Future generations of Americans can expect to spend 25 days a year sweltering in temperatures above 100 degrees F (38 degrees C), with climate change on course to turn the country into a hotter, drier, and more disaster-prone place.
The National Climate Assessment, released in draft form on Friday, provided the fullest picture to date of the real-time effects of climate change on U.S. life, and the most likely consequences for the future.
The 1,000-page report, the work of the more than 300 government scientists and outside experts, was unequivocal on the human causes of climate change, and on the links between climate change and extreme weather.
“Climate change is already affecting the American people,” the draft report said. “Certain types of weather events have become more frequent and/or intense including heat waves, heavy downpours and in some regions floods and drought. Sea level is rising, oceans are becoming more acidic, and glaciers and Arctic sea ice are melting.”
The report, which is not due for adoption until 2014, was produced to guide federal, state, and city governments in America in making long-term plans.
By the end of the 21st century, climate change is expected to result in increased risk of asthma and other public health emergencies, widespread power blackouts, mass transit shutdowns, and possibly shortages of food.
“Proactively preparing for climate change can reduce impacts, while also facilitating a more rapid and efficient response to changes as they happen,” said Katharine Jacobs, the director of the National Climate Assessment.
The report will be open for public comment on Monday.
Environmental groups said they hoped the report would provide Barack Obama with the scientific evidence to push for measures that would slow or halt the rate of climate change — sparing the country some of the worst effects.
The report states clearly that the steps taken by Obama so far to reduce emissions are “not close to sufficient” to prevent the most severe consequences of climate change.
“As climate change and its impacts are becoming more prevalent, Americans face choices,” the report said. “Beyond the next few decades, the amount of climate change will still largely be determined by the choices society makes about emissions. Lower emissions mean less future warming and less severe impacts. Higher emissions would mean more warming and more severe impacts.”
As the report made clear: No place in America had gone untouched by climate change. Nowhere would be entirely immune from the effects of future climate change.
Some of those changes are already evident: 2012 was by far the hottest year on record, fully a degree hotter than the last such record — an off-the-charts rate of increase.
Those high temperatures were on course to continue for the rest of the century, the draft report said. It noted that average U.S. temperatures had increased by about 1.5 degrees F since 1895, with more than 80 percent of this increase since 1980.
The rise will be even steeper in future, with the next few decades projected for temperatures 2 to 4 degrees warmer in most areas. By 2100, if climate change continues on its present course, the country can expect to see 25 days a year with temperatures above 100 degrees F.
Nighttime temperatures will also stay high, providing little respite from the heat.
Certain regions are projected to heat up even sooner. West Virginia, Maryland, and Delaware can expect a doubling of days hotter than 95 degrees by the 2050s. In Texas and Oklahoma, the draft report doubled the probability of extreme heat events.
Those extreme temperatures would also exact a toll on public health, with worsening air pollution, and on infrastructure, increasing the load for aging power plants.
But nowhere will see changes as extreme as Alaska, the report said.
“The most dramatic evidence is in Alaska, where average temperatures have increased more than twice as fast as the rest of the country,” the draft report said. “Of all the climate-related changes in the U.S., the rapid decline of Arctic sea ice cover in the last decade may be the most striking of all.”
Other regions will face different extreme weather scenarios. The Northeast, in particular, is at risk of coastal flooding because of sea-level rise and storm surges, as well as river flooding, because of an increase in heavy downpours.
“The north-east has experienced a greater increase in extreme precipitation over the past few decades than any other region in the U.S.,” the report said. Between 1958 and 2010, the Northeast saw a 74 percent increase in heavy downpours.
The Midwest was projected to enjoy a longer growing season — but also an increased risk of extreme events like last year’s drought. By mid-century, the combination of temperature increases and heavy rainfall or drought were expected to pull down yields of major U.S. food crops, the report warned, threatening both American and global food security.
The report is the most ambitious scientific exercise ever undertaken to catalogue the real-time effects of climate change, and predict possible outcomes in the future.
It involved more than 300 government scientists and outside experts, compared to around 30 during the last such effort when George W. Bush was president. Its findings were also much broader in scope, Jacobs said.
There were still unknowns though, the report conceded, especially about how the loss of sea ice in Greenland and Antarctica will affect future sea-level rise.
Campaign groups said they hoped the report would spur Obama to act on climate change in his second term. “The draft assessment offers a perfect opportunity for President Obama at the outset of his second term,” said Lou Leonard, director of the climate change program for the World Wildlife Fund. “When a similar report was released in 2009, the administration largely swept it under the rug. This time, the president should use it to kick-start a national conversation on climate change.”
However, the White House was exceedingly cautious on the draft release, noting in a blog post: “The draft NCA is a scientific document — not a policy document — and does not make recommendations regarding actions that might be taken in response to climate change.”
