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2189	Air_pollution	This makes it clear that this time around humans are the cause, mainly by our CO2 emissions.	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 .
2530	Physical_impacts_of_climate_change	Glaciers are in rapid retreat worldwide, despite 1 error in 1 paragraph in a 3000 page IPCC report.	Physical impacts of climate change This article is about the physical impacts of climate change . For some of these physical impacts , their effect on social and economic systems are also described . This article refers to reports produced by the IPCC . In their usage , `` climate change '' refers to a change in the state of the climate that can be identified by changes in the mean and/or variability of its properties , and that persists for extended periods , typically decades or longer ( IPCC , 2007d :30 ) . The climate change referred to may be due to natural causes and/or the result of human activity .
496	Natural_disaster	Nine years into that 11-year hurricane drought, a NASA scientist computed it as a 1-in-177-year event.	Natural disaster A natural disaster is a major adverse event resulting from natural processes of the Earth ; examples include floods , hurricanes , tornadoes , volcanic eruptions , earthquakes , tsunamis , and other geologic processes . A natural disaster can cause loss of life or property damage , and typically leaves some economic damage in its wake , the severity of which depends on the affected population 's resilience , or ability to recover and also on the infrastructure available . An adverse event will not rise to the level of a disaster if it occurs in an area without vulnerable population . In a vulnerable area , however , such as Nepal during the 2015 earthquake , an earthquake can have disastrous consequences and leave lasting damage , requiring years to repair .
3111	Hockey_stick_controversy	Ljungqvist's millennial temperature reconstruction was very similar to Moberg et al.	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 .
261	Soon_and_Baliunas_controversy	in 1995 one scientist at the IPCC – Jonathan Overpeck – wrote an email to a colleague claiming 'we have to get rid of the Medieval Warm Period.'	Soon and Baliunas controversy The Soon and Baliunas controversy involved the publication in 2003 of a review study written by aerospace engineer Willie Soon and astronomer Sallie Baliunas in the journal Climate Research , which was quickly taken up by the G.W. Bush administration as a basis for amending the first Environmental Protection Agency Report on the Environment . The paper was strongly criticized by numerous scientists for its methodology and for its misuse of data from previously published studies , prompting concerns about the peer review process of the paper . The controversy resulted in the resignation of half of the editors of the journal and in the admission by its publisher Otto Kinne that the paper should not have been published as it was .
1882	Gainesville,_Florida	Every four minutes, another American home or business goes solar.	Gainesville, Florida Gainesville is the county seat and largest city in Alachua County , Florida , United States , and the principal city of the Gainesville , Florida Metropolitan Statistical Area ( MSA ) . The population of Gainesville in the 2013 US Census estimates was 127,488 , a 2.4 % growth from 2010 . Gainesville is the largest city in the region of North Central Florida . It is also a component of the Gainesville-Lake City Combined Statistical Area , which had a 2013 population of 337,925 . Gainesville is home to the University of Florida , the nation 's ninth-largest university campus by enrollment , as well as to Santa Fe College . The Gainesville MSA was ranked as the No. 1 place to live in North America in the 2007 edition of Cities Ranked and Rated . Also in 2007 , Gainesville was ranked as one of the `` best places to live and play '' in the United States by National Geographic Adventure . Gainesville was ranked as the `` 5th meanest city '' in the United States by the National Coalition for the Homeless twice , first in 2004 for its criminalization of homelessness and then in 2009 for its ordinance restricting soup kitchens to 130 meals a day.Meanwhile , the 130-meal restriction has since been repealed .
1772	Global_warming	Preventing global warming is relatively cheap; business-as-usual will cause accelerating climate damage costs that economists struggle to even estimate.	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 .
2378	Stern_Review	The costs of inaction far outweigh the costs of mitigation.	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 ) .
2837	Tendency_of_the_rate_of_profit_to_fall	In fact, the rate of increase from September onward is the fastest rate of change on record, either upwards or downwards.	Tendency of the rate of profit to fall The tendency of the rate of profit to fall ( TRPF ) is a hypothesis in economics and political economy , most famously expounded by Karl Marx in chapter 13 of Capital , Volume III . Although not accepted in 20th century mainstream economics , the existence of such a tendency was widely accepted in the 19th century . Economists as diverse as Adam Smith , John Stuart Mill , David Ricardo and Stanley Jevons referred explicitly to the TRPF as an empirical phenomenon . They differed in their explanation about why the TRPF might occur . In his 1857 Grundrisse manuscript , Karl Marx called the tendency of the rate of profit to fall `` the most important law of political economy '' and sought to give a causal explanation for it , in terms of his theory of capital accumulation . The tendency is already foreshadowed in chapter 25 of Capital , Volume I ( on the `` general law of capital accumulation '' ) , but in Part 3 of the draft manuscript of Marx 's Capital , Volume III , edited posthumously for publication by Friedrich Engels , an extensive analysis is provided of the tendency . Marx regarded the TRPF as proof that capitalist production could not be an everlasting form of production , since , in the end , the profit principle itself would suffer a breakdown . However , because Marx never published any finished manuscript on the TRPF himself , because the tendency is hard to prove or disprove theoretically , and because it is hard to test and measure the rate of profit , Marx 's TRPF theory has been a topic of controversy for more than a century .
1867	Water_pollution	Connie Mack "is protecting Chevron oil from a multi-billion dollar lawsuit over pollution of rivers and rainforests."	Water pollution Water pollution is the contamination of water bodies ( e.g. lakes , rivers , oceans , aquifers and groundwater ) . This form of environmental degradation occurs when pollutants are directly or indirectly discharged into water bodies without adequate treatment to remove harmful compounds . Water pollution affects the entire biosphere -- plants and organisms living in these bodies of water . In almost all cases the effect is damaging not only to individual species and population , but also to the natural biological communities .
768	History_of_the_world	"We've known about [the greenhouse effect] for more than a century.	History of the world The history of the world ( or world history ) describes the history of humanity ( or human history ) as determined by the study of archaeological and written records , beginning with the invention of writing . The roots of civilization reach back to the earliest introduction of primitive technology and culture , while Prehistory begins in the Palaeolithic Era , or `` Early Stone Age '' , which is followed by the Neolithic Era , or `` New Stone Age '' , and the Agricultural Revolution ( between 8000 and 5000 BCE ) in the Fertile Crescent . The latter period marked a change in human history , as humans began the systematic husbandry of plants and animals . Agriculture advanced , and most humans transitioned from a nomadic to a settled lifestyle as farmers in permanent settlements . Nomadism continued in some locations , especially in isolated regions with few domesticable plant species , but the relative security and increased productivity provided by farming allowed human communities to expand into increasingly larger units , fostered by advances in transportation . As farming developed , grain agriculture became more sophisticated and prompted a division of labour to store food between growing seasons . Labour divisions then led to the rise of a leisured upper class and the development of cities . The growing complexity of human societies necessitated systems of writing and accounting . Many cities developed on the banks of lakes and rivers as early as 3000 BCE , when some of the first prominent , well-developed settlements had arisen in Mesopotamia ( `` the Land between the Rivers '' ) , on the banks of Egypt 's Nile River , in the Indus River valley , and along the rivers of China . The history of the Old World ( particularly Europe and the Mediterranean ) is commonly divided into ancient history ( or `` Antiquity '' ) , up to 476 CE ; post-classical history ( or `` the Middle Ages '' ) , from the 5th through 15th centuries , including the rise of Christianity , the Islamic Golden Age ( c. 750 CE -- c. 1258 CE ) and the early Italian Renaissance ( beginning around 1300 CE ) ; the early modern period , from the 15th century to the late 18th , including the Age of Enlightenment ; and the late modern period , from the Industrial Revolution to the present , including contemporary history . In the mid-15th century , the invention of modern printing , employing movable type , revolutionized communication , helping end the Middle Ages and ushering in the Scientific Revolution . By the 18th century , the accumulation of knowledge and technology , especially in Europe , had reached a critical mass that brought about the Industrial Revolution . Outside the Old World , including ancient China and ancient India , historical timelines unfolded differently . However , by the 18th century , due to extensive world trade and colonization , the histories of most civilizations had become substantially intertwined ( see `` Globalization '' ) . In the last quarter-millennium , the rates of growth of population , knowledge , technology , communications , commerce , weapons destructiveness and environmental degradation have greatly accelerated , creating opportunities and perils that now confront the planet 's human communities .
712	Lake_Tahoe	"Instead of a three-foot increase in ocean levels by the end of the century, six feet was more likely, according to DeConto and Pollard's findings.	Lake Tahoe Lake Tahoe ( -LSB- ˈtɑːhoʊ -RSB- ) is a large freshwater lake in the Sierra Nevada of the United States . Lying at 6225 ft , it straddles the border between California and Nevada , west of Carson City . Lake Tahoe is the largest alpine lake in North America , and at 122160280 acre.ft trails only the five Great Lakes as the largest by volume in the United States . Its depth is 1645 ft , making it the second deepest in the United States after Crater Lake in Oregon ( 1945 ft ) . The lake was formed about 2 million years ago as part of the Lake Tahoe Basin , with the modern extent being shaped during the ice ages . It is known for the clarity of its water and the panorama of surrounding mountains on all sides . The area surrounding the lake is also referred to as Lake Tahoe , or simply Tahoe . More than 75 % of the lake 's watershed is national forest land , comprising the Lake Tahoe Basin Management Unit of the United States Forest Service . Lake Tahoe is a major tourist attraction in both Nevada and California . It is home to winter sports , summer outdoor recreation , and scenery enjoyed throughout the year . Snow and ski resorts are a significant part of the area 's economy and reputation . The Nevada side also offers large casinos , with highways providing year-round access to the entire area .
1715	Global_warming	Theory, models and direct measurement confirm CO2 is currently the main driver of climate change.	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 .
196	Carbon_dioxide	Without carbon dioxide, all life on Earth would die	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 .
1829	Isis	"the cascading effects" of climate change contributed to the rise of ISIS.	Isis Isis ( -LSB- ˈaɪsɪs -RSB- Ἶσις -LSB- îː.sis -RSB- ; original Egyptian pronunciation more likely `` Aset '' or `` Iset '' ) is a goddess from the polytheistic pantheon of Egypt . She was first worshiped in ancient Egyptian religion , and later her worship spread throughout the Roman Empire and the greater Greco-Roman world . Isis is still widely worshiped by many pagans today in diverse religious contexts ; including a number of distinct pagan religions , the modern Goddess movement , and interfaith organizations such as the Fellowship of Isis . Isis was worshipped as the ideal mother and wife as well as the patroness of nature and magic . She was the friend of slaves , sinners , artisans and the downtrodden , but she also listened to the prayers of the wealthy , maidens , aristocrats and rulers . Isis is often depicted as the mother of Horus , the falcon-headed deity associated with king and kingship ( although in some traditions Horus 's mother was Hathor ) . Isis is also known as protector of the dead and goddess of children . The name Isis means `` Throne '' . Her headdress is a throne . As the personification of the throne , she was an important representation of the pharaoh 's power . The pharaoh was depicted as her child , who sat on the throne she provided . Her cult was popular throughout Egypt , but her most important temples were at Behbeit El Hagar in the Nile delta , and , beginning in the reign with Nectanebo I ( 380 -- 362 BCE ) , on the island of Philae in Upper Egypt . In the typical form of her myth , Isis was the first daughter of Geb , god of the Earth , and Nut , goddess of the Sky , and she was born on the fourth intercalary day . She married her brother , Osiris , and she conceived Horus with him . Isis was instrumental in the resurrection of Osiris when he was murdered by Set . Using her magical skills , she restored his body to life after having gathered the body parts that had been strewn about the earth by Set . This myth became very important during the Greco-Roman period . For example , it was believed that the Nile River flooded every year because of the tears of sorrow which Isis wept for Osiris . Osiris 's death and rebirth was relived each year through rituals . The worship of Isis eventually spread throughout the Greco-Roman world , continuing until the suppression of paganism in the Christian era . The popular motif of Isis suckling her son Horus , however , lived on in a Christianized context as the popular image of Mary suckling her infant son Jesus from the fifth century onward .
