardanelles to the Aegean Sea ) , has a surface area of approximately 2,510,000 square km ( 970,000 square miles ) . The sea was an important route for merchants and travelers of ancient times that allowed for trade and cultural exchange between emergent peoples of the region . The history of the Mediterranean region is crucial to understanding the origins and development of many modern societies . The countries with coastlines on the Mediterranean Sea are Albania , Algeria , Bosnia and Herzegovina , Croatia , Cyprus , Egypt , France , Greece , Israel , Italy , Lebanon , Libya , Malta , Morocco , Monaco , Montenegro , Slovenia , Spain , Syria , Tunisia and Turkey . In addition , the Gaza Strip and the British Overseas Territories of Gibraltar and Akrotiri and Dhekelia have coastlines on the sea . |
1665 | Biodiversity | The effects of enhanced CO2 on terrestrial plants are variable and complex and dependent on numerous factors. | Biodiversity Biodiversity a portmanteau of `` biological diversity , '' generally refers to the variety and variability of life on Earth . According to the United Nations Environment Programme , biodiversity typically measures variation at the genetic , the species , and the ecosystem level . Terrestrial biodiversity tends to be greater near the equator , which seems to be the result of the warm climate and high primary productivity . Biodiversity is not distributed evenly on Earth , and is richest in the tropics . These tropical forest ecosystems cover less than 10 per cent of earth 's surface , and contain about 90 percent of the world 's species . Marine biodiversity tends to be highest along coasts in the Western Pacific , where sea surface temperature is highest and in the mid-latitudinal band in all oceans . There are latitudinal gradients in species diversity . Biodiversity generally tends to cluster in hotspots , and has been increasing through time , but will be likely to slow in the future . Rapid environmental changes typically cause mass extinctions . More than 99.9 percent of all species , amounting to over five billion species , that ever lived on Earth are estimated to be extinct . Estimates on the number of Earth 's current species range from 10 million to 14 million , of which about 1.2 million have been documented and over 86 percent have not yet been described . More recently , in May 2016 , scientists reported that 1 trillion species are estimated to be on Earth currently with only one-thousandth of one percent described . The total amount of related DNA base pairs on Earth is estimated at 5.0 x 1037 and weighs 50 billion tonnes . In comparison , the total mass of the biosphere has been estimated to be as much as 4 TtC ( trillion tons of carbon ) . In July 2016 , scientists reported identifying a set of 355 genes from the Last Universal Common Ancestor ( LUCA ) of all organisms living on Earth . The age of the Earth is about 4.54 billion years old . The earliest undisputed evidence of life on Earth dates at least from 3.5 billion years ago , during the Eoarchean Era after a geological crust started to solidify following the earlier molten Hadean Eon . There are microbial mat fossils found in 3.48 billion-year-old sandstone discovered in Western Australia . Other early physical evidence of a biogenic substance is graphite in 3.7 billion-year-old meta-sedimentary rocks discovered in Western Greenland . More recently , in 2015 , `` remains of biotic life '' were found in 4.1 billion-year-old rocks in Western Australia . According to one of the researchers , `` If life arose relatively quickly on Earth . . then it could be common in the universe . '' Since life began on Earth , five major mass extinctions and several minor events have led to large and sudden drops in biodiversity . The Phanerozoic eon ( the last 540 million years ) marked a rapid growth in biodiversity via the Cambrian explosion -- a period during which the majority of multicellular phyla first appeared . The next 400 million years included repeated , massive biodiversity losses classified as mass extinction events . In the Carboniferous , rainforest collapse led to a great loss of plant and animal life . The Permian -- Triassic extinction event , 251 million years ago , was the worst ; vertebrate recovery took 30 million years . The most recent , the Cretaceous -- Paleogene extinction event , occurred 65 million years ago and has often attracted more attention than others because it resulted in the extinction of the dinosaurs . The period since the emergence of humans has displayed an ongoing biodiversity reduction and an accompanying loss of genetic diversity . Named the Holocene extinction , the reduction is caused primarily by human impacts , particularly habitat destruction . Conversely , biodiversity impacts human health in a number of ways , both positively and negatively . The United Nations designated 2011 -- 2020 as the United Nations Decade on Biodiversity . |