"""Kizazi kijacho cha Wamarekani kinaweza kutarajia kutumia siku 25 kwa mwaka katika joto la juu ya 38 ° C, na mabadiliko ya hali ya hewa yanaelekea kugeuza nchi kuwa mahali pa joto zaidi, kavu zaidi, na mahali pa msiba zaidi.""" Tathmini ya Taifa ya Hali ya Hewa, iliyotolewa katika fomu ya rasimu Ijumaa, ilitoa picha kamili zaidi hadi sasa ya athari za wakati halisi za mabadiliko ya hali ya hewa kwa maisha ya Marekani na matokeo ya uwezekano mkubwa kwa siku zijazo. Ripoti hiyo yenye kurasa 1,000, iliyochaguliwa na wanasayansi zaidi ya 300 wa serikali na wataalamu wa nje, ilikuwa wazi kabisa juu ya sababu za binadamu za mabadiliko ya hali ya hewa, na juu ya uhusiano kati ya mabadiliko ya hali ya hewa na hali ya hewa kali. "Mabadiliko ya hali ya hewa tayari yanawaathiri watu wa Marekani", ripoti hiyo ilisema. <unk> Aina fulani za matukio ya hali ya hewa yamekuwa ya mara kwa mara na/au kali ikiwa ni pamoja na mawimbi ya joto, mvua kubwa na katika baadhi ya mikoa mafuriko na ukame. "Lakini kwa sababu ya kuongezeka kwa kiwango cha maji baharini, bahari zinaongezeka kuwa na asidi, barafu na barafu za baharini za Aktiki zinayeyuka, ripoti hiyo, ambayo haitaidhinishwa hadi mwaka 2014, ilitengenezwa ili kuongoza serikali za serikali za Marekani, serikali za majimbo na serikali za miji katika kufanya mipango ya muda mrefu.""" "Mwisho wa karne ya 21, mabadiliko ya hali ya hewa yanatarajiwa kusababisha kuongezeka kwa hatari ya ugonjwa wa pumu na hali nyingine za dharura za afya ya umma, kuzima kwa umeme kwa wingi, kuzima kwa usafiri wa umma, na uwezekano wa upungufu wa chakula. """ "Kujitayarisha kwa bidii kwa mabadiliko ya hali ya hewa kunaweza kupunguza athari, wakati pia kuwezesha majibu ya haraka na yenye ufanisi kwa mabadiliko yanayotokea, "alisema Katharine Jacobs, mkurugenzi wa Tathmini ya Taifa ya Hali ya Hewa." Ripoti hiyo itafunguliwa kwa maoni ya umma Jumatatu. Makundi ya mazingira yalisema yanatarajia ripoti hiyo itampa Obama ushahidi wa kisayansi wa kushinikiza hatua ambazo zitapunguza au kusimamisha kiwango cha mabadiliko ya hali ya hewa - na kuokoa nchi baadhi ya athari mbaya zaidi. Ripoti hiyo inasema waziwazi kwamba hatua zilizochukuliwa na Obama hadi sasa kupunguza uzalishaji ni "si karibu na kutosha" kuzuia matokeo mabaya zaidi ya mabadiliko ya hali ya hewa. "Kama mabadiliko ya hali ya hewa na athari zake zinakuwa za kawaida zaidi, Wamarekani wanakabiliwa na chaguzi", ripoti hiyo ilisema. "Zaidi ya miongo michache ijayo, kiwango cha mabadiliko ya hali ya hewa bado kitatawaliwa kwa kiasi kikubwa na chaguzi ambazo jamii hufanya kuhusu uzalishaji. """ Kupunguza uzalishaji kunamaanisha joto la chini la baadaye na athari mbaya zaidi. "Utoaji wa gesi ya gesi ya gesi ya gesi ya gesi ya gesi ya gesi ya gesi ya gesi ya gesi ya gesi ya gesi ya gesi ya gesi ya gesi ya gesi ya gesi ya gesi ya gesi ya gesi ya gesi ya gesi ya gesi ya gesi ya gesi ya gesi ya gesi ya gesi ya gesi ya gesi ya gesi ya gesi ya gesi ya gesi. """ Hakuna mahali popote ambapo mabadiliko ya hali ya hewa yatakuwa yasiyoathiri. Baadhi ya mabadiliko hayo tayari ni dhahiri: 2012 ilikuwa mwaka wa joto zaidi kwenye rekodi, kabisa digrii ya joto kuliko rekodi ya mwisho kama hiyo - kiwango cha ongezeko la chati. "Hatua hiyo ya joto la juu inatarajiwa kuendelea kwa muda mrefu zaidi katika karne hii,"" ilisema ripoti hiyo." "Kama ilivyotangulia, joto la wastani nchini Marekani liliongezeka kwa karibu digrii 1.5 F tangu mwaka wa 1895 na zaidi ya asilimia 80 ya ongezeko hilo tangu mwaka wa 1980.""" Ongezeko hilo litakuwa kubwa zaidi katika siku zijazo, na