毎日新聞　2007/1/19

温暖化　最悪6.3度　今世紀末時点IPCC予測　懐疑論を否定

　地球温暖化に対する最新の分析や予測を集約した国連の「気候変動に関する政府間パネル(IPCC)」第4次報告書案を、毎日新聞は入手した。地球の平均気温の上昇や氷雪の融解増などから、人間活動による温室効果ガスの排出で温暖化が確実に起きていると強調。温暖化への懐疑論を否定する内容となった。化石燃料に依存した大量消費型の社会が続くと、今世紀末の地球の平均気温は最大で6.3度、海水面は58センチ上昇すると予測。4度の気温上昇でも、約30億人が水不足に直面し、多くの水生生物が絶滅すると警告した。一方で環境配慮型の社会に転換すれば温度上昇は1度、海面上昇も19センチに抑えられると対策の重要性を訴えた。
　海と陸を合わせた地球の現在の平均気温は約15度とされる。
　報告書案は、1906〜2005年の100年間に平均気温は0.56〜0.92度上昇したと分析した。前回(０１年)の第3次報告書の1901〜2000年の上昇幅(0.4〜0.8度)より大きく、1990年代以降の平均気温の上昇傾向が加速したと指摘した。
　また、経済優先や環境配慮型など社会情勢に応じた6種類の設定で今世紀末(2090〜99年)の年平均気温を予測し、20世紀末より１〜６．３度上昇すると試算した。前回の報告書の試算の1.4〜5.8度上昇より幅が広がった。
　気温上昇に伴う海水面の上昇は19〜58センチとの予測になった。幅は前回の9〜88センチの約5分の2になった。海水の酸性化が進むと初めて具体的に示し、サンゴ礁など海洋生態系への影響を懸念した。
　平均気温が3度上昇すれば、アジアで年間700万人以上が洪水の危機に直面し、世界の1億人以上が新たに食糧難に陥る。4度上昇では、5人に1人が洪水の影響を受け、北米では熱波に見舞われる回数が３〜８倍に増加。北極海の氷も35％減少するという。

温暖化対策　「猶予なし」IPCC報告書案　精密分析で立証

　国連の「気候変動に関する政府間パネル(IPCC)」の第4次報告書案は、新たに得られた観測値と精密な分析をもとに、「地球の平均気温の上昇、氷雪の融解の増加などから温暖化は明白」と断定した。世界で起きている現象を見れば、対策を先延ばしにする猶予はないといえる。
　IPCCの報告書は90年、96年、01年に次いで4回目になる。最初の報告書では、人間活動による温暖化説を観測上の限界から明確にはできなかった。96年に「識別可能で人為的な影響が地球の気候に表れていることが示唆される」と初めて人間活動による温暖化を認めた。しかし、その後も産業界や研究者の一部は「温暖化は科学的に証明されていない」と反発し、米国は０１年に温暖化防止のための京都議定書からの離脱を表明した。
　０１年の第3次報告書をまとめてからの6年間、IPCCは約65万年前までにさかのぼる大気の分析や観測網の充実を踏まえ、温暖化が起きていることに確信を深めた。また、二酸化炭素濃度に応じて気温がどの程度変動するかについても見直し、将来の温度上昇の予測精度を向上させた。
　報告書案で示された21世紀末の温度上昇幅は、政策の違いを反映。現在の大量消費型の社会から、環境配慮型に転換すれば、温度上昇は、生態系への大きな悪影響を避けられる１度に抑えられるとした。
　来年から京都議定書に基づいた温室効黒ガスの排出削減への取り組みが先進国で始まる。今回の報告書案は、途上国を含めた全世界に対し、より真剣で確実な温暖化対策の実行を迫っている。

2007-01-21

Experts: Global Warming Will Happen Faster, And Be More Devastating Than Previously Thought
http://freeinternetpress.com/story.php?sid=10198

Global warming is destined to have a far more destructive and earlier impact than previously estimated, the most authoritative report yet produced on climate change will warn next week.
A draft copy of the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, obtained by The Observer, shows the frequency of devastating storms - like the ones that battered Britain last week - will increase dramatically. Sea levels will rise over the century by around half a meter; snow will disappear from all but the highest mountains; deserts will spread; oceans become acidic, leading to the destruction of coral reefs and atolls; and deadly heatwaves will become more prevalent.