1702 | Carbon_dioxide | CO2 levels are measured by hundreds of stations across the globe, all reporting the same trend. | Carbon dioxide Carbon dioxide ( chemical formula ) is a colorless gas with a density about 60 % higher than that of air ( 1.225 g/L ) that is odorless at normally encountered concentrations . Carbon dioxide consists of a carbon atom covalently double bonded to two oxygen atoms . It occurs naturally in Earth 's atmosphere as a trace gas at a concentration of about 0.04 percent ( 400 ppm ) by volume . Natural sources include volcanoes , hot springs and geysers , and it is freed from carbonate rocks by dissolution in water and acids . Because carbon dioxide is soluble in water , it occurs naturally in groundwater , rivers and lakes , ice caps , glaciers and seawater . It is present in deposits of petroleum and natural gas . As the source of available carbon in the carbon cycle , atmospheric carbon dioxide is the primary carbon source for life on Earth and its concentration in Earth 's pre-industrial atmosphere since late in the Precambrian has been regulated by photosynthetic organisms and geological phenomena . Plants , algae and cyanobacteria use light energy to photosynthesize carbohydrate from carbon dioxide and water , with oxygen produced as a waste product . Carbon dioxide is produced by all aerobic organisms when they metabolize carbohydrates and lipids to produce energy by respiration . It is returned to water via the gills of fish and to the air via the lungs of air-breathing land animals , including humans . Carbon dioxide is produced during the processes of decay of organic materials and the fermentation of sugars in bread , beer and winemaking . It is produced by combustion of wood and other organic materials and fossil fuels such as coal , peat , petroleum and natural gas . It is a versatile industrial material , used , for example , as an inert gas in welding and fire extinguishers , as a pressurizing gas in air guns and oil recovery , as a chemical feedstock and in liquid form as a solvent in decaffeination of coffee and supercritical drying . It is added to drinking water and carbonated beverages including beer and sparkling wine to add effervescence . The frozen solid form of , known as `` dry ice '' is used as a refrigerant and as an abrasive in dry-ice blasting . Carbon dioxide is the most significant long-lived greenhouse gas in Earth 's atmosphere . Since the Industrial Revolution anthropogenic emissions - primarily from use of fossil fuels and deforestation - have rapidly increased its concentration in the atmosphere , leading to global warming . Carbon dioxide also causes ocean acidification because it dissolves in water to form carbonic acid . |
1400 | Global_cooling | The late 1970s marked the end of a 30-year cooling trend. | Global cooling Global cooling was a conjecture during the 1970s of imminent cooling of the Earth 's surface and atmosphere culminating in a period of extensive glaciation . This hypothesis had little support in the scientific community , but gained temporary popular attention due to a combination of a slight downward trend of temperatures from the 1940s to the early 1970s and press reports that did not accurately reflect the full scope of the scientific climate literature , which showed a larger and faster-growing body of literature projecting future warming due to greenhouse gas emissions . The current scientific opinion on climate change is that the Earth has not durably cooled , but underwent global warming throughout the 20th century . |
268 | Global_warming | Some scientists believe that solar activity is more likely to influence today's climate than carbon dioxide, and Dr Soon has compiled data showing temperature in America, Canada and Mexico rises and falls in line with solar activity. | Global warming Global warming , also referred to as climate change , is the observed century-scale rise in the average temperature of the Earth 's climate system and its related effects . Multiple lines of scientific evidence show that the climate system is warming . Many of the observed changes since the 1950s are unprecedented in the instrumental temperature record which extends back to the mid 19th century , and in paleoclimate proxy records over thousands of years . In 2013 , the Intergovernmental Panel on Climate Change ( IPCC ) Fifth Assessment Report concluded that `` It is extremely likely that human influence has been the dominant cause of the observed warming since the mid-20th century . '' The largest human influence has been emission of greenhouse gases such as carbon dioxide , methane and nitrous oxide . Climate model projections summarized in the report indicated that during the 21st century the global surface temperature is likely to rise a further 0.3 to for their lowest emissions scenario and 2.6 to for the highest emissions scenario . These findings have been recognized by the national science academies of the major industrialized nations and are not disputed by any scientific body of national or international standing . Future climate change and associated impacts will differ from region to region around the globe . Anticipated effects include warming global temperature , rising sea levels , changing precipitation , and expansion of deserts in the subtropics . Warming is expected to be greater over land than over the oceans and greatest in the Arctic , with the continuing retreat of glaciers , permafrost