新研究提出警告：我們低估了北極暖化的速度
哥本哈根大學和其他機構的研究人員的最新研究成果表示，北極海冰目前的融化速度比過往推估的還快，但是現行的氣候模型卻還沒把過去40年來急速上升的溫度給納入其中。
圖片來源：Getty Images
加拿大、俄羅斯和歐陸中間的北極海目前的溫度上升速度，比研究人員迄今的氣候模型預測結果都還要快。
過去40年來地球的溫度每10年便上升1度，但是白令海和挪威斯瓦爾巴群島周圍的升溫速度甚至還要更快――它們在這段期間每10年就上升了1.5度。
這是發表在《自然―氣候變遷》(Nature Climate Change)的新研究提出來的結論。
哥本哈根大學尼爾斯．波耳研究所(NBI)的教授Jens
Hesselbjerg Christensen是研究人員之一，他說：「我們就北極海的環境因子進行分析之後，結果清楚地顯示我們一直以來都低估了海平面附近的大氣升溫速度，結果便是海冰的消失速度也會超出我們的預期。」
與Christensen合作的有NBI的同僚，以及卑爾根大學、奧斯陸大學、丹麥大氣研究所和澳洲國立大學的研究人員。他們比較了目前北極的氣溫變化以及我們所知發生在過去的氣候波動，像是120,000至11,000年前冰河期時的格陵蘭。
Jens Hesselbjerg Christensen解釋：「目前北極所經歷的突然升溫，我們只有在末次冰河期有觀察到同樣的現象。冰芯的分析結果顯示在那段期間格陵蘭冰層上方的溫度曾經突然飆升過幾次，在40到100年內便上升了10到12度。」
他強調人們還沒有完全體悟北極急速升溫代表的重要性。因此我們必須更加注重北極暖化，更廣泛的來說，也得更加注重減緩全球暖化的速度。
氣候模型應該考慮突然發生的變化
目前為止氣候模型預測北極的溫度會以穩定及緩慢的方式上升。然而，研究人員的分析結果顯示溫度攀升的步調比預期中還要快上許多。
Jens Hesselbjerg Christensen表示：「我們探討了聯合國氣候委員會用來分析並評估的氣候模型。只有以二氧化碳排放量最高為條件的最糟情況下，模擬結果才會接近於從1979年到目前為止，過去這40年來我們測量到的升溫幅度。」
科學家未來應該投注更多心力來模擬北極的快速氣候變遷帶來的後果，這麼一來我們才能創建出更好的模型來準確地預測溫度會如何上升。
Jens Hesselbjerg Christensen表示：「由於夏季月份發生的變化相當快速，因此海冰的消失速度有可能比大多數氣候模型的預測結果還快。我們必須持續地密切監控溫度如何變化，並把正確的氣候變化過程輸入到模型當中。」最後他總結：
「總之，採取必要措施來讓溫室氣體的排放量確實降到巴黎協定的要求，才能保證北極整年都能有海冰覆蓋。」
New study warns: We have
underestimated the pace at which the Arctic is melting
Arctic sea
ice is melting more quickly than once assumed. Today’s climate models have yet
to incorporate the steep rise in temperatures that have occurred over the past
40 years. This, according to a new study by researchers at the University of
Copenhagen and other institutions.
Temperatures in the Arctic Ocean between Canada,
Russia and Europe are warming faster than researchers’ climate models have been
able to predict.
Over the past 40 years, temperatures have risen by
one degree every decade, and even more so over the Barents Sea and around
Norway’s Svalbard archipelago, where they have increased by 1.5 degrees per
decade throughout the period.
This is the conclusion of a new study published in Nature Climate Change.
"Our analyses of Arctic Ocean conditions
demonstrate that we have been clearly underestimating the rate of temperature
increases in the atmosphere nearest to the sea level, which has ultimately
caused sea ice to disappear faster than we had anticipated," explains Jens
Hesselbjerg Christensen, a professor at the University of Copenhagen’s Niels
Bohr Institute (NBI) and one of the study’s researchers.
Together with his NBI colleagues and researchers from
the Universities of Bergen and Oslo, the Danish Metrological Institute and
Australian National University, he compared current temperature changes in the
Arctic with climate fluctuations that we know from, for example, Greenland
during the ice age between 120,000–11,000 years ago.
"The abrupt rise in temperature now being
experienced in the Arctic has only been observed during the last ice age.
During that time, analyses of ice cores revealed that temperatures over the
Greenland Ice Sheet increased several times, between 10 to 12 degrees, over a
40 to 100-year period," explains Jens Hesselbjerg Christensen.
He emphasizes that the significance of the steep rise
in temperature is yet to be fully appreciated. And, that an increased focus on
the Arctic and reduced global warming, more generally, are musts.
Climate models
ought to take abrupt changes into account
Until now, climate models predicted that Arctic
temperatures would increase slowly and in a stable manner. However, the
researchers' analysis demonstrates that these changes are moving along at a
much faster pace than expected.
"We have looked at the climate models analysed
and assessed by the UN Climate Panel. Only those models based on the worst-case
scenario, with the highest carbon dioxide emissions, come close to what our
temperature measurements show over the past 40 years, from 1979 to today,"
says Jens Hesselbjerg Christensen.
In the future, there ought to be more of a focus on
being able to simulate the impact of abrupt climate change on the Arctic. Doing
so will allow us to create better models that can accurately predict
temperature increases:
"Changes are occurring so rapidly during the
summer months that sea ice is likely to disappear faster than most climate
models have ever predicted. We must continue to closely monitor temperature
changes and incorporate the right climate processes into these models,"
says Jens Hesselbjerg Christensen. He concludes:
"Thus, successfully implementing the necessary
reductions in greenhouse gas emissions to meet the Paris Agreement is essential
in order to ensure a sea-ice packed Arctic year-round."
原始論文：Eystein
Jansen, Jens Hesselbjerg Christensen, Trond Dokken, Kerim H. Nisancioglu, Bo M.
Vinther, Emilie Capron, Chuncheng Guo, Mari F. Jensen, Peter L. Langen, Rasmus
A. Pedersen, Shuting Yang, Mats Bentsen, Helle A. Kjær, Henrik Sadatzki,
Evangeline Sessford & Martin Stendel. Past
perspectives on the present era of abrupt Arctic climate change. Nature Climate Change, 2020 DOI: 10.1038/s41558-020-0860-7
引用自：Niels
Bohr Institute, University of Copenhagen. “New study warns: We have
underestimated the pace at which the Arctic is melting.”
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