The impact will be catastrophic, forcing hundreds of millions of people to flee their devastated homelands, particularly in tropical, low-lying areas, while creating waves of immigrants whose movements will strain the economies of even the most affluent countries.
"The really chilling thing about the IPCC report is that it is the work of several thousand climate experts who have widely differing views about how greenhouse gases will have their effect. Some think they will have a major impact, others a lesser role. Each paragraph of this report was therefore argued over and scrutinized intensely. Only points that were considered indisputable survived this process. This is a very conservative document - that's what makes it so scary," said one senior U.K. climate expert.

Climate concerns are likely to dominate international politics next month. President Bush is to make the issue a part of his state of the union address on Wednesday while the IPCC report's final version is set for release on February 2 in a set of global news conferences.

Although the final wording of the report is still being worked on, the draft indicates that scientists now have their clearest idea so far about future climate changes, as well as about recent events. It points out that:

-- 12 of the past 13 years were the warmest since records began;
-- ocean temperatures have risen at least three kilometres beneath the surface;
-- glaciers, snow cover and permafrost have decreased in both hemispheres;
-- sea levels are rising at the rate of almost 2 millimeters a year;
-- cold days, nights and frost have become rarer while hot days, hot nights and heatwaves have become more frequent.

And the cause is clear, say the authors: "It is very likely that [man-made] greenhouse gas increases caused most of the average temperature increases since the mid-20th century," says the report.

To date, these changes have caused global temperatures to rise by 0.6 Celsius. The most likely outcome of continuing rises in greenhouses gases will be to make the planet a further 3C hotter by 2100, although the report acknowledges that rises of 4.5C to 5C could be experienced. Ice-cap melting, rises in sea levels, flooding, cyclones and storms will be an inevitable consequence.

Past assessments by the IPCC have suggested such scenarios are "likely" to occur this century. Its latest report, based on sophisticated computer models and more detailed observations of snow cover loss, sea level rises and the spread of deserts, is far more robust and confident. Now the panel writes of changes as "extremely likely" and "almost certain".

And in a specific rebuff to sceptics who still argue natural variation in the Sun's output is the real cause of climate change, the panel says mankind's industrial emissions have had five times more effect on the climate than any fluctuations in solar radiation. We are the masters of our own destruction, in short.

There is some comfort, however. The panel believes the Gulf Stream will go on bathing Britain with its warm waters for the next 100 years. Some researchers have said it could be disrupted by cold waters pouring off Greenland's melting ice sheets, plunging western Europe into a mini Ice Age, as depicted in the disaster film "The Day After Tomorrow".

The report reflects climate scientists' growing fears that Earth is nearing the stage when carbon dioxide rises will bring irreversible change to the planet. "We are seeing vast sections of Antarctic ice disappearing at an alarming rate," said climate expert Chris Rapley, in a phone call to The Observer from the Antarctic Peninsula last week. "That means we can expect to see sea levels rise at about a meter a century from now on - and that will have devastating consequences."

However, there is still hope, said Peter Cox of Exeter University. "We are like alcoholics who have got as far as admitting there is a problem. It is a start. Now we have got to start drying out - which means reducing our carbon output."

Intellpuke: Since it was not mentioned it in this article, I am left to assume that a draft report by NOAA scientists reported on this past week isn't yet included in the IPCC's draft report. The U.S. National Oceanic and Atmospheric Administration's report - drafted by a number of scientists in a variety of climate-related fields - found that CO2 levels in the atmosphere in 2006 were much higher than they anticipated and believe that global warming may be affecting the ability of the soil and water on our planet to absorb CO2, thus accounting for the surprising increase of it in Earth's atmosphere.

In just the past few months, climatogoligists, hydrologists and glaciologists from Europe to Greenland to the North American arctic and to Siberia have been surprised by how fast ice is melting around the planet, saying it is melting much faster than even they anticipated. Siberian and North American scientists are also extremely concerned about the rapidity of thawing in huge regions of permafrost around the planet. As those regions thaw, methane gas is being released and the permafrost areas contain millions if not billions of tons of methane than may soon be relased into the atmosphere by the thawing. Methane is even worse in terms of global warming than CO2.

The meltoff of fresh water from all this thawing ice is going into the oceans and seas of the planet, is afftecting Earth's largest ecosystems (or food chains), and there are already studies showing changes in the Gulf Stream the British are counting on to keep their climate temperate.

Thus, it is beginning to look, at least to me, as if these, and other, facets of global warming are not only becoming cumulative, but are also beginning to move at exponential rates. So, when I hear scientists talking about climate effects a century or centuries from now, I am skeptical because I think many of the worst aspects of global warming will impact us - all of us on the planet - in well less than a century. Nothing would please me more than to be wrong about this and look the fool but, if I'm right, scientists working on global warming are in for a few more very big and very discouraging surprises.