and sea ice . Other likely changes include more frequent extreme weather events including heat waves , droughts , heavy rainfall with floods and heavy snowfall ; ocean acidification ; and species extinctions due to shifting temperature regimes . Effects significant to humans include the threat to food security from decreasing crop yields and the abandonment of populated areas due to rising sea levels . Because the climate system has a large `` inertia '' and greenhouse gases will stay in the atmosphere for a long time , many of these effects will not only exist for decades or centuries , but will persist for tens of thousands of years . Possible societal responses to global warming include mitigation by emissions reduction , adaptation to its effects , building systems resilient to its effects , and possible future climate engineering . Most countries are parties to the United Nations Framework Convention on Climate Change ( UNFCCC ) , whose ultimate objective is to prevent dangerous anthropogenic climate change . Parties to the UNFCCC have agreed that deep cuts in emissions are required and that global warming should be limited to well below 2.0 C-change relative to pre-industrial levels , with efforts made to limit warming to 1.5 C-change . Public reactions to global warming and concern about its effects are also increasing . A global 2015 Pew Research Center report showed a median of 54 % consider it `` a very serious problem '' . There are significant regional differences , with Americans and Chinese ( whose economies are responsible for the greatest annual CO2 emissions ) among the least concerned . |
903 | Carbon_dioxide | Growers regularly pump CO2 into greenhouses, raising levels to three times that of the natural environment, to produce stronger, greener, healthier plants." | Carbon dioxide Carbon dioxide ( chemical formula ) is a colorless gas with a density about 60 % higher than that of air ( 1.225 g/L ) that is odorless at normally encountered concentrations . Carbon dioxide consists of a carbon atom covalently double bonded to two oxygen atoms . It occurs naturally in Earth 's atmosphere as a trace gas at a concentration of about 0.04 percent ( 400 ppm ) by volume . Natural sources include volcanoes , hot springs and geysers , and it is freed from carbonate rocks by dissolution in water and acids . Because carbon dioxide is soluble in water , it occurs naturally in groundwater , rivers and lakes , ice caps , glaciers and seawater . It is present in deposits of petroleum and natural gas . As the source of available carbon in the carbon cycle , atmospheric carbon dioxide is the primary carbon source for life on Earth and its concentration in Earth 's pre-industrial atmosphere since late in the Precambrian has been regulated by photosynthetic organisms and geological phenomena . Plants , algae and cyanobacteria use light energy to photosynthesize carbohydrate from carbon dioxide and water , with oxygen produced as a waste product . Carbon dioxide is produced by all aerobic organisms when they metabolize carbohydrates and lipids to produce energy by respiration . It is returned to water via the gills of fish and to the air via the lungs of air-breathing land animals , including humans . Carbon dioxide is produced during the processes of decay of organic materials and the fermentation of sugars in bread , beer and winemaking . It is produced by combustion of wood and other organic materials and fossil fuels such as coal , peat , petroleum and natural gas . It is a versatile industrial material , used , for example , as an inert gas in welding and fire extinguishers , as a pressurizing gas in air guns and oil recovery , as a chemical feedstock and in liquid form as a solvent in decaffeination of coffee and supercritical drying . It is added to drinking water and carbonated beverages including beer and sparkling wine to add effervescence . The frozen solid form of , known as `` dry ice '' is used as a refrigerant and as an abrasive in dry-ice blasting . Carbon dioxide is the most significant long-lived greenhouse gas in Earth 's atmosphere . Since the Industrial Revolution anthropogenic emissions - primarily from use of fossil fuels and deforestation - have rapidly increased its concentration in the atmosphere , leading to global warming . Carbon dioxide also causes ocean acidification because it dissolves in water to form carbonic acid . |
3063 | Ozone_depletion | 'Another global warming myth comes crashing down. | Ozone depletion Ozone depletion describes two distinct but related phenomena observed since the late 1970s : a steady decline of about four percent in the total amount of ozone in Earth 's stratosphere ( the ozone layer ) , and a much larger springtime decrease in stratospheric ozone around Earth 's polar regions . The latter phenomenon is referred to as the ozone hole . In addition to these well-known stratospheric phenomena , there are also springtime polar tropospheric ozone depletion events . The details of polar ozone hole formation differ from that of mid-latitude thinning but the most important process in both is catalytic destruction of ozone by atomic halogens . The main source of these halogen