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温室効果ガス削減など、気候変動への国際的枠組み作りを協議する国連気候変動枠組条約第19回締結国会議（COP19）が11月11日から22日まで、ポーランドの首都ワルシャワで開幕する。
日本政府は新たに温室効果ガス削減目標として「05年比3・8%減」とする方針を固めている。朝日新聞デジタルは次のように伝えている。
新たなエネルギー政策が決まるまでの「暫定的な数字」（関係閣僚）として０５年比３・８％減とすることで決着した。前提となる原発比率は稼働中の原発がないため「ゼロ」とした。ただ、０５年比３・８％減は９０年比換算で温室効果ガスが３％以上増える計算で、ＣＯＰ１９で批判される可能性がある。
(朝日新聞デジタル「温室ガス05年比3.8%減 20年目標、各国に説明へ」2013/11/07 07:17)
COP19では、2008年から20年までの間に先進国全体で温室効果ガスを5.2%削減するという目標を定めた「京都議定書」に代わる新たな枠組みが決定する2015年までに、温室効果ガス削減や地球温暖化防止に向けた具体的な取り組みが途上国も含めて行えるかどうかがカギとなる。
京都議定書は、アメリカの離脱や中国・インドなどの新興国の経済発展がからみ、期待されたほどの成果が挙げられていない。気候変動に関する政府間パネル(IPCC)は今世紀末に地球の平均気温は最大4.8度上昇し、海面は82％上昇すると予測するなど、むしろ気候変動による温暖化が進行するのではないかという懸念が消えない。
COP19やIPCCで指摘される気候変動の影響は多岐に及ぶが、それらで言及されていない「深刻な影響」が進行しつつあるという専門家の指摘もある。
■ IPCCの報告書に記載されなかったもう一つの「脅威」
11月8日、IPCCによる地球温暖化の影響についての最新報告書草案がブロゴスフィア（ブログおよびブロガーで形成されたコミュニティ）にリークされた。草案では海氷の減少から、飢餓や猛暑による環境への脅威にさらされ穀物生産高が喪失することまで、さまざまな懸念が強調されている。
しかし、今回の報告書草案で言及されていないもう一つの懸念がある。それは、気候変動によって、長期的に持続し広範囲に蔓延する有害化学物質がもたらす大規模な環境破壊がさらに悪化する可能性があるということだ。
気候変動と有害化学物質――科学者たちに言わせると、地球環境への最大の脅威となるこの２つの要素は密接に関連しているようだ。
「我々はIPCCが設定した締め切りにぎりぎり間に合わなかった」と、ミズーリ州にあるアメリカ地質調査所コロンビア環境研究センターの生物学研究員マイケル・フーパー氏は語る。
フーパー氏は、2014年1月に発表される自身と他の科学者たちが携わった一連の研究について言及した。それは、IPCC第５次評価報告書の段階で気候変動の緩和をテーマにするIPCCの第三作業部会の検討材料から除外された後のものだ（2014年３月までにまとめられる予定の最終報告書までに変更される可能性もある）。新たな研究によると、地球温暖化によって、有機塩素系殺虫剤のような化学物質の拡散や濃度に影響を与えるかもしれないという点を強調している。同様に、気候変動が動物や人間がこうした化学物質に対する耐性を弱める可能性についても言及している。
その逆についても言及されている。地球環境が化学物質にさらされる規模が拡大すれば、ホッキョクグマや人間の赤ちゃんが極端な温度変化、暴風雨、食糧不足、そして気候変動によるさまざまな脅威に耐えられない可能性がある。
「気候変動はこうした化学物質がより毒性を高めることにもなる。そして人体により長期的に、より高濃縮に影響を及ぼすことになりそうだ」とフーパー氏は付け加えた。
■ 気候変動による経済的影響も拡大
気候変動は地球環境のみならず、地球全体の経済にも今後大きな影響を及ぼす予測がなされている。
イギリスのリスク評価会社メイプルクロフト社が10月30日に発表した「第6次気候変動脆弱性指数」によると、調査した193カ国のうち、2025年までに地球温暖化の気候変動によるリスクが高くなる国は67カ国で、世界全体の3割を占めるようになると予測している。
また、アジア開発銀行（ADB）の報告書によると、日本、中国、韓国、モンゴルのアジア4カ国は、「気候に左右されない」インフラを整備するために2050年までの間、毎年約230億ドル（約2兆2800億円）の負担増となると見込まれている。
地球環境、そして世界経済に多大な影響を及ぼずとみられる気候変動。「異常気象」「例年にない猛暑」「経験のない大雨」といった現象が日常の風景になりつつある今、もっとも見過ごしてはならない「脅威」と言えるかもしれない。
※気候変動が及ぼす地球環境、世界経済への影響について、みなさんのご意見をコメント欄にお寄せください。
※訳文を「海氷の減少から、飢餓や猛暑による環境への脅威にさらされ穀物生産高が喪失することまで」と修正しました（2013/11/10 22:25）
関連記事
気候変動で失われるかもしれないもの
Wine Tasting Parties(01 of25)
Winegrowers in France\'s Champagne region and scientists have already seen changes in the past 25 years, reported The New York Times last year. They have \"noted major changes in their vineyards, including an increased sugar content in the grapes from which they make their wine, with a consequent decrease in acidity, and a harvest time that regularly comes two weeks earlier than it once did.\"\n\nLast year, the Telegraph reported that Bordeaux, one of the world\'s most famous wine-producing regions, may be \"unsuitable for wine-growing by 2050.\" \n\nYale Environment 360 explains that many European wines are tied to a specific geographical area, creating a problem for regions which may soon find themselves most suited to a new kind of grape. \n\nIn the U.S., researchers at Stanford University found that climate change could mean \"50% less land suitable for cultivating premium wine grapes in high-value areas of Northern California.\"\n\nA 2006 study published in the Proceedings of the National Academy of Sciences found that \"up to 81 percent\" of \"premium-wine-grape production area\" could decline in the U.S. by the end of this century, reported Wired. Without any adaptation measures, wine-grape production could disappear from \"many areas\" of the country.\n\nWired notes, \"By the law of supply and demand, that suggests the best wines of tomorrow will cost even more than the ridiculous amounts they fetch today.\" (credit:Getty)
Winnie The Pooh's Key Plot Point(02 of25)
According to the USDA, bee populations are dropping nationwide. Wetter winters and rainy summers make it harder for bees to get out and about to collect, leaving them to starve or become malnourished and more prone to other diseases. This doesn\'t just mean a decline in honey. We rely on bees to pollinate crops. When bees disappear, many food crops could also die off. (credit:Flickr: Ano Lobb. @healthyrx)