miongo michache ijayo inatarajiwa kuwa joto la joto la 2 hadi 4 digrii katika maeneo mengi. Kufikia mwaka 2100 ikiwa mabadiliko ya hali ya hewa yataendelea kwa mwendo wake wa sasa, nchi inaweza kutarajia kuona siku 25 kwa mwaka na joto juu ya digrii 100 F. Joto la usiku pia litabaki juu, na kutoa mapumziko kidogo kutoka kwa joto. Maeneo fulani yanatabiriwa kuwa yenye joto hata mapema zaidi. Virginia Magharibi, Maryland na Delaware zinatarajia kuongezeka kwa joto la joto zaidi ya nyuzi 95 katika miaka ya 2050. Katika Texas na Oklahoma, ripoti ya rasimu iliongeza mara mbili uwezekano wa matukio ya joto kali. Joto hilo kali pia litazidi kuathiri afya ya umma, na kuharibu uchafuzi wa hewa, na miundombinu, na kuongeza mzigo kwa mitambo ya umeme inayokuwa ikizidi kuharibika. Lakini hakuna mahali pengine ambapo mabadiliko yatakuwa makubwa kama Alaska, ripoti hiyo ilisema. "Ushahidi mkubwa zaidi uko Alaska, ambapo wastani wa joto umeongezeka kwa kasi zaidi ya mara mbili kuliko nchi nzima", ripoti hiyo ilisema. "Kutokana na mabadiliko yote ya hali ya hewa nchini Marekani, kupungua kwa haraka kwa barafu ya bahari ya Aktiki katika muongo uliopita kunaweza kuwa jambo la kushangaza zaidi. ""Mikoa mingine itakabiliwa na hali tofauti za hali ya hewa." Kaskazini mashariki ya nchi, hasa, iko katika hatari ya mafuriko ya pwani kwa sababu ya kuongezeka kwa kiwango cha bahari na mawimbi ya dhoruba, pamoja na mafuriko ya mito, kwa sababu ya ongezeko la mvua kubwa. "Kaskazini mashariki imepata ongezeko kubwa la mvua kubwa zaidi katika miongo michache iliyopita kuliko mkoa mwingine wowote nchini Marekani", ripoti hiyo ilisema. Kati ya mwaka 1958 na 2010, eneo la kaskazini-mashariki la Marekani liliona ongezeko la asilimia 74 la mvua kubwa. Midwest ilitabiriwa kufurahia msimu mrefu wa kukua <unk> lakini pia hatari iliyoongezeka ya matukio makali kama ukame wa mwaka jana. "Katika katikati ya karne hii, mchanganyiko wa ongezeko la joto na mvua nyingi au ukame unatarajiwa kupunguza mavuno ya mazao makuu ya chakula ya Marekani, ripoti hiyo ilionya, ikitishia usalama wa chakula wa Marekani na ulimwengu. """ Ripoti hiyo ni jaribio la kisayansi lenye matarajio makubwa zaidi kuwahi kufanywa ili kuorodhesha athari za mabadiliko ya hali ya hewa kwa wakati halisi, na kutabiri matokeo yanayowezekana katika siku zijazo. Majaribio hayo yalihusisha wanasayansi zaidi ya 300 wa serikali na wataalamu wa nje, ikilinganishwa na karibu 30 wakati wa juhudi za mwisho wakati George W. Bush alikuwa rais. Jacobs alisema kwamba matokeo yake yalikuwa na mwelekeo mkubwa zaidi. Hata hivyo, ripoti hiyo ilikiri kwamba bado kuna mambo ambayo hayajulikani, hasa kuhusu jinsi kupoteza barafu ya baharini huko Greenland na Antaktika kutaathiri ongezeko la kiwango cha bahari katika siku zijazo. Makundi ya kampeni yalisema yanatarajia ripoti hiyo itamchochea Obama kuchukua hatua dhidi ya mabadiliko ya hali ya hewa katika muhula wake wa pili. "Mapendekezo ya tathmini yanatoa fursa nzuri kwa Rais Obama mwanzoni mwa muhula wake wa pili,"" alisema Lou Leonard, mkurugenzi wa mpango wa mabadiliko ya hali ya hewa kwa Mfuko wa Dunia wa Wanyamapori. "Wakati ripoti kama hiyo ilitolewa mwaka 2009, utawala ulificha kwa kiasi kikubwa.""" "Wakati huo huo, Rais Obama alitoa taarifa ya kuangazia hatua za ""kuchukua hatua za kukabiliana na mabadiliko ya hali ya hewa"" na White House ilisema katika chapisho lake la blogu kwamba ""mkataba wa NCA ni hati ya kisayansi, sio hati ya sera, na hautoi mapendekezo kuhusu hatua zinazoweza kuchukuliwa kukabiliana na mabadiliko ya hali ya hewa."""