atoms in the stratosphere is photodissociation of man-made halocarbon refrigerants , solvents , propellants , and foam-blowing agents ( chlorofluorocarbon ( CFCs ) , HCFCs , freons , halons ) . These compounds are transported into the stratosphere by winds after being emitted at the surface . Both types of ozone depletion were observed to increase as emissions of halocarbons increased . CFCs and other contributory substances are referred to as ozone-depleting substances ( ODS ) . Since the ozone layer prevents most harmful UVB wavelengths ( 280 -- 315 nm ) of ultraviolet light ( UV light ) from passing through the Earth 's atmosphere , observed and projected decreases in ozone generated worldwide concern , leading to adoption of the Montreal Protocol that bans the production of CFCs , halons , and other ozone-depleting chemicals such as carbon tetrachloride and trichloroethane . It is suspected that a variety of biological consequences such as increases in sunburn , skin cancer , cataracts , damage to plants , and reduction of plankton populations in the ocean 's photic zone may result from the increased UV exposure due to ozone depletion . |
1240 | North_America | "Ice-free means the central basin of the Arctic will be ice-free | North America North America is a continent entirely within the Northern Hemisphere and almost all within the Western Hemisphere . It can also be considered a northern subcontinent of the Americas . It is bordered to the north by the Arctic Ocean , to the east by the Atlantic Ocean , to the west and south by the Pacific Ocean , and to the southeast by South America and the Caribbean Sea . North America covers an area of about 24,709,000 square kilometers ( 9,540,000 square miles ) , about 16.5 % of the earth 's land area and about 4.8 % of its total surface . North America is the third largest continent by area , following Asia and Africa , and the fourth by population after Asia , Africa , and Europe . In 2013 , its population was estimated at nearly 565 million people in 23 independent states , or about 7.5 % of the world 's population , if nearby islands ( most notably the Caribbean ) are included . North America was reached by its first human populations during the last glacial period , via crossing the Bering land bridge approximately 40,000 to 17,000 years ago . The so-called Paleo-Indian period is taken to have lasted until about 10,000 years ago ( the beginning of the Archaic or Meso-Indian period ) . The Classic stage spans roughly the 6th to 13th centuries . The Pre-Columbian era ended with the transatlantic migrations and the arrival of European settlers during the Age of Discovery and the Early Modern period . Present-day cultural and ethnic patterns reflect different kind of interactions between European colonists , indigenous peoples , African slaves and their descendants . European influences are strongest in the northern parts of the continent while indigenous and African influences are relatively stronger in the south . Because of the history of colonialism , most North Americans speak English , Spanish or French and societies and states commonly reflect Western traditions . |
2047 | Carbon_dioxide | contrary to the hypothesis that rising temperature is caused by increasing CO2. | Carbon dioxide Carbon dioxide ( chemical formula ) is a colorless gas with a density about 60 % higher than that of air ( 1.225 g/L ) that is odorless at normally encountered concentrations . Carbon dioxide consists of a carbon atom covalently double bonded to two oxygen atoms . It occurs naturally in Earth 's atmosphere as a trace gas at a concentration of about 0.04 percent ( 400 ppm ) by volume . Natural sources include volcanoes , hot springs and geysers , and it is freed from carbonate rocks by dissolution in water and acids . Because carbon dioxide is soluble in water , it occurs naturally in groundwater , rivers and lakes , ice caps , glaciers and seawater . It is present in deposits of petroleum and natural gas . As the source of available carbon in the carbon cycle , atmospheric carbon dioxide is the primary carbon source for life on Earth and its concentration in Earth 's pre-industrial atmosphere since late in the Precambrian has been regulated by photosynthetic organisms and geological phenomena . Plants , algae and cyanobacteria use light energy to photosynthesize carbohydrate from carbon dioxide and water , with oxygen produced as a waste product . Carbon dioxide is produced by all aerobic organisms when they metabolize carbohydrates and lipids to produce energy by respiration . It is returned to water via the gills of fish and to the air via the lungs of air-breathing land animals , including humans . Carbon dioxide is produced during the processes of decay of organic materials and the fermentation of sugars in bread , beer and winemaking . It is produced by combustion of wood and other organic materials and fossil fuels such as coal , peat , petroleum and natural gas . It is a versatile industrial material , used , for example , as an inert gas in welding and fire extinguishers , as a pressurizing gas in air guns and oil recovery , as a chemical feedstock and in liquid form as a solvent in decaffeination of coffee and supercritical drying . It is added to drinking water and carbonated beverages including beer and sparkling wine to add effervescence . The frozen solid form of , known as `` dry ice '' is used as a refrigerant and as an abrasive in dry-ice blasting . Carbon dioxide is the most significant long-lived greenhouse gas in Earth 's atmosphere . Since the Industrial Revolution anthropogenic emissions - primarily from use of fossil fuels and deforestation - have rapidly increased its concentration in the atmosphere , leading to global warming . Carbon dioxide also causes ocean acidification because it dissolves in water to form carbonic acid . |