Spring Break, Wohoo!(03 of25)
As global temperatures rise this century, sea levels are also expected to increase. South Florida may be hit particularly hard.\n\nIf greenhouse gas emissions are not reduced, global sea levels could rise over three feet by 2100, with a six foot rise possible. The U.S. Select Committee on Energy Independence and Global Warming notes:\n
This threatens to submerge Florida\'s coastal communities and economies since roughly 9 percent of the state is within 5 feet of the existing sea level. Rising sea level also threatens the beaches, wetlands, and mangrove forests that surround the state.\n\nUniversity of Florida professor Jack Putz said in 2008, \"People have a hard time accepting that this is happening here,\" reported the Tampa Bay Times. Seeing dead palm trees and other impacts \"brings a global problem right into our own back yard,\" he added.\n\nClick here to see a map showing what different levels of sea level rise would look like for Florida and other states. (credit:Getty)
Cute Baby Polar Bear Videos(04 of25)
A November 2011 study found that polar bear litters are getting smaller as climate change causes sea ice decline. According to World Wildlife Fund, the study \"found that if spring sea ice break-up occurs one month earlier than usual, 40-73 percent of pregnant females could fail to bring cubs to term.\"\n\nThe National Snow and Ice Data Center found that in 2010, Arctic sea ice was at its lowest January level in 30 years.\n\nWith decreased sea ice, polar bears may have greater trouble finding food sources. This could lead to cannibalism, which has already been observed by photographers. Environmental photojournalist Jenny Ross told BBC News in 2011, \"There are increasing numbers of observations of it occurring, particularly on land where polar bears are trapped ashore, completely food-deprived for extended periods of time due to the loss of sea ice as a result of climate change.\" (credit:Getty)
PB&Js(05 of25)
Thanks to a failing peanut crop due to last summer\'s scorching hot weather, there was a shortage of peanuts in supply at the end of 2011. If temperatures continue to rise, a jump in peanut butter prices is just the prelude to what could be in store for the beloved spread. (credit:Alamy)
Chocolate Cravings(06 of25)
A report released by the International Center For Tropical Agriculture warns chocolate could become a luxury item if farmers don\'t adapt to rising temperatures in Ghana and the Ivory Coast, where a majority of the world\'s cocoa is grown.\n\nThe October 2011 report, funded by the Bill and Melinda Gates Foundation, \"calls for increased research into heat and drought resistant crops, and to help transition cocoa farming to new regions that will be suitable for production in the future,\" reported ThinkProgress. (credit:Flickr: John Loo)
Not Sneezing(07 of25)
Bad news for allergy sufferers -- climate change, and specifically warmer temperatures, may bring more pollen and ragweed, according to a 2011 study from the Mount Sinai School of Medicine in New York.\n\nAlong with allergies, a changing climate may be tied to more infectious diseases. According to one study, climate change could affect wild bird migratory patterns, increasing the chances for human flu pandemics. Illnesses like Lyme disease could also become more prominent. (credit:Flickr: mcfarlandmo)
Keg Stands(08 of25)
Famed for producing some of the world\'s best beer, Germany could suffer from a drop in production due to climate change-induced water shortages. Barley and hops can only be grown with water, and using cheaper alternatives like corn isn\'t possible in Germany because of strict regulations about what you can make beer with.\n\nResearch published earlier this year in the journal Nature Climate Change found that \"unless farmers develop more heat-tolerant corn varieties or gradually move corn production from the United States into Canada, frequent heat waves will cause sharp price spikes,\" reported The New York Times. Price spikes for U.S. corn could affect prices of American macrobrews made with an adjunct ingredient like corn. (credit:Flickr: khawkins04)
