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2014年2月11日火曜日

気になった一文集(English ver. No. 19)

The impact of this change is small but not negligible: without the reductions in CFC emissions, temperatures today could have been almost 0.1 °C warmer than they actually are.
この変化の影響は小さいが無視できない程度である。もしCFC(フロンガス類)の排出の減少がなければ、今日の温度はおおよそ0.1℃現在の値よりも高くなっていたに違いない。

This simple analysis supports the idea that the reductions in CFC emissions that were enforced by the Montreal Protocol contributed to the warming hiatus of the past 15 years. However, it also suggests that this is unlikely to be the whole story. To fully account for the lack of warming that would have been expected between 1998 and 2012, the reduction in radiative forcing from CFCs would have had to be much stronger.
この単純な分析は「モントリオール議定書によって規制されたCFCの排出量の低下が過去15年間の温暖化のハイエタスの原因である」という考えを支持している。しかしながら、それが全体をうまく説明する可能性が低いことも示している。1998年から2012年の間の温暖化の不足をすべて説明するには、CFCsからの放射強制力の減少がもっと大きくなければならない。

The untidy conclusion is that the explanation of the much-discussed warming hiatus over the past decade and a half is unlikely to be a simple single issue. Various neglected effects that are difficult to capture adequately through deterministic linear trend models — such as stratospheric volcanic aerosols, deep ocean heat uptake, the unusually strong solar minimum and internal climate variability — are all likely to have played a role.
乱雑な結論は「広く議論されている過去15年間の温暖化のハイエタスの原因は一つの単純な問題には帰結できなさそう」ということである。決定論的な線形近似モデルの中では適切に再現することが難しい、様々な無視されている効果(例えば成層圏の火山性エアロゾル、深海の熱吸収、例になく大きい太陽活動極小、内部気候変動など)がすべて役割を負っている可能性が高いためである。

Although Estrada and colleagues’ proposal does not seem to explain the entire hiatus, their findings once again confirm that the warming slow-down does not significantly affect the attribution of most of the warming since about 1960 to human influence.
Estradaほかの提案はハイエタス全体を説明することは難しそうだが、彼らの発見は再度「温暖化の停滞が約1960年以降の温暖化の大部分が人類の影響によるものである」という事実を確たるものにしてくれる。

Breaks in trendsNature Geoscience 6, 992–993 (2013)

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“Ocean acidification research is still in its infancy but we already know enough to act”, Osborn said. He further highlighted the critical need to bring international attention to this “hidden” consequence of increasing CO2 emissions. Despite the potential serious impacts of rising CO2 emissions on our oceans, they have been largely absent from the UN climate discussions.

Ocean acidification is “the other CO2 problem” and an excellent additional reason to reduce human induced CO2 emissions to the atmosphere.

The other CO2 problem – IAEA highlights ocean acidification at climate change conferenceInternational Atomic Energy Agency (18 November 2013)

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...despite technical advances and the considerable efforts of climate scientists, the range of climate sensitivities estimated by the Intergovernmental Panel on Climate Change (IPCC) using computer models has not narrowed since 1990, and remains at roughly 1.5–4.5 °C.

The researchers came up with three crucial findings. First, they observed that differences in mixing strength explained about half of the spread of climate sensitivities estimated by the models. Second, they found that changes in mixing strength depend on the mixing strength in simulations of the current climate, which was used as the initial value in the experiments. And third, they conclude that estimates of current mixing strength based on observations imply a climate sensitivity of more than 3 °C, which is in the upper half of the IPCC’s range of estimates.

 「Clouds of uncertaintyNature 505 (2 JANUARY 2014)

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It is estimated that the fresher AABW can account for about half of the total Antarctic ice-mass loss (45 ± 26 %). Although the Southern Ocean and AABW occupy a relatively small fraction of the global ocean, the warming of the water column surrounding Antarctica could account for about 18 ± 8 % of the ~180 TW heat gain in the climate system over the late twentieth century; resulting in a rise of the Southern Ocean’s sea level of 1–2 mm per year. 
より淡水化するAABW(南極底層水)ですべての南極の氷の全質量損失(45 ± 26 %)のおよそ半分を説明できると推定されている。南大洋とAABWは全球の海の比較的わずかな分しか占めていないにもかかわらず、南極周辺の水柱の温暖化は21世紀末を通して気候システムが獲得した180 TWの熱の18 ± 8 %に相当する。その結果、南大洋の海水準は年間1–2 mmで上昇している。

Surface waters around Antarctica are also freshening and it would seem likely that a signif cant fraction of the Antarctic melt ends up in these waters. Fresher surface waters are lighter and further isolate sea-ice from the warmer ocean below, and may help explain observed increases in Antarctic sea-ice cover.
南極周辺の表層水もまた淡水化しており、南極の融け水のかなりの部分がこうした水になっている可能性が高い。より塩分の少ない水は軽く、海氷を下の暖かい海水から隔離する働きがあるため、観測されている南極の海氷範囲の拡大を説明する手助けとなるかもしれない。

Deep ocean fresheningNature Climate Change 3, 864–865 (2013)

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On some level, most people understand the difference between climate and weather. Climate is the context: the accumulation of temperatures and precipitation trends that vary depending on location and season. Weather is what we experience, and extremes are part of the package. 
ある程度、大半の人は気候と気象の違いを理解している。気候は文脈であり、場所や季節によって異なる気温や降水の傾向の蓄積である。気象は我々が日々経験するものであり、異常気象はその中の一部である。

Despite such assessments, however, people continually confound weather and climate in the heat — or cold — of the moment. Confusion seems unavoidable.
しかしながら、そうした客観的評価にも関わらず、人はつかの間の暑さや寒さの中で気象と気候の違いを繰り返し混同している。混乱はある意味避けがたいものかもしれない。

At first blush, the global-warming ‘hiatus’ runs counter to the warming projected by climate models…Ultimately, the hiatus has provided an opportunity to better understand both the climate system and climate models. One lesson is that the climate, like day-to-day weather, has its ups and downs. Another is that the average global temperature — although a useful indicator — is not the only measure of how the climate changes.
一見、地球温暖化の’ハイエタス(一時中断)’は気候モデルが予測する温暖化に相反するように思われる。(中略)究極的には、ハイエタスはよりよく気候システムと気候モデルを理解する機会を与えてくれる。一つの教訓は気候は日々の気象と同じく、上り下がりするということ。もう一つの教訓は平均的な地球の温度だけが(とても便利な指標だけれど)気候変化の計り方の唯一の手段ではないということである。

Cool heads neededNature 505, 261–262 (16 January 2014).

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successful papers may provide compelling support for something that had been a mere suspicion, or they may present an entirely novel interpretation of existing data — or something that falls between those two, in terms of novelty and robustness. The essence, for us, is that the paper makes a difference to the way our readers think about Earth or planetary systems.

The paper trailNature Geoscience 7, 77 (Feb 2014)