1531 | Scientific_consensus_on_climate_change | Earth's climate is now changing faster than at any point in the history of modern civilization, primarily as a result of human activities. | Scientific consensus on climate change There is currently a strong scientific consensus that the Earth is warming and that this warming is mainly caused by human activities. This consensus is supported by various studies of scientists' opinions and by position statements of scientific organizations, many of which explicitly agree with the Intergovernmental Panel on Climate Change (IPCC) synthesis reports. Nearly all actively publishing climate scientists (97–98%) support the consensus on anthropogenic climate change, and the remaining 2% of contrarian studies either cannot be replicated or contain errors. |
2060 | Hurricane_Sandy | Global warming is causing more hurricanes and stronger hurricanes. | Hurricane Sandy Hurricane Sandy ( unofficially referred to as `` Superstorm Sandy '' ) was the deadliest and most destructive hurricane of the 2012 Atlantic hurricane season , and the second-costliest hurricane in United States history . Classified as the eighteenth named storm , tenth hurricane and second major hurricane of the year , Sandy was a Category 3 storm at its peak intensity when it made landfall in Cuba . While it was a Category 2 storm off the coast of the Northeastern United States , the storm became the largest Atlantic hurricane on record ( as measured by diameter , with winds spanning 1100 mi ) . Estimates as of 2015 assessed damage to have been about $ 75 billion ( 2012 USD ) , a total surpassed only by Hurricane Katrina . At least 233 people were killed along the path of the storm in eight countries . Sandy developed from a tropical wave in the western Caribbean Sea on October 22 , quickly strengthened , and was upgraded to Tropical Storm Sandy six hours later . Sandy moved slowly northward toward the Greater Antilles and gradually intensified . On October 24 , Sandy became a hurricane , made landfall near Kingston , Jamaica , re-emerged a few hours later into the Caribbean Sea and strengthened into a Category 2 hurricane . On October 25 , Sandy hit Cuba as a Category 3 hurricane , then weakened to a Category 1 hurricane . Early on October 26 , Sandy moved through the Bahamas . On October 27 , Sandy briefly weakened to a tropical storm and then restrengthened to a Category 1 hurricane . Early on October 29 , Sandy curved west-northwest ( the `` left turn '' or `` left hook '' ) and then moved ashore near Brigantine , New Jersey , just to the northeast of Atlantic City , as a post-tropical cyclone with hurricane-force winds . In Jamaica , winds left 70 % of residents without electricity , blew roofs off buildings , killed one , and caused about $ 100 million ( 2012 USD ) in damage . Sandy 's outer bands brought flooding to Haiti , killing at least 54 , causing food shortages , and leaving about 200,000 homeless ; the hurricane also caused two deaths in the Dominican Republic . In Puerto Rico , one man was swept away by a swollen river . In Cuba , there was extensive coastal flooding and wind damage inland , destroying some 15,000 homes , killing 11 , and causing $ 2 billion ( 2012 USD ) in damage . Sandy caused two deaths and damage estimated at $ 700 million ( 2012 USD ) in The Bahamas . In the United States , Hurricane Sandy affected 24 states , including the entire eastern seaboard from Florida to Maine and west across the Appalachian Mountains to Michigan and Wisconsin , with particularly severe damage in New Jersey and New York . Its storm surge hit New York City on October 29 , flooding streets , tunnels and subway lines and cutting power in and around the city . Damage in the United States amounted to $ 71.4 billion ( 2013 USD ) . In Canada , two were killed in Ontario and an estimated $ 100 million ( 2012 CAD ) in damage was caused throughout Ontario and Quebec . |
1614 | Sea_ice | Arctic sea ice extent was lower in the past. | Sea ice Sea ice arises as seawater freezes . Because ice is less dense than water , it floats on the ocean 's surface ( as does fresh water ice , which has an even lower density ) . Sea ice covers about 7 % of the Earth 's surface and about 12 % of the world 's oceans . Much of the world 's sea ice is enclosed within the polar ice packs in the Earth 's polar regions : the Arctic ice pack of the Arctic Ocean and the Antarctic ice pack of the Southern Ocean . Polar packs undergo a significant yearly cycling in surface extent , a natural process upon which depends the Arctic ecology , including the ocean 's ecosystems . Due to the action of winds , currents and temperature fluctuations , sea ice is very dynamic , leading to a wide variety of ice types and features . Sea ice may be contrasted with icebergs , which are chunks of ice shelves or glaciers that calve into the ocean . Depending on location , sea ice expanses may also incorporate icebergs . |