Valentine's Day Cliches(09 of25)
With higher temperatures expected in northern latitudes in coming decades, the U.K. has begun a program to develop strawberries that will survive in higher temperatures with less water. Since chocolate also may be threatened, could sexy chocolate-covered strawberries, a Valentine\'s Day staple, be endangered?\n\nAccording to The Telegraph, Dr. David Simpson, a scientist with England\'s East Malling Research, said last year, \"Consumer demand for fresh strawberries in the UK has been growing year on year since the early 1990s. The British growers have done a great job of increasing their productivity to satisfy this demand between April and October. The future will be challenging due to the impacts of climate change and the withdrawal of many pesticides but the breeding programme at EMR is using the latest scientific approaches to develop a range of varieties that will meet the needs of our growers for the future.\" (credit:Getty File)
Coffeehouse Snobs(10 of25)
Coffee lovers may want to get that caffeine fix before the treasured drink becomes a rare export. Starbucks raised the issue last year when the company\'s director of sustainability told The Guardian that climate change is threatening the supply chain for the Arabica coffee bean.\n\nStarbucks Sustainability Director Jim Hanna told the paper, \"What we are really seeing as a company as we look 10, 20, 30 years down the road - if conditions continue as they are - is a potentially significant risk to our supply chain, which is the Arabica coffee bean.\" (credit:Flickr: Marc_Smith)
Rudolph (And Donner And Blitzen)(11 of25)
Reindeer, also known as \"caribou\" in North America, could face a difficult future in a warmer climate. According to U.S. News & World Report, \"Russell Graham, associate professor of geosciences and director of the Earth and Mineral Sciences Museum at Penn State University, says global warming will most harm the animals adapted to the coldest environments, primarily those accustomed to life in the Arctic.\"\n\nA 2008 study found that caribou in West Greenland are \"now arriving after peak foraging time, fewer calves are being born and more calves are dying,\" reported ScienceNews. (credit:Flickr: alana sise)
Yummy Pancake Breakfasts(12 of25)
It may be a bit harder to drown your pancakes in maple syrup in the future, studies suggest.\n\nAccording to a 2010 Cornell University study, \"maple syrup production in the Northeast is expected to slightly decline by 2100, and the window for tapping trees will move earlier by about a month.\" Additionally, most maple syrup production south of Pennsylvania \"will likely be lost by 2100 due to lack of freezing.\"\n\nClick here to watch one farmer\'s fight to save New Hampshire\'s sugar maples. (credit:ShutterStock)
Gone Fishin'(13 of25)
According to a 2002 study by the Natural Resources Defense Council and Defenders of Wildlife, a warming planet does not bode well for species that thrive in cold streams. The study found that \"global warming is likely to spur the disappearance of trout and salmon from as much as 18 to 38 percent of their current habitat by the year 2090.\"\n\nA 2011 study published in the Proceedings of the National Academies of Science produced \"models [which] forecast significant declines in trout habitat across the interior western United States in the 21st century,\" reported The New York Times.\n\nThe study claims, \"The decline will have significant socioeconomic consequences as recreational trout fisheries are valued in the hundreds of millions of dollars in the United States alone.\" (credit:Flickr: qmnonic)