1067	Durban	"In an old climate, … extremely warm years were less common and snowpack was more reliable …	Durban Durban ( eThekwini , from itheku meaning `` bay/lagoon '' ) is the largest city in the South African province of KwaZulu-Natal . Durban 's metropolitan municipality ranks third among the most populous urban areas in South Africa after Johannesburg and Cape Town . It is also the second most important manufacturing hub in South Africa after Johannesburg . It forms part of the eThekwini Metropolitan Municipality . Durban is famous for being the busiest port in South Africa . It is also seen as one of the major centres of tourism because of the city 's warm subtropical climate and extensive beaches . The municipality , which includes neighbouring towns , has a population of almost 3.5 million , making the combined municipality one of the biggest cities on the Indian Ocean coast of the African continent . It is the largest city in KwaZulu-Natal which is the 2nd most populous province in South Africa . It has the highest number of dollar millionaires added per year of any South African city with the number rising 200 per cent between 2000 and 2014 . In May 2015 , Durban was officially recognised as one of the New7Wonders Cities together with Vigan , Doha , La Paz , Havana , Beirut , and Kuala Lumpur .
1665	Climate_change_and_agriculture	The effects of enhanced CO2 on terrestrial plants are variable and complex and dependent on numerous factors.	Climate change and agriculture -RSB- Climate change and agriculture are interrelated processes , both of which take place on a global scale . Climate change affects agriculture in a number of ways , including through changes in average temperatures , rainfall , and climate extremes ( e.g. , heat waves ) ; changes in pests and diseases ; changes in atmospheric carbon dioxide and ground-level ozone concentrations ; changes in the nutritional quality of some foods ; and changes in sea level . Climate change is already affecting agriculture , with effects unevenly distributed across the world . Future climate change will likely negatively affect crop production in low latitude countries , while effects in northern latitudes may be positive or negative . Climate change will probably increase the risk of food insecurity for some vulnerable groups , such as the poor . Agriculture contributes to climate change by ( 1 ) anthropogenic emissions of greenhouse gases ( GHGs ) , and ( 2 ) by the conversion of non-agricultural land ( e.g. , forests ) into agricultural land . Agriculture , forestry and land-use change contributed around 20 to 25 % to global annual emissions in 2010 . There are a range of policies that can reduce the risk of negative climate change impacts on agriculture , and to reduce GHG emissions from the agriculture sector .
2553	Percentage	The climate debate is, in reality, about a 1.6 watts per square metre or 0.5 per cent discrepancy in the poorly known planetary energy balance."	Percentage In mathematics , a percentage is a number or ratio expressed as a fraction of 100 . It is often denoted using the percent sign , '' % '' , or the abbreviations `` pct . '' , `` pct '' ; sometimes the abbreviation `` pc '' is also used . A percentage is a dimensionless number ( pure number ) .
2011	Emissions_trading	U.S. Pays $1 Billion into Green Climate Fund, Top Polluters Pay Nothing	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 .
2460	Tundra	That drop in temperature came after what was described in the National Geographic as 'six decades of abnormal warmth'."	Tundra In physical geography , tundra is a type of biome where the tree growth is hindered by low temperatures and short growing seasons . The term tundra comes through Russian тундра ( tûndra ) from the Kildin Sami word tūndâr `` uplands '' , `` treeless mountain tract '' . There are three types of tundra : Arctic tundra , alpine tundra , and Antarctic tundra . In tundra , the vegetation is composed of dwarf shrubs , sedges and grasses , mosses , and lichens . Scattered trees grow in some tundra regions . The ecotone ( or ecological boundary region ) between the tundra and the forest is known as the tree line or timberline .
2574	Coral_reef	On a world scale coral reefs are in decline.	Coral reef Coral reefs are diverse underwater ecosystems held together by calcium carbonate structures secreted by corals . Coral reefs are built by colonies of tiny animals found in marine waters that contain few nutrients . Most coral reefs are built from stony corals , which in turn consist of polyps that cluster in groups . The polyps belong to a group of animals known as Cnidaria , which also includes sea anemones and jellyfish . Unlike sea anemones , corals secrete hard carbonate exoskeletons which support and protect the coral polyps . Most reefs grow best in warm , shallow , clear , sunny and agitated waters . Often called `` rainforests of the sea '' , shallow coral reefs form some of the most diverse ecosystems on Earth . They occupy less than 0.1 % of the world 's ocean surface , about half the area of France , yet they provide a home for at least 25 % of all marine species , including fish , mollusks , worms , crustaceans , echinoderms , sponges , tunicates and other cnidarians . Paradoxically , coral reefs flourish even though they are surrounded by ocean waters that provide few nutrients . They are most commonly found at shallow depths in tropical waters , but deep water and cold water corals also exist on smaller scales in other areas . Coral reefs deliver ecosystem services to tourism , fisheries and shoreline protection . The annual global economic value of coral reefs is estimated between US$ 29.8-375 billion . However , coral reefs are fragile ecosystems , partly because they are very sensitive to water temperature . They are under threat from climate change , oceanic acidification , blast fishing , cyanide fishing for aquarium fish , sunscreen use , overuse of reef resources , and harmful land-use practices , including urban and agricultural runoff and water pollution , which can harm reefs by encouraging excess algal growth .
1445	Greenhouse_gas_emissions_by_the_United_States	CO2 emissions from all commercial operations in 2018 totaled 918 million metric tons—2.4% of global CO2 emissions from fossil fuel use.	Greenhouse gas emissions by the United States According to the U.S. Environmental Protection Agency ( EPA ) , the United States produced 6,587 million metric tonnes of carbon-dioxide equivalent greenhouse gas ( GHG ) emissions in 2015 . Compared to 2014 levels , U.S. greenhouse gas emissions decreased in 2015 . Compared to levels in 1990 , emissions have increased by about 4 percent . From year to year , emissions can rise and fall due to changes in the economy , the price of fuel , and other factors . The EPA has attributed recent decreases to a reduction in emissions from fossil fuel combustion , which was a result of multiple factors including substitution from coal to natural gas consumption in the electric power sector ; warmer winter conditions that reduced demand for heating fuel in the residential and commercial sectors ; and a slight decrease in electricity demand . While the Bush administration opted against Kyoto-type policies to reduce emissions , the Obama administration and various state , local , and regional governments have attempted to adopt some Kyoto Protocol goals on a local basis . For example , the Regional Greenhouse Gas Initiative ( RGGI ) founded in January 2007 is a state-level emissions capping and trading program by nine northeastern U.S. states . In December 2009 President Obama set a target for reducing U.S. greenhouse gas ( GHG ) emissions in the range of 17 % below 2005 levels by 2020 . The U.S. State Department offered a nation-level perspective in the Fourth US Climate Action Report ( USCAR ) to the United Nations Framework Convention on Climate Change , including measures to address climate change . The report showed that the country was on track to achieve President Bush 's goal of reducing greenhouse gas emissions per unit of gross domestic product ) by 18 percent from 2002 to 2012 . Over that same period , actual GHG emissions were projected to increase by 11 percent . The report estimated that in 2006 , U.S. GHG emissions decreased 1.5 percent from 2005 to 7,075.6 million tonnes of carbon dioxide equivalent . This was an increase of 15.1 percent from the 1990 levels of 6,146.7 million tonnes ( or 0.9 percent annual increase ) , and an increase of 1.4 percent from the 2000 levels of 6,978.4 million tonnes . By 2012 GHG emissions were projected to increase to more than 7,709 million tonnes of carbon dioxide equivalent , which would be 26 percent above 1990 levels .
1783	Global_warming_hiatus	Internal variability can only account for small amounts of warming and cooling over periods of decades, and scientific studies have consistently shown that it cannot account for the global warming over the past century.	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 .
1155	Sea_level_rise	But observations, such as those on our CO2 Coalition website, show that increased CO2 levels over the next century will cause modest and beneficial warming—perhaps as much as one degree Celsius (1.8 degrees Fahrenheit)	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 .
338	Scientific_consensus_on_climate_change	Rapid assessment of average temperatures in France between 26-28 June showed a "substantial" increase in the likelihood of the heatwave happening as a result of human-caused global warming, experts at the World Weather Attribution group said.	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.
2924	Ice_core	The long-term correlation between CO2 and temperature is well established.	Ice core An ice core is a core sample that is typically removed from an ice sheet , most commonly from the polar ice caps of Antarctica , Greenland or from high mountain glaciers elsewhere . As the ice forms from the incremental buildup of annual layers of snow , lower layers are older than upper , and an ice core contains ice formed over a range of years . The properties of the ice and the recrystallized inclusions within the ice can then be used to reconstruct a climatic record over the age range of the core , normally through isotopic analysis . This enables the reconstruction of local temperature records and the history of atmospheric composition . Ice cores contain an abundance of information about climate . Inclusions in the snow of each year remain in the ice , such as wind-blown dust , ash , pollen , bubbles of atmospheric gas and radioactive substances . The variety of climatic proxies is greater than in any other natural recorder of climate , such as tree rings or sediment layers . These include ( proxies for ) temperature , ocean volume , precipitation , chemistry and gas composition of the lower atmosphere , volcanic eruptions , solar variability , sea-surface productivity , desert extent and forest fires . The length of the record depends on the depth of the ice core and varies from a few years up to 800 kyr ( 800,000 years ) for the EPICA core . The time resolution ( i.e. the shortest time period which can be accurately distinguished ) depends on the amount of annual snowfall , and reduces with depth as the ice compacts under the weight of layers accumulating on top of it . Upper layers of ice in a core correspond to a single year or sometimes a single season . Deeper into the ice the layers thin and annual layers become indistinguishable . An ice core from the right site can be used to reconstruct an uninterrupted and detailed climate record extending over hundreds of thousands of years , providing information on a wide variety of aspects of climate at each point in time . It is the simultaneity of these properties recorded in the ice that makes ice cores such a powerful tool in paleoclimate research .