348 | Atlantic_hurricane | There's no trend in hurricane-related flooding in the U.S. | Atlantic hurricane An Atlantic hurricane or tropical storm is a tropical cyclone that forms in the Atlantic Ocean , usually in the summer or fall . A hurricane differs from a cyclone or typhoon only on the basis of location . A hurricane is a storm that occurs in the Atlantic Ocean and northeastern Pacific Ocean , a typhoon occurs in the northwestern Pacific Ocean , and a cyclone occurs in the south Pacific or Indian Ocean . Tropical cyclones can be categorized by intensity . Tropical storms have one-minute maximum sustained winds of at least 39 mph ( 34 knots , 17 m/s , 63 km/h ) , while hurricanes have one-minute maximum sustained winds exceeding 74 mph ( 64 knots , 33 m/s , 119 km/h ) . Most North Atlantic tropical storms and hurricanes form between June 1 and November 30 . The United States National Hurricane Center monitors the basin and issues reports , watches , and warnings about tropical weather systems for the North Atlantic Basin as one of the Regional Specialized Meteorological Centers for tropical cyclones , as defined by the World Meteorological Organization . In recent times , tropical disturbances that reach tropical storm intensity are named from a predetermined list . Hurricanes that result in significant damage or casualties may have their names retired from the list at the request of the affected nations in order to prevent confusion should a subsequent storm be given the same name . On average , in the North Atlantic basin ( from 1966 to 2009 ) 11.3 named storms occur each season , with an average of 6.2 becoming hurricanes and 2.3 becoming major hurricanes ( Category 3 or greater ) . The climatological peak of activity is around September 11 each season . In March 2004 , Catarina was the first hurricane-intensity tropical cyclone ever recorded in the Southern Atlantic Ocean . Since 2011 , the Brazilian Navy Hydrographic Center has started to use the same scale of the North Atlantic Ocean for tropical cyclones in the South Atlantic Ocean and assign names to those which reach 35 kn . |
916 | Retreat_of_glaciers_since_1850 | The acceleration is making some scientists fear that Antarctica's ice sheet may have entered the early stages of an unstoppable disintegration. | Retreat of glaciers since 1850 The retreat of glaciers since 1850 affects the availability of fresh water for irrigation and domestic use , mountain recreation , animals and plants that depend on glacier-melt , and , in the longer term , the level of the oceans . Studied by glaciologists , the temporal coincidence of glacier retreat with the measured increase of atmospheric greenhouse gases is often cited as an evidentiary underpinning of global warming . Mid-latitude mountain ranges such as the Himalayas , Alps , Rocky Mountains , Cascade Range , and the southern Andes , as well as isolated tropical summits such as Mount Kilimanjaro in Africa , are showing some of the largest proportionate glacial losses . Glacier mass balance is the key determinant of the health of a glacier . If the amount of frozen precipitation in the accumulation zone exceeds the quantity of glacial ice lost due to melting or in the ablation zone a glacier will advance ; if the accumulation is less than the ablation , the glacier will retreat . Glaciers in retreat will have negative mass balances , and if they do not find an equilibrium between accumulation and ablation , will eventually disappear . The Little Ice Age was a period from about 1550 to 1850 when the world experienced relatively cooler temperatures compared to the present . Subsequently , until about 1940 , glaciers around the world retreated as the climate warmed substantially . Glacial retreat slowed and even reversed temporarily , in many cases , between 1950 and 1980 as global temperatures cooled slightly . Since 1980 , a significant global warming has led to glacier retreat becoming increasingly rapid and ubiquitous , so much so that some glaciers have disappeared altogether , and the existences of many of the remaining glaciers are threatened . In locations such as the Andes of South America and Himalayas in Asia , the demise of glaciers in these regions has the potential to affect water supplies in those areas . The retreat of mountain glaciers , notably in western North America , Asia , the Alps and tropical and subtropical regions of South America , Africa and Indonesia , provide evidence for the rise in global temperatures since the late 19th century . The acceleration of the rate of retreat since 1995 of key outlet glaciers of the Greenland and West Antarctic ice sheets may foreshadow a rise in sea level , which would affect coastal regions . |
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