NYC's Waterfront Real Estate (14 of25)
According to a 2012 report from New Jersey-based nonprofit Climate Central, thousands of New York City residents may be at risk for severe coastal flooding as a result of climate change.\n\nClimate Central explains, \"the NY metro area hosts the nation\'s highest-density populations vulnerable to sea level rise.\" They argue, \"the funnel shape of New York Harbor has the potential to magnify storm surges already supplemented by sea level rise, threatening widespread areas of New York City.\" (credit:Flickr: wuestenigel)
The Best Part Of July 4th(15 of25)
With droughts and wildfires hitting many parts of the U.S., municipalities from Colorado to Tennessee canceled July 4th public fireworks displays or banned personal fireworks this year, citing the fire hazards they posed.\n\nIn June, a study published in the journal Ecosphere found that almost all of North America will see more wildfires by 2100, reported Reuters. The study\'s lead author, Max Moritz, said, \"In the long run, we found what most fear - increasing fire activity across large areas of the planet.\" (credit:Getty File)
The Non-.com Amazon(16 of25)
Along with deforestation, climate change also poses a serious threat to South America\'s Amazon rainforest.\n\nA 2009 study from the U.K. Met Office found that a global temperature rise of four degrees Celsius above pre-industrial levels would cause 85 percent of the Amazon to die off in the next 100 years. Even a two degree Celsius rise would kill 20 to 40 percent of the rainforest, reported the Guardian.\n\nIn May, The Club of Rome think tank predicted a global average temperatures rise of \"2 degrees Celsius by 2052 and a 2.8 degree rise by 2080,\" reported Reuters. Jorgen Randers, author of the club\'s report, said, \"It is unlikely that governments will pass necessary regulation to force the markets to allocate more money into climate-friendly solutions, and (we) must not assume that markets will work for the benefit of humankind.\"\n\nHe added, \"We are emitting twice as much greenhouse gases every year as are absorbed by the world\'s forests and oceans. This overshoot will worsen and will peak in 2030.\" (credit:Getty)
Island Getaways(17 of25)
As global sea levels rise during the 21st century, low-lying island nations like the Maldives could see their very existence threatened. With a three to six foot sea level rise predicted by 2100, nations like the Maldives could become uninhabitable, explained The New York Times.\n\nMaldives\' former president, Mohamed Nasheed, has been a tireless campaigner for the urgent need for countries to take action against climate change, arguing \"You can\'t pick and choose on science.\" (credit:Flickr: thetravelguru)
Ski Bums(18 of25)
Although seasonal fluctuations occur and El Nino/La Nina weather patterns affect snowfall, global temperature rise may impact conditions for skiers and boarders.\n\n\"The long-term trend is less snow and earlier snowmelt. This means more frustration for snow sport enthusiasts and a negative impact on the snow sports industry,\" writes the Natural Resources Defense Council\'s Theo Spencer.\n\nIn May, a snow-less ski race was held in Aspen, Colorado to \"highlight the effect climate change has on the outdoor recreation industry,\" reported the Associated Press. (credit:Flickr: Klearchos Kapoutsis)
Thanksgiving Dinner Food Comas(19 of25)
A 2010 paper in the journal Food Research International found that climate change may one day affect the cost and quality of traditional Thanksgiving dishes, reported Discovery News.\n\nFuture temperature rises could impact the quality of turkey meat. Additionally, foods like \"pumpkins, sweet potatoes, potatoes, grains [and] green beans ... will be sensitive to water shortages should they arise,\" study author Neville Gregory told Discovery News.\n\nIn fact, common Thanksgiving foods were impacted by weather events in 2011, with shortages and price spikes hitting over the holidays. (credit:Flickr: ilovebutter)