2200	Climate_change_denial	The Petition Project features over 31,000 scientists signing the petition stating "There is no convincing scientific evidence that human release of carbon dioxide will, in the forseeable future, cause catastrophic heating of the Earth's atmosphere ...".	Climate change denial Climate change denial , or global warming denial , is part of the global warming controversy . It involves denial , dismissal , unwarranted doubt or contrarian views which strongly depart from the scientific opinion on climate change , including the extent to which it is caused by humans , its impacts on nature and human society , or the potential of adaptation to global warming by human actions . Some deniers do endorse the term , but others often prefer the term climate change skepticism , although this is a misnomer for those who deny anthropogenic global warming . In effect , the two terms form a continuous , overlapping range of views , and generally have the same characteristics : both reject , to a greater or lesser extent , mainstream scientific opinion on climate change . Climate change denial can also be implicit , when individuals or social groups accept the science but fail to come to terms with it or to translate their acceptance into action . Several social science studies have analyzed these positions as forms of denialism . Campaigning to undermine public trust in climate science has been described as a `` denial machine '' of industrial , political and ideological interests , supported by conservative media and skeptical bloggers in manufacturing uncertainty about global warming . In the public debate , phrases such as climate skepticism have frequently been used with the same meaning as climate denialism . The labels are contested : those actively challenging climate science commonly describe themselves as `` skeptics '' , but many do not comply with common standards of scientific skepticism and , regardless of evidence , persistently deny the validity of human caused global warming . Although scientific opinion on climate change is that human activity is extremely likely to be the primary driver of climate change , the politics of global warming have been affected by climate change denial , hindering efforts to prevent climate change and adapt to the warming climate . Those promoting denial commonly use rhetorical tactics to give the appearance of a scientific controversy where there is none . Of the world 's countries , the climate change denial industry is most powerful in the United States . Since January 2015 , the United States Senate Committee on Environment and Public Works has been chaired by oil lobbyist and climate change denier Jim Inhofe . Inhofe is notorious for having called climate change `` the greatest hoax ever perpetrated against the American people '' and for having claimed to have debunked the alleged hoax in February 2015 when he brought a snowball with him in the Senate chamber and tossed it across the floor . Organised campaigning to undermine public trust in climate science is associated with conservative economic policies and backed by industrial interests opposed to the regulation of emissions . Climate change denial has been associated with the fossil fuels lobby , the Koch brothers , industry advocates and libertarian think tanks , often in the United States . More than 90 % of papers sceptical on climate change originate from right-wing think tanks . The total annual income of these climate change counter-movement-organizations is roughly $ 900 million . Between 2002 and 2010 , nearly $ 120 million ( # 77 million ) was anonymously donated via the Donors Trust and Donors Capital Fund to more than 100 organisations seeking to undermine the public perception of the science on climate change . In 2013 the Center for Media and Democracy reported that the State Policy Network ( SPN ) , an umbrella group of 64 U.S. think tanks , had been lobbying on behalf of major corporations and conservative donors to oppose climate change regulation . Since the late 1970s , oil companies have published research broadly in line with the standard views on global warming . Despite this , oil companies organized a climate change denial campaign to disseminate public disinformation for several decades , a strategy that has been compared to the organized denial of the hazards of tobacco smoking by tobacco companies .
2588	Carbon_dioxide	However, satellite and surface measurements observe an enhanced greenhouse effect at the wavelengths that CO2 absorb energy.	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 .
443	Greenhouse_gas	"Today climate scientists are obsessed with the level of carbon dioxide in the atmosphere, a very very small part of the overall picture.	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 .
621	Snow	Dr. Gutzler said spring temperatures have an impact, too, with warmer air causing more snow to turn to vapor and essentially disappear.	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 .
1776	Climate_change_denial	If anyone claims to be part of the 97 percent, it means they disagree with the contrarian argument that humans are having a minimal impact on global warming.	Climate change denial Climate change denial , or global warming denial , is part of the global warming controversy . It involves denial , dismissal , unwarranted doubt or contrarian views which strongly depart from the scientific opinion on climate change , including the extent to which it is caused by humans , its impacts on nature and human society , or the potential of adaptation to global warming by human actions . Some deniers do endorse the term , but others often prefer the term climate change skepticism , although this is a misnomer for those who deny anthropogenic global warming . In effect , the two terms form a continuous , overlapping range of views , and generally have the same characteristics : both reject , to a greater or lesser extent , mainstream scientific opinion on climate change . Climate change denial can also be implicit , when individuals or social groups accept the science but fail to come to terms with it or to translate their acceptance into action . Several social science studies have analyzed these positions as forms of denialism . Campaigning to undermine public trust in climate science has been described as a `` denial machine '' of industrial , political and ideological interests , supported by conservative media and skeptical bloggers in manufacturing uncertainty about global warming . In the public debate , phrases such as climate skepticism have frequently been used with the same meaning as climate denialism . The labels are contested : those actively challenging climate science commonly describe themselves as `` skeptics '' , but many do not comply with common standards of scientific skepticism and , regardless of evidence , persistently deny the validity of human caused global warming . Although scientific opinion on climate change is that human activity is extremely likely to be the primary driver of climate change , the politics of global warming have been affected by climate change denial , hindering efforts to prevent climate change and adapt to the warming climate . Those promoting denial commonly use rhetorical tactics to give the appearance of a scientific controversy where there is none . Of the world 's countries , the climate change denial industry is most powerful in the United States . Since January 2015 , the United States Senate Committee on Environment and Public Works has been chaired by oil lobbyist and climate change denier Jim Inhofe . Inhofe is notorious for having called climate change `` the greatest hoax ever perpetrated against the American people '' and for having claimed to have debunked the alleged hoax in February 2015 when he brought a snowball with him in the Senate chamber and tossed it across the floor . Organised campaigning to undermine public trust in climate science is associated with conservative economic policies and backed by industrial interests opposed to the regulation of emissions . Climate change denial has been associated with the fossil fuels lobby , the Koch brothers , industry advocates and libertarian think tanks , often in the United States . More than 90 % of papers sceptical on climate change originate from right-wing think tanks . The total annual income of these climate change counter-movement-organizations is roughly $ 900 million . Between 2002 and 2010 , nearly $ 120 million ( # 77 million ) was anonymously donated via the Donors Trust and Donors Capital Fund to more than 100 organisations seeking to undermine the public perception of the science on climate change . In 2013 the Center for Media and Democracy reported that the State Policy Network ( SPN ) , an umbrella group of 64 U.S. think tanks , had been lobbying on behalf of major corporations and conservative donors to oppose climate change regulation . Since the late 1970s , oil companies have published research broadly in line with the standard views on global warming . Despite this , oil companies organized a climate change denial campaign to disseminate public disinformation for several decades , a strategy that has been compared to the organized denial of the hazards of tobacco smoking by tobacco companies .
939	Global_warming	"Recent computer forecasts suggest that if greenhouse gas emissions continue at a high level, parts of Antarctica could break up rapidly, causing the ocean to rise six feet or more by the end of this century.	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 .
474	Climate_change_in_the_Arctic	Sea ice continued its declining trend, both in the Arctic and Antarctic.	Climate change in the Arctic The effects of global warming in the Arctic , or climate change in the Arctic include rising temperatures , loss of sea ice , and melting of the Greenland ice sheet with a related cold temperature anomaly , observed in recent years . Potential methane release from the region , especially through the thawing of permafrost and methane clathrates , is also a concern . The Arctic warms twice as fast compared to the rest of the world . The pronounced warming signal , the amplified response of the Arctic to global warming , it is often seen as a leading indicator of global warming . The melting of Greenland 's ice sheet is linked to polar amplification . According to a study published in 2016 , about 0.5 ◦ C of the warming in the Arctic has been attributed to reductions in sulfate aerosols in Europe since 1980 .
10	Carbon_dioxide_in_Earth's_atmosphere	Human additions of CO2 are in the margin of error of current measurements and the gradual increase in CO2 is mainly from oceans degassing as the planet slowly emerges from the last ice age.	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 .
2132	Climatic_Research_Unit_email_controversy	Freedom of Information (FOI) requests were ignored	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 .
2907	Sea_ice	Maximum warming occurs over the surface during winter while less surface warming is found in summer when heat is being used to melt sea ice.	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 .
972	Sperm_whale	"Arctic land stores about twice as much carbon as the atmosphere.	Sperm whale The sperm whale ( Physeter macrocephalus ) , or cachalot , is the largest of the toothed whales and the largest toothed predator . It is the only living member of genus Physeter , and one of three extant species in the sperm whale family , along with the pygmy sperm whale and dwarf sperm whale of the genus Kogia . The sperm whale is a pelagic mammal with a worldwide range , and will migrate seasonally for feeding and breeding . Females and young males live together in groups while mature males live solitary lives outside of the mating season . The females cooperate to protect and nurse their young . Females give birth every four to twenty years , and care for the calves for more than a decade . A mature sperm whale has few natural predators , although calves and weakened adults are sometimes killed by pods of orcas . Mature males average 16 m in length but some may reach 20.5 m , with the head representing up to one-third of the animal 's length . Plunging to 2250 m , it is the second deepest diving mammal , following only the Cuvier 's beaked whale . The sperm whale is a prominent user of echolocation and communication , with vocalization as loud as 230 decibels ( re 1 µPa at 1 m ) underwater . It has the largest brain of any animal on Earth , more than five times heavier than a human 's . Sperm whales can live for more than 60 years . The spermaceti oil from which the whale derives its name was a prime target of the whaling industry , and was dominant for use in oil lamps , lubricants , and candles . Ambergris is a solid waxy waste product from its digestive system . It is still highly valued as a fixative in perfumes and other uses . It remains as flotsam from deceased whales , and is sought by beachcombers . The species is now protected by a whaling moratorium , and is currently listed as vulnerable by the International Union for the Conservation of Nature and Natural Resources ( IUCN ) .
2587	Carbon_dioxide_in_Earth's_atmosphere	If the CO2 effect was saturated, adding more CO2 should add no additional greenhouse effect.	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 .
1510	Climate_change_feedback	Doubling the concentration of atmospheric CO2 from its pre-industrial level, in the absence of other forcings and feedbacks, would likely cause a warming of ~0.3°C to 1.1°C.	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 . ''
261	Temperature_record_of_the_past_1000_years	in 1995 one scientist at the IPCC – Jonathan Overpeck – wrote an email to a colleague claiming 'we have to get rid of the Medieval Warm Period.'	Temperature record of the past 1000 years For information on the description of the Medieval Warm Period and Little Ice Age in various IPCC reports see MWP and LIA in IPCC reportsThe temperature record of the past 1,000 years is reconstructed using data from climate proxy records in conjunction with the modern instrumental temperature record which only covers the last 150 years at a global scale . Large-scale reconstructions covering part or all of the 1st millennium and 2nd millennium have shown that recent temperatures are exceptional : the Intergovernmental Panel on Climate Change Fourth Assessment Report of 2007 concluded that `` Average Northern Hemisphere temperatures during the second half of the 20th century were very likely higher than during any other 50-year period in the last 500 years and likely '' the highest in at least the past 1,300 years . '' The curve shown in graphs of these reconstructions is widely known as the hockey stick graph because of the sharp increase in temperatures during the last century . As of 2010 this broad pattern was supported by more than two dozen reconstructions , using various statistical methods and combinations of proxy records , with variations in how flat the pre-20th-century `` shaft '' appears . Sparseness of proxy records results in considerable uncertainty for earlier periods . Individual proxy records , such as tree ring widths and densities used in dendroclimatology , are calibrated against the instrumental record for the period of overlap . Networks of such records are used to reconstruct past temperatures for regions : tree ring proxies have been used to reconstruct Northern Hemisphere extratropical temperatures ( within the tropics trees do not form rings ) but are confined to land areas and are scarce in the Southern Hemisphere which is largely ocean . Wider coverage is provided by multiproxy reconstructions , incorporating proxies such as lake sediments , ice cores and corals which are found in different regions , and using statistical methods to relate these sparser proxies to the greater numbers of tree ring records . The `` Composite Plus Scaling '' ( CPS ) method is widely used for large-scale multiproxy reconstructions of hemispheric or global average temperatures ; this is complemented by Climate Field Reconstruction ( CFR ) methods which show how climate patterns have developed over large spatial areas , making the reconstruction useful for investigating natural variability and long-term oscillations as well as for comparisons with patterns produced by climate models . During the 1,900 years before the 20th century , it is likely that the next warmest period was from 950 to 1100 , with peaks at different times in different regions . This has been called the Medieval Warm Period , and some evidence suggests widespread cooler conditions during a period around the 17th century known as the Little Ice Age . In the hockey stick controversy , contrarians have asserted that the Medieval Warm Period was warmer than at present , and have disputed the data and methods of climate reconstructions .
