科學家預測南極大型冰川消失的速率將會變得更快

原文網址：www.sciencedaily.com/releases/2016/05/160518133819.htm

Scientists predict extensive ice loss from huge Antarctic glacier

科學家預測南極大型冰川消失的速率將會變得更快

Current rates of climate change could trigger instability in a major Antarctic glacier, ultimately leading to more than 2m of sea-level rise.

現行的氣候變遷速率會造成南極的一條主要冰川變得相當不穩定，最終可能導致海面上升超過2公尺。

This is the conclusion of a new study looking at the future of Totten Glacier, a significant glacier in Antarctica. Totten Glacier drains one of the world's largest areas of ice, on the East Antarctic Ice Sheet (EAIS).

對托滕冰川(Totten Glacier)的未來命運進行的新研究導出了上述結論。托滕冰川是一條位於南極洲的大型冰川，它流經全世界最大的冰原之一—東南極冰原( East Antarctic Ice Sheet, EAIS)。

By studying the history of Totten's advances and retreats, researchers have discovered that if climate change continues unabated, the glacier could cross a critical threshold within the next century, entering an irreversible period of very rapid retreat.

研究人員藉由探討托滕冰川前進和後退的歷史，發現如果氣候變遷在未來仍未減緩，托滕冰川可能會在下個世紀內跨過一道臨界值，而進入再也無法挽回的極端快速消融期。

This would cause it to withdraw up to 300 kilometres inland in the following centuries and release vast quantities of water, contributing up to 2.9 metres to global sea-level rise.

這會造成托滕冰川在下個世紀往內陸退縮長達300公里並且融化出大量的淡水，導致全球海平面上升2.9公尺之多。

The EAIS is currently thought to be relatively stable in the face of global warming compared with the much smaller ice sheet in West Antarctica, but Totten Glacier is bucking the trend by losing substantial amounts of ice. The new research reveals that Totten Glacier may be even more vulnerable than previously thought.

在面臨全球暖化的威脅時，相較位在西南極面積小了許多的冰原來說，目前認為東南極冰原是較為穩定的地區。然而與此趨勢相反，托滕冰川其實已經流失了大量冰雪。新研究顯示跟我們過往認為的相比，托滕冰川實際上可能更加脆弱。

The study, by scientists from Imperial College London and institutions in Australia, the US, and New Zealand is published today in Nature. Last year, the team discovered that there is currently warm water circulating underneath a floating portion of the glacier that is causing more melting than might have been expected.

這篇今日刊登於期刊《自然》(Nature)的新研究由倫敦帝國學院以及澳洲、美國和紐西蘭學術機構的科學家進行。研究團隊去年發現在冰河漂浮於海面的部分的下方，目前於此循環的暖水融化冰河的能力可能比我們預期中還要超出許多。

Their new research looks at the underlying geology of the glacier and reveals that if it retreats another 100-150 km, its front will be sitting on an unstable bed and this could trigger a period of rapid retreat for the glacier. This would cause it to withdraw nearly 300 km inland from its current front at the coast.

他們的新研究著眼於托滕冰河之下的地質，並且發現如果冰河再繼續往後消退100至150公里，則它的前緣將會落在一個不穩定岩盤之上，這可能造成冰河進入一段快速消融期。結果將會使目前位於海岸附近的冰河前緣往內陸退縮將近300公里。

Retreating the full 300 km inland may take several hundred years, according to co-author Professor Martin Siegert, Co-Director of the Grantham Institute at Imperial College London. However, once the glacier crosses the threshold into the unstable region, the melting will be unstoppable -- at least until it has retreated to the point where the geology becomes more stable again.

根據倫敦帝國學院葛拉森研究所的共同作者 Martin Siegert教授所言，托滕冰河要往內陸後退整整300公里大概需要數百年的時間。然而，一旦冰河跨越臨界值而進入不穩定狀態，融化的趨勢就會變得銳不可擋—至少要等到冰河後退至地質再次穩定的地區為止。

"The evidence coming together is painting a picture of East Antarctica being much more vulnerable to a warming environment than we thought," he said. "This is something we should worry about. Totten Glacier is losing ice now, and the warm ocean water that is causing this loss has the potential to also push the glacier back to an unstable place."

「我們結合所有證據描繪出來的圖像顯示，在日趨暖化的環境下南極大陸東部跟我們過往認知中相比，實際上更為脆弱。」他說。「這確實是件我們應該要憂心的事情。托滕冰河的冰雪正不斷流失，而身為罪魁禍首的溫暖海水還可能會將冰河往後推至不穩定的環境。」

"Totten Glacier is only one outlet for the ice of the East Antarctic Ice Sheet, but it could have a huge impact. The East Antarctic Ice Sheet is by far the largest mass of ice on Earth, so any small changes have a big influence globally."

「雖然托滕冰河不過是東南極冰原往海洋流動的管道之一，但它仍可能會造成重大影響。東南極冰原身為當今地球上最大的冰層，任何一點小小的變動都可能對全世界造成巨大的衝擊。」

To uncover the history of Totten Glacier's movements, the team looked at the sedimentary rocks below the glacier using airborne geophysical surveys. From the geological record, influenced by the erosion by ice above, they were able to understand the history of the glacier stretching back millions of years.

為了瞭解托滕冰河移動的歷史，研究團隊利用空中地球物理探測來探測冰河下方的沉積岩。這些地質紀錄會受上方冰河侵蝕作用影響，藉此他們可以得知冰河數百萬年之前的歷史。

They found that the glacier has retreated more quickly over certain 'unstable' regions in the past. Based on this evidence, the scientists believe that when the glacier hits these regions again we will see the same pattern of rapid retreat.

他們發現過去冰河在經過某些不穩定地區時，冰河消融的速度會變得更快。科學家根據這些證據，認為當冰河未來再次經過這種地帶時，我們同樣會看見冰河進入這種快速倒退的模式。

引用自：Imperial College London. "Scientists predict extensive ice loss from huge Antarctic glacier." ScienceDaily. ScienceDaily, 18 May 2016. .