"Lady & The Tramp"-Like Scenes(20 of25)
Scientists at the British Met Office warn that Italy may soon be forced to import the basic ingredients to make pasta because climate change will make it impossible to grow durum wheat domestically. The crop could almost disappear from the country later this century, scientists say. (credit:Flickr: CyboRoZ)
Super Duper Fast Wi-Fi Connection(21 of25)
A 2011 report from the U.K.\'s Department for Environment, Food and Rural Affairs found that climate change could affect certain infrastructure, like wireless internet. The Guardian reports, \"higher temperatures can reduce the range of wireless communications, rainstorms can impact the reliability of the signal, and drier summers and wetter winters may cause greater subsidence, damaging masts and underground cables,\" according to secretary of state for the environment.\n\nThe Guardian notes, \"The government acknowledges that the impact of climate change on telecommunications is not well understood, but the report raises a series of potential risks.\" (credit:Getty)
The Great Smoky Mountains' Smoke(22 of25)
The Great Smoky Mountains have the most annual rainfall in the southeastern U.S., which mostly falls as a light, misty rain, explains OurAmazingPlanet.\n\nA study by a team from NASA\'s Precipitation Measurement Missions found that \"light rainfall is the dominant form of precipitation in the region, accounting for 50 to 60 percent of a year\'s total, governing the regional water cycle.\" \n\nOurAmazingPlanet notes: \n
The results suggest the area may be more susceptible to climate change than thought; as temperatures rise, more of the fine droplets from light rain will evaporate in the air and fail to reach the ground. Lower elevations will have to contend with not only higher temperatures, but less cloud cover.(credit:Flickr: scmikeburton)
California Beach Bums(23 of25)
Along the California coast, beach communities are finding that it may be impossible to stop coastal erosion as global sea levels rise. \n\nAccording to AP, David Revell, a senior coastal scientist at ESA PWA, acknowledged the relentless power of the sea, saying, \"I like to think of it as getting out of the way gracefully.\"\n\nA report released in June by the Natural Resources Defense Council found that West Coast ocean levels will rise several inches in the next few decades. Sea levels along the California coast are expected to be six inches higher by 2030 and three feet higher by the end of the century.\n\nDespite the risks, another recent NRDC study found that California is one of several states with the best plans to deal with the effects of climate change. (credit:Flickr: bdearth)
Repeats Of The Titanic(24 of25)
2012 could be a record year for the extent of Arctic sea ice at its yearly summer minimum. Walt Meier, a research scientist at the U.S. National Snow and Ice Data Center, said that with recent satellite observations, \"It definitely portends a low-ice year, whether it means it will go below 2007 (the record minimum in September), it is too early to tell,\" reported LiveScience.\n\nAs sea ice declines in the Arctic, countries are anticipating a competition for control of shipping lanes and mineral extraction in the region.\n\nIn Antarctica, research from the United States\' Palmer Station on the Antarctic Peninsula has found that \"87 percent of the peninsula\'s land-bound glaciers are in retreat,\" reported OurAmazingPlanet.\n\nDecreasing sea ice levels were also addressed in a recent spoof of Shell\'s plans to drill for oil in the Arctic this summer. (credit:ARCTICREADY.COM)
Crazy Sugar Highs(25 of25)
Climate change has already impacted sugarcane production in Indonesia. \n\nIn late 2011, the chairman of the Indonesian Sugarcane Farmers Association said, \"sugarcane production decreased by up to 30 percent in 2011 due to climate change that has occurred since 2009.\" \n (credit:ShutterStock)