2840	Sea_level_rise	Arctic sea ice is also falling at an accelerated rate.	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 .
1383	Richard_Tol	a new study by a leading climate economist, Richard Tol of the University of Sussex, concludes that warming may well bring gains, because carbon dioxide causes crops and wild ecosystems to grow greener and more drought-resistant.	Richard Tol Richard S. J. Tol ( born 2 December 1969 , Hoorn , the Netherlands ) is a professor of economics at the University of Sussex . He is also professor of the economics of climate change at the Vrije Universiteit Amsterdam . He is a member of the Academia Europaea .
1871	Donald_Trump	Donald Trump "thinks that climate change is a hoax, invented by the Chinese."	Donald Trump Donald John Trump ( born June 14 , 1946 ) is the 45th and current President of the United States . Before entering politics , he was a businessman and television personality . Trump was born and raised in Queens , New York City , and earned an economics degree from the Wharton School . He then took charge of The Trump Organization , the real estate and construction firm founded by his paternal grandmother , which he ran for 45 years until 2016 . During his real estate career , Trump built , renovated , and managed numerous office towers , hotels , casinos , and golf courses . Besides real estate , he started several side ventures and has licensed the use of his name for the branding of various products and properties , including Trump Entertainment Resorts , Trump Steaks , and Trump Vodka . He was the founder of Trump University . He owned the Miss USA and Miss Universe pageants from 1996 to 2015 , and he produced and hosted The Apprentice , a reality television series on NBC , from 2004 to 2015 . His net worth was estimated to be $ 3.5 billion , making him the 544th richest person in the world . Trump first publicly expressed interest in running for political office in 1987 . He won two Reform Party presidential primaries in 2000 , but withdrew his candidacy early on . In June 2015 , he launched his campaign for the 2016 presidential election and quickly emerged as the front-runner among seventeen candidates in the Republican primaries . His remaining opponents all suspended their campaigns by the end of May 2016 , and in July he was formally nominated at the Republican National Convention along with Indiana governor Mike Pence as his running mate . Many of his campaign statements were controversial or false , generating much free media coverage . Trump won the general election on November 8 , 2016 , in a surprise victory against Democratic opponent Hillary Clinton and commenced his presidency on January 20 , 2017 . He became the oldest and wealthiest person ever to assume the presidency , the first without prior military or government service , and the fifth to have won the election while losing the popular vote . His political positions have been described by scholars and commentators as populist , protectionist , and nationalist .
1609	Greenland_ice_sheet	Greenland has only lost a tiny fraction of its ice mass.	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 .
2042	Natural_gas	Recent research also indicates that the quantity of fossil fuels staying in the atmosphere is much less than previously thought.	Natural gas Natural gas is a naturally occurring hydrocarbon gas mixture consisting primarily of methane , but commonly including varying amounts of other higher alkanes , and sometimes a small percentage of carbon dioxide , nitrogen , hydrogen sulfide , or helium . It is formed when layers of decomposing plant and animal matter are exposed to intense heat and pressure under the surface of the Earth over millions of years . The energy that the plants originally obtained from the sun is stored in the form of chemical bonds in the gas . Natural gas is a fossil fuel used as a source of energy for heating , cooking , and electricity generation . It is also used as fuel for vehicles and as a chemical feedstock in the manufacture of plastics and other commercially important organic chemicals . Fossil fuel based natural gas is a non-renewable resource . Natural gas is found in deep underground rock formations or associated with other hydrocarbon reservoirs in coal beds and as methane clathrates . Petroleum is another resource and fossil fuel found in close proximity to and with natural gas . Most natural gas was created over time by two mechanisms : biogenic and thermogenic . Biogenic gas is created by methanogenic organisms in marshes , bogs , landfills , and shallow sediments . Deeper in the earth , at greater temperature and pressure , thermogenic gas is created from buried organic material . In petroleum production gas is often burnt as flare gas . The World Bank estimates that over 150 cubic kilometers of natural gas are flared or vented annually . Before natural gas can be used as a fuel , most , but not all , must be processed to remove impurities , including water , to meet the specifications of marketable natural gas . The by-products of this processing include : ethane , propane , butanes , pentanes , and higher molecular weight hydrocarbons , hydrogen sulfide ( which may be converted into pure sulfur ) , carbon dioxide , water vapor , and sometimes helium and nitrogen . Natural gas is often informally referred to simply as `` gas '' , especially when compared to other energy sources such as oil or coal . However , it is not to be confused with gasoline , especially in North America , where the term gasoline is often shortened in colloquial usage to gas . Natural gas was used by the Chinese in about 500 BCE ( possibly even 1000 BCE ) . They discovered a way to transport gas seeping from the ground in crude pipelines of bamboo to where it was used to boil salt water to extract the salt , in the Ziliujing District of Sichuan . The world 's first industrial extraction of natural gas started at Fredonia , New York , United States in 1825 . By 2009 , 66 000 km ³ ( or 8 % ) had been used out of the total 850 000 km ³ of estimated remaining recoverable reserves of natural gas . Based on an estimated 2015 world consumption rate of about 3400 km ³ of gas per year , the total estimated remaining economically recoverable reserves of natural gas would last 250 years at current consumption rates . An annual increase in usage of 2 -- 3 % could result in currently recoverable reserves lasting significantly less , perhaps as few as 80 to 100 years .
2561	James_Hansen	Observed sea levels are actually tracking at the upper range of the IPCC projections.	James Hansen James Edward Hansen ( born 29 March 1941 ) is an American adjunct professor in the Department of Earth and Environmental Sciences at Columbia University . He is best known for his research in climatology , his 1988 Congressional testimony on climate change that helped raise broad awareness of global warming , and his advocacy of action to avoid dangerous climate change . In recent years he has become a climate activist to mitigate the effects of climate change , on a few occasions leading to his arrest . In 2000 , Hansen advanced an alternative view of global warming over the last 100 years , arguing that during that time frame the negative forcing via aerosols and the positive forcing via largely balanced each other out , and that the 0.74 ± 0.18 ° C net rise in average global temperatures could mostly be explained by greenhouse gases other than carbon dioxide , such as methane and chlorofluorocarbons . However , even then he wrote `` the future balance of forcings is likely to shift toward dominance of CO2 over aerosols ''
104	Gaia_hypothesis	Increases in atmospheric CO2 followed increases in temperature.	Gaia hypothesis The Gaia hypothesis ( -LSB- ˈɡaɪ.ə -RSB- , -LSB- ˈɡeɪ.ə -RSB- ) , also known as the Gaia theory or the Gaia principle , proposes that organisms interact with their inorganic surroundings on Earth to form a synergistic self-regulating , complex system that helps to maintain and perpetuate the conditions for life on the planet . Topics of interest include how the biosphere and the evolution of life forms affect the stability of global temperature , ocean salinity , oxygen in the atmosphere , the maintenance of a hydrosphere of liquid water and other environmental variables that affect the habitability of Earth . The hypothesis was formulated by the chemist James Lovelock and co-developed by the microbiologist Lynn Margulis in the 1970s . The hypothesis was initially criticized for being teleological , and contradicting principles of natural selection , but later refinements aligned the Gaia hypothesis with ideas from fields such as Earth system science , biogeochemistry and systems ecology , with Lovelock referring to the `` geophysiology '' of the Earth . Even so , the Gaia hypothesis continues to attract criticism , and today some scientists consider it to be only weakly supported by , or at odds with , the available evidence . In 2006 , the Geological Society of London awarded Lovelock the Wollaston Medal in part for his work on the Gaia hypothesis .
1541	Sea_level_rise	Sea level rise due to global warming is exaggerated.	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 .
2308	Effects_of_global_warming	"The 30 major droughts of the 20th century were likely natural in all respects; and, hence, they are "indicative of what could also happen in the future," as Narisma	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 .
978	Effects_of_global_warming	The extreme cycles of dry and wet weather appear to have been intensifying over the last three decades.	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 .
962	Sea	In April the extent of Arctic sea ice was back to where it was in April 13 years ago	Sea A sea is a large body of salt water that is surrounded in whole or in part by land . More broadly , `` the sea '' is the interconnected system of Earth 's salty , oceanic waters -- considered as one global ocean or as several principal oceanic divisions . The sea moderates Earth 's climate and has important roles in the water cycle , carbon cycle , and nitrogen cycle . Although the sea has been traveled and explored since prehistory , the modern scientific study of the sea -- oceanography -- dates broadly to the British Challenger expedition of the 1870s . The sea is conventionally divided into up to five large oceanic sections -- including the International Hydrographic Organization 's four named oceans ( the Atlantic , Pacific , Indian , and Arctic ) and the Southern Ocean ; smaller , second-order sections , such as the Mediterranean , are known as seas . Owing to the present state of continental drift , the Northern Hemisphere is now fairly equally divided between land and sea ( a ratio of about 2:3 ) but the South is overwhelmingly oceanic ( 1:4.7 ) . Salinity in the open ocean is generally in a narrow band around 3.5 % by mass , although this can vary in more landlocked waters , near the mouths of large rivers , or at great depths . About 85 % of the solids in the open sea are sodium chloride . Deep-sea currents are produced by differences in salinity and temperature . Surface currents are formed by the friction of waves produced by the wind and by tides , the changes in local sea level produced by the gravity of the Moon and Sun . The direction of all of these is governed by surface and submarine land masses and by the rotation of the Earth ( the Coriolis effect ) . Former changes in sea levels have left continental shelves , shallow areas in the sea close to land . These nutrient-rich waters teem with life , which provide humans with substantial supplies of food -- mainly fish , but also shellfish , mammals , and seaweed -- which are both harvested in the wild and farmed . The most diverse areas surround great tropical coral reefs . Whaling in the deep sea was once common but whales ' dwindling numbers prompted international conservation efforts and finally a moratorium on most commercial hunting . Oceanography has established that not all life is restricted to the sunlit surface waters : even under enormous depths and pressures , nutrients streaming from hydrothermal vents support their own unique ecosystem . Life may have started there and aquatic microbial mats are generally credited with the oxygenation of Earth 's atmosphere ; both plants and animals first evolved in the sea . The sea is an essential aspect of human trade , travel , mineral extraction , and power generation . This has also made it essential to warfare and left major cities exposed to earthquakes and volcanoes from nearby faults ; powerful tsunami waves ; and hurricanes , typhoons , and cyclones produced in the tropics . This importance and duality has affected human culture , from early sea gods to the epic poetry of Homer to the changes induced by the Columbian Exchange , from burial at sea to Basho 's haikus to hyperrealist marine art , and inspiring music ranging from the shanties in The Complaynt of Scotland to Rimsky-Korsakov 's `` The Sea and Sinbad 's Ship '' to A-mei 's `` Listen to the Sea '' . It is the scene of leisure activities including swimming , diving , surfing , and sailing . However , population growth , industrialization , and intensive farming have all contributed to present-day marine pollution . Atmospheric carbon dioxide is being absorbed in increasing amounts , lowering its pH in a process known as ocean acidification . The shared nature of the sea has made overfishing an increasing problem .