The Earth From Above
Lake Nasser(01 of11)
Egypt\'s Lake Nasser was photographed in January 2005 from the International Space Station. (credit:NASA)
Sahara Desert(02 of11)
Tassili n\'Ajjer National Park, part of the Sahara Desert, has a bone-dry climate with scant rainfall, yet it doesn\'t blend in with Saharan dunes. Instead, the rocky plateau rises above the surrounding sand seas. This image from 2000 was made from multiple observations by the Landsat 7 satellite, using a combination of infrared, near-infrared and visible light to better distinguish among the park\'s various rock types. (credit:NASA)
Hydrogen Sulfide and Dust Plumes on Namibia's Coast(03 of11)
Cloudless skies allowed a clear view of dust and hydrogen sulfide plumes along the coast of Namibia in early August 2010. Multiple dust plumes blow off the coast toward the ocean, most or all of them probably arising from stream beds. Unlike the reddish-tan sands comprising the dunes directly south of the Kuiseb River, the stream-channel sediments are lighter in color. Wind frequently pushes dust plumes seaward along the Namibian coast. (credit:NASA)
Islands of Four Mountains(04 of11)
The snow-capped volcanoes composing the Islands of the Four Mountains in Alaska\'s Aleutian Island chain look suspiciously like alien worlds in this August 2010 image from the ASTER camera aboard NASA\'s orbiting Terra satellite. (credit:NASA)
Sarychev Volcano(05 of11)
Astronauts at the International Space Station captured this striking view of the Sarychev volcano on Russia\'s Kuril Islands in an early stage of eruption on June 12, 2009. Sarychev Peak is one of the most active volcanoes in the Kuril Islands chain. (credit:NASA)
Arctic Eclipse(06 of11)
NASA\'s Terra satellite was rounding the top of the globe -- making its way from the eastern tip of Siberia and across the Arctic Ocean toward northwest Russia -- when it captured this unique view of a total solar eclipse on Aug. 1, 2008. In the area shown in the image, the sun was obscured for about two minutes. As Earth rotated, the shadow moved southeast across the surface. At the same time, the satellite crossed the Arctic with its path nearly perpendicular to the eclipse.\n (credit:NASA)
Fargo(07 of11)
The Advanced Land Imager on NASA\'s Earth Observing-1 satellite shows a snowy blanket over Fargo, N.D., on Dec. 12. (credit:NASA)
Island Beauty(08 of11)
The south end of Eleuthera Island in the Bahamas shimmers in turquoise waters in this 2002 photo from the International Space Station. (credit:NASA)
Massive Sandstorm(09 of11)
A massive sandstorm sweeps over Qatar as it races south toward southeastern Saudi Arabia and the United Arab Emirates on Feb. 15, 2004. A major upper-level, low-pressure system over southwestern Asia led to a series of storms sweeping through the area. The crew of the International Space Station captured this image with a digital camera using a 50-millimeter lens. (credit:NASA)
Lake Naivasha, Kenya(10 of11)
Flowers grow year round in sun-drenched Kenya, and nowhere are they more plentiful than Lake Naivasha, shown here. In this view from space, bright white squares mix with fields of green, tan and purple along the shores of the lake. Sunlight glints off the long rows of glass greenhouses, turning them silvery blue and white. Fallow fields are tan and pink, while growing plants turn the ground bright green. Roses, lilies and carnations are the most common flowers grown in the greenhouses and fields scattered around the lake. (credit:GSFC / METI / ERSDAC / JAROS / NASA)
Cumulonimbus Cloud Over Africa(11 of11)
High above the African continent, tall, dense cumulonimbus clouds, meaning \"cloud heap\" in Latin, are the result of atmospheric instability. The clouds can form alone, in clusters or along a cold front in a squall line. The high energy of these storms is associated with heavy precipitation, lightning, high wind speeds and tornadoes. (credit:NASA)