316	General_circulation_model	the models predicted seven times as much warming as has been observed	General circulation model A general circulation model ( GCM ) is a type of climate model . It employs a mathematical model of the general circulation of a planetary atmosphere or ocean . It uses the Navier -- Stokes equations on a rotating sphere with thermodynamic terms for various energy sources ( radiation , latent heat ) . These equations are the basis for computer programs used to simulate the Earth 's atmosphere or oceans . Atmospheric and oceanic GCMs ( AGCM and OGCM ) are key components along with sea ice and land-surface components . GCMs and global climate models are used for weather forecasting , understanding the climate and forecasting climate change . Versions designed for decade to century time scale climate applications were originally created by Syukuro Manabe and Kirk Bryan at the Geophysical Fluid Dynamics Laboratory in Princeton , New Jersey . These models are based on the integration of a variety of fluid dynamical , chemical and sometimes biological equations .
51	Scientific_consensus_on_climate_change	CO2 does not cause climate change, it RESPONDS to it [...]	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.
2119	Iris_hypothesis	Lindzen and Choi find low climate sensitivity	Iris hypothesis The iris hypothesis is a hypothesis proposed by Richard Lindzen et al. in 2001 that suggested increased sea surface temperature in the tropics would result in reduced cirrus clouds and thus more infrared radiation leakage from Earth 's atmosphere . His study of observed changes in cloud coverage and modeled effects on infrared radiation released to space as a result supported the hypothesis . This suggested infrared radiation leakage was hypothesized to be a negative feedback in which an initial warming would result in an overall cooling of the surface . The consensus view is that increased sea surface temperature would result in increased cirrus clouds and reduced infrared radiation leakage and therefore a positive feedback . Other scientists subsequently tested the hypothesis . Some concluded that there was no evidence supporting the hypothesis . Others found evidence suggesting that increased sea surface temperature in the tropics did indeed reduce cirrus clouds but found that the effect was nonetheless a positive feedback rather than the negative feedback that Lindzen had hypothesized . A later 2007 study conducted by Roy Spencer et al. using updated satellite data potentially supported the iris hypothesis . In 2011 , Lindzen published a rebuttal to the main criticisms . In 2015 a paper was published which again suggested the possibility of an `` Iris Effect '' . It also proposed what it called a `` plausible physical mechanism for an iris effect . ''
2417	Triton_(moon)	Mars, Triton, Pluto and Jupiter all show global warming, pointing to the Sun as the dominating influence in determining climate throughout the solar system."	Triton (moon) Triton is the largest natural satellite of the planet Neptune . It was discovered on October 10 , 1846 , by English astronomer William Lassell . It is the only large moon in the Solar System with a retrograde orbit , an orbit in the opposite direction to its planet 's rotation . At 2700 km in diameter , it is the seventh-largest moon in the Solar System . Because of its retrograde orbit and composition similar to Pluto 's , Triton is thought to have been a dwarf planet captured from the Kuiper belt . Triton has a surface of mostly frozen nitrogen , a mostly water-ice crust , an icy mantle and a substantial core of rock and metal . The core makes up two-thirds of its total mass . Triton has a mean density of 2.061 g/cm3 and is composed of approximately 15 -- 35 % water ice . Triton is one of the few moons in the Solar System known to be geologically active ( the others being Jupiter 's Io and Saturn 's Enceladus ) . As a consequence , its surface is relatively young with sparse impact craters , and a complex geological history revealed in intricate cryovolcanic and tectonic terrains . Part of its surface has geysers erupting sublimated nitrogen gas , contributing to a tenuous nitrogen atmosphere less than 1/70 ,000 the pressure of Earth 's atmosphere at sea level .
109	Sea	Local and regional sea levels continue to exhibit typical natural variability—in some places rising and in others falling.	Sea A sea is a large body of salt water that is surrounded in whole or in part by land . More broadly , `` the sea '' is the interconnected system of Earth 's salty , oceanic waters -- considered as one global ocean or as several principal oceanic divisions . The sea moderates Earth 's climate and has important roles in the water cycle , carbon cycle , and nitrogen cycle . Although the sea has been traveled and explored since prehistory , the modern scientific study of the sea -- oceanography -- dates broadly to the British Challenger expedition of the 1870s . The sea is conventionally divided into up to five large oceanic sections -- including the International Hydrographic Organization 's four named oceans ( the Atlantic , Pacific , Indian , and Arctic ) and the Southern Ocean ; smaller , second-order sections , such as the Mediterranean , are known as seas . Owing to the present state of continental drift , the Northern Hemisphere is now fairly equally divided between land and sea ( a ratio of about 2:3 ) but the South is overwhelmingly oceanic ( 1:4.7 ) . Salinity in the open ocean is generally in a narrow band around 3.5 % by mass , although this can vary in more landlocked waters , near the mouths of large rivers , or at great depths . About 85 % of the solids in the open sea are sodium chloride . Deep-sea currents are produced by differences in salinity and temperature . Surface currents are formed by the friction of waves produced by the wind and by tides , the changes in local sea level produced by the gravity of the Moon and Sun . The direction of all of these is governed by surface and submarine land masses and by the rotation of the Earth ( the Coriolis effect ) . Former changes in sea levels have left continental shelves , shallow areas in the sea close to land . These nutrient-rich waters teem with life , which provide humans with substantial supplies of food -- mainly fish , but also shellfish , mammals , and seaweed -- which are both harvested in the wild and farmed . The most diverse areas surround great tropical coral reefs . Whaling in the deep sea was once common but whales ' dwindling numbers prompted international conservation efforts and finally a moratorium on most commercial hunting . Oceanography has established that not all life is restricted to the sunlit surface waters : even under enormous depths and pressures , nutrients streaming from hydrothermal vents support their own unique ecosystem . Life may have started there and aquatic microbial mats are generally credited with the oxygenation of Earth 's atmosphere ; both plants and animals first evolved in the sea . The sea is an essential aspect of human trade , travel , mineral extraction , and power generation . This has also made it essential to warfare and left major cities exposed to earthquakes and volcanoes from nearby faults ; powerful tsunami waves ; and hurricanes , typhoons , and cyclones produced in the tropics . This importance and duality has affected human culture , from early sea gods to the epic poetry of Homer to the changes induced by the Columbian Exchange , from burial at sea to Basho 's haikus to hyperrealist marine art , and inspiring music ranging from the shanties in The Complaynt of Scotland to Rimsky-Korsakov 's `` The Sea and Sinbad 's Ship '' to A-mei 's `` Listen to the Sea '' . It is the scene of leisure activities including swimming , diving , surfing , and sailing . However , population growth , industrialization , and intensive farming have all contributed to present-day marine pollution . Atmospheric carbon dioxide is being absorbed in increasing amounts , lowering its pH in a process known as ocean acidification . The shared nature of the sea has made overfishing an increasing problem .
3064	Greenland_ice_sheet	No warming since at least 1995, no melting glaciers and now no rising sea levels.	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 .
2751	Climate_change_mitigation	The argument that solving the global warming problem by reducing human greenhouse gas emissions is "too hard" generally stems from the belief that (i) our technology is not sufficiently advanced to achieve significant emissions reductions,	Climate change mitigation Climate change mitigation consists of actions to limit the magnitude or rate of long-term climate change . Climate change mitigation generally involves reductions in human ( anthropogenic ) emissions of greenhouse gases ( GHGs ) . Mitigation may also be achieved by increasing the capacity of carbon sinks , e.g. , through reforestation . Mitigation policies can substantially reduce the risks associated with human-induced global warming . According to the IPCC 's 2014 assessment report , `` Mitigation is a public good ; climate change is a case of the ` tragedy of the commons . Effective climate change mitigation will not be achieved if each agent ( individual , institution or country ) acts independently in its own selfish interest ( see international cooperation and emissions trading ) , suggesting the need for collective action . Some adaptation actions , on the other hand , have characteristics of a private good as benefits of actions may accrue more directly to the individuals , regions , or countries that undertake them , at least in the short term . Nevertheless , financing such adaptive activities remains an issue , particularly for poor individuals and countries . '' Examples of mitigation include phasing out fossil fuels by switching to low-carbon energy sources , such as renewable and nuclear energy , and expanding forests and other `` sinks '' to remove greater amounts of carbon dioxide from the atmosphere . Energy efficiency may also play a role , for example , through improving the insulation of buildings . Another approach to climate change mitigation is climate engineering . Most countries are parties to the United Nations Framework Convention on Climate Change ( UNFCCC ) . The ultimate objective of the UNFCCC is to stabilize atmospheric concentrations of GHGs at a level that would prevent dangerous human interference of the climate system . Scientific analysis can provide information on the impacts of climate change , but deciding which impacts are dangerous requires value judgments . In 2010 , Parties to the UNFCCC agreed that future global warming should be limited to below 2.0 ° C ( 3.6 ° F ) relative to the pre-industrial level . With the Paris Agreement of 2015 this was confirmed , but was revised with a new target laying down `` parties will do the best '' to achieve warming below 1.5 ° C . The current trajectory of global greenhouse gas emissions does not appear to be consistent with limiting global warming to below 1.5 or 2 ° C . Other mitigation policies have been proposed , some of which are more stringent or modest than the 2 ° C limit .
2420	Quaternary_glaciation	The sun has shown no long term trend since 1950 and in fact has shown a slight cooling trend in recent decades.	Quaternary glaciation The Quaternary glaciation , also known as the Pleistocene glaciation or the current ice age , is a series of glacial events separated by interglacial events during the Quaternary period from 2.58 Ma ( million years ago ) to present . During this period , ice sheets expanded , notably from out of Antarctica and Greenland , and fluctuating ice sheets occurred elsewhere ( for example , the Laurentide ice sheet ) . The major effects of the ice age are erosion and deposition of material over large parts of the continents , modification of river systems , creation of millions of lakes , changes in sea level , development of pluvial lakes far from the ice margins , isostatic adjustment of the crust , and abnormal winds . It affected oceans , flooding , and biological communities . The ice sheets themselves , by raising the albedo , affect a major feedback on climate cooling .
79	IPCC_Fourth_Assessment_Report	The rate of warming according to the data is much slower than the models used by the IPCC	IPCC Fourth Assessment Report Climate Change 2007 , the Fourth Assessment Report ( AR4 ) of the United Nations Intergovernmental Panel on Climate Change ( IPCC ) , is the fourth in a series of reports intended to assess scientific , technical and socio-economic information concerning climate change , its potential effects , and options for adaptation and mitigation . The report is the largest and most detailed summary of the climate change situation ever undertaken , produced by thousands of authors , editors , and reviewers from dozens of countries , citing over 6,000 peer-reviewed scientific studies . It supersedes the Third Assessment Report ( 2001 ) , and is superseded by the Fifth Assessment Report . The headline findings of the report were : `` warming of the climate system is unequivocal '' , and `` most of the observed increase in global average temperatures since the mid-20th century is very likely due to the observed increase in anthropogenic greenhouse gas concentrations . ''
1465	Human_impact_on_marine_life	Since the beginning of the Industrial Revolution, the acidity of surface ocean waters has increased by about 30 percent.13,14	Human impact on marine life Human activities affect marine life and marine habitats through overfishing, habitat loss, the introduction of invasive species, ocean pollution, ocean acidification and ocean warming. These impact marine ecosystems and food webs and may result in consequences as yet unrecognised for the biodiversity and continuation of marine life forms.According to the IPCC (2019), since 1950 "many marine species across various groups have undergone shifts in geographical range and seasonal activities in response to ocean warming, sea ice change and biogeochemical changes, such as oxygen loss, to their habitats."It has been estimated only 13% of the ocean area remains as wilderness, mostly in open ocean areas rather than along the coast.
3032	Carbon_dioxide_in_Earth's_atmosphere	Consequently, CO2 levels at around 1,000 to 2,300 ppm were actually low enough to promote glaciation in the southern continent of Gondwana.	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 .
2679	Carbon_dioxide	"The solubility of carbon dioxide in water is listed in the Handbook of Chemistry and Physics as a declining function of temperature. ...	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 .
1050	December	In Albany, New York, the high temperature of 74 degrees on Thursday was the warmest temperature on record for any day during the months of December, January and February.	December December is the twelfth and final month of the year in the Julian and Gregorian Calendars . It is the seventh and last month to have the length of 31 days . December got its name from the Latin word decem ( meaning ten ) because it was originally the tenth month of the year in the Roman calendar , which began in March . The winter days following December were not included as part of any month . Later , the months of January and February were created out of the monthless period and added to the beginning of the calendar , but December retained its name . In Ancient Rome , one of the four Agonalia , this day in honor of Sol Indiges was held on December 11 , as was Septimontium . Dies Natalis was held on of the temple of Tellus on December 13 , Consualia was held on December 15 , Saturnalia was held December 17 -- 23 , Opiconsivia held on December 19 , Divalia on December 21 , Larentalia on December 23 , and the Dies Natalis of Sol Invictus was held on December 25 . These dates do not correspond to the modern Gregorian calendar . The Anglo-Saxons referred to December/January as Ġēolamonaþ ( modern English : `` Yule month '' ) . The French Republican Calendar contained December within the months of Frimaire and Nivôse .
1662	Earth	Other parts of the earth got colder when Greenland got warmer.	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 .
199	James_Lovelock	In the past, warming has never been a threat to life on Earth.	James Lovelock James Ephraim Lovelock ( born 26 July 1919 ) is an independent scientist , environmentalist and futurist who lives in Devon , England . He is best known for proposing the Gaia hypothesis , which postulates that the Earth functions as a self-regulating system .
806	Cold_wave	Days of near-100-degree-Fahrenheit temperatures cooked the Mountain West in early July, and a scorching heat wave lingered over the Pacific Northwest in early August."	Cold wave A cold wave ( known in some regions as a cold snap ) is a weather phenomenon that is distinguished by a cooling of the air . Specifically , as used by the U.S. National Weather Service , a cold wave is a rapid fall in temperature within a 24-hour period requiring substantially increased protection to agriculture , industry , commerce , and social activities . The precise criterion for a cold wave is determined by the rate at which the temperature falls , and the minimum to which it falls . This minimum temperature is dependent on the geographical region and time of year . In the United States , a cold spell is defined as the national average high temperature dropping below 20 F.
1551	Captain_America:_The_First_Avenger	We're coming out of the Little Ice Age.	Captain America: The First Avenger Captain America : The First Avenger is a 2011 American superhero film based on the Marvel Comics character Captain America , produced by Marvel Studios and distributed by Paramount Pictures . It is the fifth film in the Marvel Cinematic Universe . The film was directed by Joe Johnston , written by Christopher Markus & Stephen McFeely , and stars Chris Evans , Tommy Lee Jones , Hugo Weaving , Hayley Atwell , Sebastian Stan , Dominic Cooper , Neal McDonough , Derek Luke , and Stanley Tucci . Set predominantly during World War II , Captain America : The First Avenger tells the story of Steve Rogers , a sickly man from Brooklyn who is transformed into super-soldier Captain America and must stop the Red Skull , who intends to use an artifact called the `` Tesseract '' as an energy-source for world domination . Captain America : The First Avenger began as a concept in 1997 and was scheduled for distribution by Artisan Entertainment . However , a lawsuit , not settled until September 2003 , disrupted the project . In 2005 , Marvel Studios received a loan from Merrill Lynch , and planned to finance and release it through Paramount Pictures . Directors Jon Favreau and Louis Leterrier were interested in directing the project before Johnston was approached in 2008 . The principal characters were cast between March and June 2010 . Production of Captain America : The First Avenger began in June 2010 , and filming took place in London , Manchester , Caerwent , and Liverpool in the United Kingdom , and Los Angeles in the United States . The film was converted to 3D in post-production . Captain America : The First Avenger premiered in Hollywood on July 19 , 2011 , and was released in the United States on July 22 , 2011 . The film received positive reviews and was commercially successful , grossing over $ 370 million worldwide . The Blu-ray and DVD were released on October 25 , 2011 . A sequel titled Captain America : The Winter Soldier was released on April 4 , 2014 , and a third film titled Captain America : Civil War was released on May 6 , 2016 .
1622	Global_warming	Postma disproved the greenhouse effect.	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 .
1644	Water_scarcity	Most glaciers are retreating, posing a serious problem for millions who rely on glaciers for water.	Water scarcity Water scarcity is the lack of sufficient available water resources to meet water needs within a region . It affects every continent and around 2.8 billion people around the world at least one month out of every year . More than 1.2 billion people lack access to clean drinking water . Water scarcity involves water shortage , water stress or deficits , and water crisis . The relatively new concept of water stress is difficulty in obtaining sources of fresh water for use during a period of time ; it may result in further depletion and deterioration of available water resources . Water shortages may be caused by climate change , such as altered weather-patterns ( including droughts or floods ) , increased pollution , and increased human demand and overuse of water . The term water crisis labels a situation where the available potable , unpolluted water within a region is less than that region 's demand . Two converging phenomena drive water scarcity : growing freshwater use and depletion of usable freshwater resources . Water scarcity can result from two mechanisms : physical ( absolute ) water scarcity economic water scarcity Physical water scarcity results from inadequate natural water resources to supply a region 's demand , and economic water scarcity results from poor management of the sufficient available water resources . According to the United Nations Development Programme , the latter is found more often to be the cause of countries or regions experiencing water scarcity , as most countries or regions have enough water to meet household , industrial , agricultural , and environmental needs , but lack the means to provide it in an accessible manner . Many countries and governments aim to reduce water scarcity . The UN recognizes the importance of reducing the number of people without sustainable access to clean water and sanitation . The Millennium Development Goals within the United Nations Millennium Declaration aimed by 2015 to `` halve the proportion of people who are unable to reach or to afford safe drinking water . ''
449	Sea_level_rise	So it's clear now we're not seeing dangerous global warming, and the climate models are wrong.	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 .
914	Wind_power	The Clean Power Plan, a major component of fulfilling the agreement, would spike energy costs for working and middle-class Texans by 16% by 2030, according to the Economic Reliability Council of Texas	Wind power Wind power is the use of air flow through wind turbines to mechanically power generators for electric power . Wind power , as an alternative to burning fossil fuels , is plentiful , renewable , widely distributed , clean , produces no greenhouse gas emissions during operation , consumes no water , and uses little land . The net effects on the environment are far less problematic than those of nonrenewable power sources . Wind farms consist of many individual wind turbines which are connected to the electric power transmission network . Onshore wind is an inexpensive source of electric power , competitive with or in many places cheaper than coal or gas plants . Offshore wind is steadier and stronger than on land , and offshore farms have less visual impact , but construction and maintenance costs are considerably higher . Small onshore wind farms can feed some energy into the grid or provide electric power to isolated off-grid locations . Wind power gives variable power which is very consistent from year to year but which has significant variation over shorter time scales . It is therefore used in conjunction with other electric power sources to give a reliable supply . As the proportion of wind power in a region increases , a need to upgrade the grid , and a lowered ability to supplant conventional production can occur . Power management techniques such as having excess capacity , geographically distributed turbines , dispatchable backing sources , sufficient hydroelectric power , exporting and importing power to neighboring areas , using vehicle-to-grid strategies or reducing demand when wind production is low , can in many cases overcome these problems . In addition , weather forecasting permits the electric power network to be readied for the predictable variations in production that occur . As of 2015 , Denmark generates 40 % of its electric power from wind , and at least 83 other countries around the world are using wind power to supply their electric power grids . In 2014 global wind power capacity expanded 16 % to 369,553 MW . Yearly wind energy production is also growing rapidly and has reached around 4 % of worldwide electric power usage , 11.4 % in the EU .
1622	Effective_temperature	Postma disproved the greenhouse effect.	Effective temperature The effective temperature of a body such as a star or planet is the temperature of a black body that would emit the same total amount of electromagnetic radiation . Effective temperature is often used as an estimate of a body 's surface temperature when the body 's emissivity curve ( as a function of wavelength ) is not known . When the star 's or planet 's net emissivity in the relevant wavelength band is less than unity ( less than that of a black body ) , the actual temperature of the body will be higher than the effective temperature . The net emissivity may be low due to surface or atmospheric properties , including greenhouse effect .
868	Spanish_flu	In Alaska, already, researchers have discovered remnants of the 1918 flu that infected as many as 500 million and killed as many as 100 million"	Spanish flu The Spanish flu, also known as the 1918 flu pandemic, was an unusually deadly influenza pandemic caused by the H1N1 influenza A virus. Lasting from February 1918 to April 1920, it infected 500 million people – about a third of the world's population at the time – in four successive waves. The death toll is typically estimated to have been somewhere between 17 million and 50 million, and possibly as high as 100 million, making it one of the deadliest pandemics in human history. The first observations of illness and mortality were documented in the United States (in Kansas and New York City, and months before, in December 1917, at Camp Greene, North Carolina), France, Germany, and the United Kingdom. To maintain morale, World War I censors minimized these early reports. Newspapers were free to report the epidemic's effects in neutral Spain, such as the grave illness of King Alfonso XIII, and these stories created a false impression of Spain as especially hard hit. This gave rise to the name "Spanish" flu. Historical and epidemiological data are inadequate to identify with certainty the pandemic's geographic origin, with varying views as to its location.
1235	Earth	"During ice ages, caused by wobbles in the Earth's orbit, sea levels dropped more than 400 feet as ice piled up on land.	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 .
65	Wind_turbine	A windmill could spin until it falls apart and never generate as much energy as was invested in building it.	Wind turbine A wind turbine is a device that converts the wind 's kinetic energy into electrical power . Wind turbines are manufactured in a wide range of vertical and horizontal axis types . The smallest turbines are used for applications such as battery charging for auxiliary power for boats or caravans or to power traffic warning signs . Slightly larger turbines can be used for making contributions to a domestic power supply while selling unused power back to the utility supplier via the electrical grid . Arrays of large turbines , known as wind farms , are becoming an increasingly important source of intermittent renewable energy and are used by many countries as part of a strategy to reduce their reliance on fossil fuels .
1367	Eocene	But we do have other reliable indicators of temperatures before the late 1800s, and the evidence shows temperatures have been warmer than today for most of the past several thousand years, including warmer-than-present temperatures for most of the human civilization time period	Eocene The Eocene ( -LSB- pronˈiːəˌsiːn , _ ˈiːoʊ - -RSB- ) Epoch , lasting from , is a major division of the geologic timescale and the second epoch of the Paleogene Period in the Cenozoic Era . The Eocene spans the time from the end of the Paleocene Epoch to the beginning of the Oligocene Epoch . The start of the Eocene is marked by a brief period in which the concentration of the carbon isotope 13C in the atmosphere was exceptionally low in comparison with the more common isotope 12C . The end is set at a major extinction event called the Grande Coupure ( the `` Great Break '' in continuity ) or the Eocene -- Oligocene extinction event , which may be related to the impact of one or more large bolides in Siberia and in what is now Chesapeake Bay . As with other geologic periods , the strata that define the start and end of the epoch are well identified , though their exact dates are slightly uncertain . The name Eocene comes from the Ancient Greek ἠώς ( ēṓs , `` dawn '' ) and καινός ( kainós , `` new '' ) and refers to the `` dawn '' of modern ( ` new ' ) fauna that appeared during the epoch .
1544	Arctic_oscillation	Arctic icemelt is a natural cycle.	Arctic oscillation The Arctic oscillation ( AO ) or Northern Annular Mode/Northern Hemisphere Annular Mode ( NAM ) is an index ( which varies over time with no particular periodicity ) of the dominant pattern of non-seasonal sea-level pressure variations north of 20N latitude , and it is characterized by pressure anomalies of one sign in the Arctic with the opposite anomalies centered about 37 -- 45N . The AO is believed by climatologists to be causally related to , and thus partially predictive of , weather patterns in locations many thousands of miles away , including many of the major population centers of Europe and North America . NASA climatologist Dr. James E. Hansen explained the mechanism by which the AO affects weather at points so distant from the Arctic , as follows : `` The degree to which Arctic air penetrates into middle latitudes is related to the AO index , which is defined by surface atmospheric pressure patterns . When the AO index is positive , surface pressure is low in the polar region . This helps the middle latitude jet stream to blow strongly and consistently from west to east , thus keeping cold Arctic air locked in the polar region . When the AO index is negative , there tends to be high pressure in the polar region , weaker zonal winds , and greater movement of frigid polar air into middle latitudes . '' This zonally symmetric seesaw between sea level pressures in polar and temperate latitudes was first identified by Edward Lorenz and named in 1998 by David W.J. Thompson and John Michael Wallace . The North Atlantic oscillation ( NAO ) is a close relative of the AO and there exist arguments about whether one or the other is more fundamentally representative of the atmosphere 's dynamics ; Ambaum et al. argue that the NAO can be identified in a more physically meaningful way . Over most of the past century , the Arctic Oscillation alternated between its positive and negative phases . Starting in the 1970s the oscillation has trended to more of a positive phase when averaged using a 60-day running mean , though it has trended to a more neutral state in the last decade . The oscillation still fluctuates stochastically between negative and positive values on daily , monthly , seasonal and annual time scales , although , despite its stochastic nature , meteorologists have attained high levels of predictive accuracy in recent times , at least for the shorter term forecasts . ( The correlation between actual observations and the 7-day mean GFS ensemble AO forecasts is approximately 0.9 , a figure at the high end for that statistic . ) The National Snow and Ice Data Center describes the effects of the AO in some detail : `` In the positive phase , higher pressure at midlatitudes drives ocean storms farther north , and changes in the circulation pattern bring wetter weather to Alaska , Scotland and Scandinavia , as well as drier conditions to the western United States and the Mediterranean . In the positive phase , frigid winter air does not extend as far into the middle of North America as it would during the negative phase of the oscillation . This keeps much of the United States east of the Rocky Mountains warmer than normal , but leaves Greenland and Newfoundland colder than usual . Weather patterns in the negative phase are in general `` opposite '' to those of the positive phase . '' Climatologists are now routinely invoking the Arctic Oscillation in their official public explanations for extremes of weather . The following statement from the National Oceanic and Atmospheric Administration 's National Climatic Data Center : State of the Climate December 2010 which uses the phrase `` negative Arctic Oscillation '' four times , is very representative of this increasing tendency : `` Cold arctic air gripped western Europe in the first three weeks of December . Two major snowstorms , icy conditions , and frigid temperatures wreaked havoc across much of the region ... The harsh winter weather was attributed to a negative Arctic Oscillation , which is a climate pattern that influences weather in the Northern Hemisphere . A very persistent , strong ridge of high pressure , or ` blocking system ' , near Greenland allowed cold Arctic air to slide south into Europe . Europe was not the only region in the Northern Hemisphere affected by the Arctic Oscillation . A large snow storm and frigid temperatures affected much of the Midwest United States on December 10 -- 13 ... '' A further , quite graphic illustration of the effects of the negative phase of the oscillation occurred in February 2010 . In that month , the Arctic Oscillation reached its most negative monthly mean value , − 4.266 , in the entire post-1950 era ( the period of accurate record-keeping ) . That month was characterized by three separate historic snowstorms that occurred in the mid-Atlantic region of the United States . The first storm dumped 25 in on Baltimore , Maryland , on February 5 -- 6 , and then a second storm dumped 19.5 in on February 9 -- 10 . In New York City , a separate storm deposited 20.9 in on February 25 -- 26 . This kind of snowstorm activity is as anomalous and extreme as the negative AO value itself . Similarly , the greatest negative value for the AO since 1950 in January was − 3.767 in 1977 , which coincided with the coldest mean January temperature in New York City , Washington , D.C. , Baltimore , and many other mid-Atlantic locations in that span of time . And though the January AO has been negative only 60.6 % of the time between 1950 and 2010 , 9 of the 10 coldest Januarys in New York City since 1950 have coincided with negative AOs . However , the correlation between sharply negative Arctic Oscillations and excessive winter cold and snow in regions vulnerable in that way to these negative AOs should not be overstated . It is by no means a simple , one-to-one equivalence . An extreme Arctic Oscillation does not necessarily mean extreme weather will occur . For example , since 1950 , eight out of the 10 coldest Januarys in New York did not coincide with the 10 lowest January AO values . And the fourth warmest January there since 1950 coincided with one of those 10 most negative AOs . So , although many climatologists believe that the Arctic Oscillation affects the probability of certain weather events occurring in certain places , the heightened chance of a phenomenon by no means assures it , nor does the lessened likelihood exclude it . Further , the precise value of the AO index only imperfectly reflects the severity of the weather associated with it .
152	Climate_change_(general_concept)	"Catherine Senior, head of understanding climate change at the Met Office Hadley Centre, said more studies and more data were needed to fully understand the role of clouds and aerosols.	Climate change (general concept) Climate variability includes all the variations in the climate that last longer than individual weather events, whereas the term climate change only refers to those variations that persist for a longer period of time, typically decades or more. In the time since the industrial revolution the climate has increasingly been affected by human activities that are causing global warming and climate change.The climate system receives nearly all of its energy from the sun. The climate system also radiates energy to outer space. The balance of incoming and outgoing energy, and the passage of the energy through the climate system, determines Earth\'s energy budget. When the incoming energy is greater than the outgoing energy, earth\'s energy budget is positive and the climate system is warming. If more energy goes out, the energy budget is negative and earth experiences cooling.\nThe energy moving through Earth\'s climate system finds expression in weather, varying on geographic scales and time. Long-term averages and variability of weather in a region constitute the region\'s climate. Such changes can be the result of "internal variability", when natural processes inherent to the various parts of the climate system alter the distribution of energy. Examples include variability in ocean basins such as the Pacific decadal oscillation and Atlantic multidecadal oscillation. Climate variability can also result from external forcing, when events outside of the climate system\'s components nonetheless produce changes within the system. Examples include changes in solar output and volcanism.\nClimate variability has consequences for sea level changes, plant life, and mass extinctions; it also affects human societies.
2178	Global_warming_hiatus	Loehle and Scafetta find a 60 year cycle causing 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 .
1020	Cretaceous–Paleogene_extinction_event	"The global reef crisis does not necessarily mean extinction for coral species.	Cretaceous–Paleogene extinction event The Cretaceous -- Paleogene ( K -- Pg ) extinction event , also known as the Cretaceous -- Tertiary ( K -- T ) extinction , was a mass extinction of some three-quarters of the plant and animal species on Earth that occurred over a geologically short period of time approximately 65 million years ago . With the exception of some ectothermic species like the leatherback sea turtle and crocodiles , no tetrapods weighing more than 25 kg survived . It marked the end of the Cretaceous period and with it , the entire Mesozoic Era , opening the Cenozoic Era that continues today . In the geologic record , the K -- Pg event is marked by a thin layer of sediment called the K -- Pg boundary , which can be found throughout the world in marine and terrestrial rocks . The boundary clay shows high levels of the metal iridium , which is rare in the Earth 's crust but abundant in asteroids . As originally proposed in 1980 by a team of scientists led by Luis Alvarez , it is now generally thought that the K -- Pg extinction was caused by a massive comet or asteroid impact , estimated to be 10 km wide , 66 million years ago and its catastrophic effects on the global environment , including a lingering impact winter that made it impossible for plants and plankton to carry out photosynthesis . The impact hypothesis , also known as the Alvarez hypothesis , was bolstered by the discovery of the 180 km Chicxulub crater in the Gulf of Mexico in the early 1990s , which provided conclusive evidence that the K -- Pg boundary clay represented debris from an asteroid impact . The fact that the extinctions occurred at the same time as the impact provides strong situational evidence that the K -- Pg extinction was caused by the asteroid . It was possibly accelerated by the creation of the Deccan Traps . However , some scientists maintain the extinction was caused or exacerbated by other factors , such as volcanic eruptions , climate change , or sea level change , separately or together . A wide range of species perished in the K -- Pg extinction . The best-known victims are the non-avian dinosaurs . However , the extinction also destroyed a plethora of other terrestrial organisms , including certain mammals , pterosaurs , birds , lizards , insects , and plants . In the oceans , the K -- Pg extinction killed off plesiosaurs and the giant marine lizards ( Mosasauridae ) and devastated fish , sharks , mollusks ( especially ammonites , which became extinct ) and many species of plankton . It is estimated that 75 % or more of all species on Earth vanished . Yet the devastation caused by the extinction also provided evolutionary opportunities . In the wake of the extinction , many groups underwent remarkable adaptive radiations -- a sudden and prolific divergence into new forms and species within the disrupted and emptied ecological niches resulting from the event . Mammals in particular diversified in the Paleogene , producing new forms such as horses , whales , bats , and primates . Birds , fish and perhaps lizards also radiated .
2553	Watts_Up_With_That?	The climate debate is, in reality, about a 1.6 watts per square metre or 0.5 per cent discrepancy in the poorly known planetary energy balance."	Watts Up With That? Watts Up With That ? ( or WUWT ) is a blog promoting climate change denial that was created by Anthony Watts in 2006 . The blog predominantly discusses climate issues with a focus on anthropogenic climate change , generally accommodating beliefs that are in opposition to the scientific consensus on climate change . Contributors include Christopher Monckton and Fred Singer as guest authors . In November 2009 , the blog was one of the first websites to publish emails and documents from the Climatic Research Unit controversy , and a driving force behind its coverage . In the early months of 2010 , it was reported the site might be `` the most read climate blog in the world , '' and in 2013 Michael E. Mann referred to it as the leading climate change denial blog .
1135	Coral_bleaching	Scientists confirm a mass bleaching event on the Great Barrier Reef this year has killed more corals than ever before, with more than two thirds destroyed across large swathes of the biodiverse site.	Coral bleaching Coral bleaching occurs when coral polyps expel algae that lives inside their tissues . Normally , coral polyps live in an endosymbiotic relationship with the algae and that relationship is crucial for the coral and hence for the health of the whole reef . Bleached corals continue to live . But as the algae provide the coral with 90 % of its energy , after expelling the algae the coral begins to starve . Above-average sea water temperatures caused by global warming have been identified as a leading cause for coral bleaching worldwide . Between 2014 and 2016 , the longest global bleaching events ever were recorded . According to the United Nations Environment Programme , these bleaching events killed coral on an unprecedented scale . In 2016 , bleaching hit 90 percent of coral on the Great Barrier Reef and killed 29 percent of the reef 's coral . In 2017 , the bleaching further expanded to areas of the park that were previously spared , such as the central one . __ TOC __
861	Melbourne	None of these places, which today supply much of the world's food, will be reliable sources of any.	Melbourne Melbourne ( -LSB- ˈmɛlbərn -RSB- ) is the capital and most populous city of the Australian state of Victoria , and the second-most populous city in Australia and Oceania . The name `` Melbourne '' refers to an urban agglomeration spanning 9900 km2 , which comprises the broader metropolitan area , as well as being the common name for its city centre . The metropolis is located on the large natural bay of Port Phillip and expands into the hinterlands towards the Dandenong and Macedon mountain ranges , Mornington Peninsula and Yarra Valley . Melbourne consists of 31 municipalities . It has a population of 4,641,636 , and its inhabitants are called Melburnians . Founded by free settlers from the British Crown colony of Van Diemen 's Land on 30 August 1835 , in what was then the colony of New South Wales , it was incorporated as a Crown settlement in 1837 . It was named `` Melbourne '' by the Governor of New South Wales , Sir Richard Bourke , in honour of the British Prime Minister of the day , William Lamb , 2nd Viscount Melbourne . It was officially declared a city by Queen Victoria , to whom Lord Melbourne was close , in 1847 , after which it became the capital of the newly founded colony of Victoria in 1851 . During the Victorian gold rush of the 1850s , it was transformed into one of the world 's largest and wealthiest cities . After the federation of Australia in 1901 , it served as the nation 's interim seat of government until 1927 . Melbourne rates highly in education , entertainment , health care , research and development , tourism and sport , making it the world 's most liveable city -- for the sixth year in a row in 2016 , according to the Economist Intelligence Unit . It is a leading financial centre in the Asia-Pacific region , and ranks among the top 30 cities in the world in the Global Financial Centres Index . Referred to as Australia 's `` cultural capital '' , it is the birthplace of Australian impressionism , Australian rules football , the Australian film and television industries , and Australian contemporary dance . It is recognised as a UNESCO City of Literature and a major centre for street art , music and theatre . It is home to many of Australia 's largest and oldest cultural institutions such as the Melbourne Cricket Ground , the National Gallery of Victoria , the State Library of Victoria and the UNESCO World Heritage-listed Royal Exhibition Building . It was the host city of the 1956 Summer Olympics and the 2006 Commonwealth Games . The main passenger airport serving the metropolis and the state is Melbourne Airport ( also called Tullamarine Airport ) , the second busiest in Australia . The Port of Melbourne is Australia 's busiest seaport for containerised and general cargo . Melbourne has an extensive transport network . The main metropolitan train terminus is Flinders Street Station , and the main regional train and coach terminus is Southern Cross Station . Melbourne is also home to Australia 's most extensive freeway network and has the world 's largest urban tram network .
2040	Paris_Agreement	Any action by Australia to reduce emissions of fossil fuels would not help to protect the reef unless there is an effective international agreement by major emitters.	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 .
1591	Carbon_dioxide	Murry Salby finds CO2 rise is natural.	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 .
1451	Carbon_dioxide	The planet's average surface temperature has risen about 1.62 degrees Fahrenheit (0.9 degrees Celsius) since the late 19th century, a change driven largely by increased carbon dioxide and other human-made emissions into the atmosphere.	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 .
2584	Global_warming	Once the atmosphere reaches a saturation point, additional input of CO2 will not really have any major impact.	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 .
2620	Runaway_greenhouse_effect	"...the largest of all the positive or temperature-amplifying feedbacks in the UN's arsenal is the water-vapor feedback.	Runaway greenhouse effect A runaway greenhouse effect is a process in which a net positive feedback between surface temperature and atmospheric opacity increases the strength of the greenhouse effect on a planet until its oceans boil away . An example of this is believed to have happened in the early history of Venus . On the Earth , the IPCC states that `` a ` runaway greenhouse effect ' -- analogous to -LSB- that of -RSB- Venus -- appears to have virtually no chance of being induced by anthropogenic activities . '' Other large-scale climate changes are sometimes loosely called a `` runaway greenhouse effect '' although it is not an appropriate description . For example , it has been hypothesized that large releases of greenhouse gases may have occurred concurrently with the Permian -- Triassic extinction event or Paleocene -- Eocene Thermal Maximum . Other terms , such as `` abrupt climate change '' , or tipping points could be used when describing such scenarios .
1141	Climate_change_in_the_Arctic	"While record low sea ice is nothing new in the Arctic, this is a surprising turn of events for the Antarctic.	Climate change in the Arctic The effects of global warming in the Arctic , or climate change in the Arctic include rising temperatures , loss of sea ice , and melting of the Greenland ice sheet with a related cold temperature anomaly , observed in recent years . Potential methane release from the region , especially through the thawing of permafrost and methane clathrates , is also a concern . The Arctic warms twice as fast compared to the rest of the world . The pronounced warming signal , the amplified response of the Arctic to global warming , it is often seen as a leading indicator of global warming . The melting of Greenland 's ice sheet is linked to polar amplification . According to a study published in 2016 , about 0.5 ◦ C of the warming in the Arctic has been attributed to reductions in sulfate aerosols in Europe since 1980 .
1893	Effects_of_global_warming_on_human_health	Global warming leads to much quicker spread of the Zika virus because the increased temperature, "makes mosquitoes mature faster, . . .	Effects of global warming on human health The effects of global warming include effects on human health . The observed and projected increased frequency and severity of climate related impacts will further exacerbate the effects on human health . This article describes some of those effects on individuals and populations .
2445	Little_Ice_Age	When all forcings are combined, they show good correlation to global temperature throughout the 20th century including the mid-century cooling period.	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 .
2455	Anoxic_event	When CO2 levels were higher in the past, solar levels were also lower.	Anoxic event Oceanic anoxic events or anoxic events ( anoxia conditions ) refer to intervals in the Earth 's past where portions of oceans become depleted in oxygen ( O2 ) at depths over a large geographic area . During some of these events , euxinia , waters that contained hydrogen sulfide , developed . Although anoxic events have not happened for millions of years , the geological record shows that they happened many times in the past . Anoxic events coincided with several mass extinctions and may have contributed to them . These mass extinctions include some that geobiologists use as time markers in biostratigraphic dating . Many geologists believe oceanic anoxic events are strongly linked to slowing of ocean circulation , climatic warming , and elevated levels of greenhouse gases . Researchers have proposed enhanced volcanism ( the release of CO2 ) as the `` central external trigger for euxinia '' .
1614	Polar_ice_cap	Arctic sea ice extent was lower in the past.	Polar ice cap A polar ice cap or polar cap is a high-latitude region of a planet , dwarf planet , or natural satellite that is covered in ice . There are no requirements with respect to size or composition for a body of ice to be termed a polar ice cap , nor any geological requirement for it to be over land ; only that it must be a body of solid phase matter in the polar region . This causes the term `` polar ice cap '' to be something of a misnomer , as the term ice cap itself is applied more narrowly to bodies that are over land , and cover less than 50,000 km ² : larger bodies are referred to as ice sheets . The composition of the ice will vary . For example , Earth 's polar caps are mainly water ice , whereas Mars 's polar ice caps are a mixture of solid carbon dioxide and water ice . Polar ice caps form because high-latitude regions receive less energy in the form of solar radiation from the Sun than equatorial regions , resulting in lower surface temperatures . Earth 's polar caps have changed dramatically over the last 12,000 years . Seasonal variations of the ice caps takes place due to varied solar energy absorption as the planet or moon revolves around the Sun . Additionally , in geologic time scales , the ice caps may grow or shrink due to climate variation .
2886	Global_warming	As it happens, the writer of that October 2009 e-mail—Kevin Trenberth, a lead author of the warmist bible, the 2007 Intergovernmental Panel on Climate Change (IPCC) report—told Congress two years ago that evidence for manmade warming is "unequivocal.	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 .
2763	Ice_age	The long term trend from albedo is of cooling.	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 .
819	Scientific_consensus_on_climate_change	Climate change need not endanger anyone"	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.
446	Natural_gas	It's not carbon dioxide, it's not methane… Scientists estimate that somewhere between 75% and 90% of Earth greenhouse effect is caused by water vapor in clouds."	Natural gas Natural gas is a naturally occurring hydrocarbon gas mixture consisting primarily of methane , but commonly including varying amounts of other higher alkanes , and sometimes a small percentage of carbon dioxide , nitrogen , hydrogen sulfide , or helium . It is formed when layers of decomposing plant and animal matter are exposed to intense heat and pressure under the surface of the Earth over millions of years . The energy that the plants originally obtained from the sun is stored in the form of chemical bonds in the gas . Natural gas is a fossil fuel used as a source of energy for heating , cooking , and electricity generation . It is also used as fuel for vehicles and as a chemical feedstock in the manufacture of plastics and other commercially important organic chemicals . Fossil fuel based natural gas is a non-renewable resource . Natural gas is found in deep underground rock formations or associated with other hydrocarbon reservoirs in coal beds and as methane clathrates . Petroleum is another resource and fossil fuel found in close proximity to and with natural gas . Most natural gas was created over time by two mechanisms : biogenic and thermogenic . Biogenic gas is created by methanogenic organisms in marshes , bogs , landfills , and shallow sediments . Deeper in the earth , at greater temperature and pressure , thermogenic gas is created from buried organic material . In petroleum production gas is often burnt as flare gas . The World Bank estimates that over 150 cubic kilometers of natural gas are flared or vented annually . Before natural gas can be used as a fuel , most , but not all , must be processed to remove impurities , including water , to meet the specifications of marketable natural gas . The by-products of this processing include : ethane , propane , butanes , pentanes , and higher molecular weight hydrocarbons , hydrogen sulfide ( which may be converted into pure sulfur ) , carbon dioxide , water vapor , and sometimes helium and nitrogen . Natural gas is often informally referred to simply as `` gas '' , especially when compared to other energy sources such as oil or coal . However , it is not to be confused with gasoline , especially in North America , where the term gasoline is often shortened in colloquial usage to gas . Natural gas was used by the Chinese in about 500 BCE ( possibly even 1000 BCE ) . They discovered a way to transport gas seeping from the ground in crude pipelines of bamboo to where it was used to boil salt water to extract the salt , in the Ziliujing District of Sichuan . The world 's first industrial extraction of natural gas started at Fredonia , New York , United States in 1825 . By 2009 , 66 000 km ³ ( or 8 % ) had been used out of the total 850 000 km ³ of estimated remaining recoverable reserves of natural gas . Based on an estimated 2015 world consumption rate of about 3400 km ³ of gas per year , the total estimated remaining economically recoverable reserves of natural gas would last 250 years at current consumption rates . An annual increase in usage of 2 -- 3 % could result in currently recoverable reserves lasting significantly less , perhaps as few as 80 to 100 years .
512	Carbon_dioxide	water vapour has been the main greenhouse gas and carbon dioxide has had a minuscule effect on global climate	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 .
2523	Global_warming	This is called the "atmospheric greenhouse effect", and without it the Earth's surface would be much colder.	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 .

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