冰河融化使海平面以前所未見的速率上升

原文網址：https://www.media.uzh.ch/en/Press-Releases/2019/Glacier.html

冰河融化使海平面以前所未見的速率上升

格陵蘭與南極洲的冰層，加上世界各處的冰河融化正在讓海平面持續上升。由瑞士蘇黎世大學領導的國際研究團隊發現1961年以來，單就冰河來說已經有9兆噸的冰塊融化，足以讓海平面上升27毫米。

從1961年至2016年全球各區域的冰河對海平面上升的貢獻比例。泡泡的大小對應了全球以及各個區域的冰河在這段期間的總質量變化(單位為Gt，1Gt = 10億噸)。比方說阿拉斯加(ALA)的冰河融化了超過3兆噸，使其成為全球海平面上升的最大來源。東南亞(名稱為ASW的藍色泡泡)的冰河則是唯一質量有增加的。圖片來源：Michael Zemp

從1961年到2016年，全世界總共有超過9兆噸(精確來說為9,625,000,000,000噸)的的冰河融化，讓這段期間的全球海平面上升了27毫米。其中占比最多的是阿拉斯加的冰河，再來則是巴塔哥尼亞的冰原以及北極地區的冰河。歐洲阿爾卑斯山、高加索的山地以及紐西蘭的冰河也流失了很大一部份，不過這些地區冰河覆蓋的面積相對來說較小，使它們對全球海平面上升的貢獻並不大。

結合實地觀察和衛星測量

蘇黎世大學領導的國際研究團隊進行這項研究時，結合了實地進行的冰河觀測，以及利用衛星的大地測量。後者是以數位化的方法測量地球表面，藉此得出冰層在不同時間的厚度數據。研究人員結合世界冰河監測組織全世界的觀測網，以及他們自身的衛星數據，而彙整出十分詳盡的資料庫，使他們重建出世界各地超過19,000條冰河的厚度如何變化。

「結合這兩種觀測方法，得出十分全面的新資料庫之後，我們可以估計從1960年代開始，全球山區每年有多少冰川融化。」主持這項研究的Michael Zemp加以解釋。「實地進行的冰河學測量提供了年度變化數據；而衛星測量則可以讓我們算出數年到數十年間，整體來說有多少冰川融化了。」

每年融化的冰川總共有3350億噸

過去30年全球冰河的流失速度快速攀升，現今每年融化的冰河總共有3350億噸，相當於海平面每年會因此而上升將近1毫米。冰河學家Zemp表示：「全球來說，光是一年融化的冰川體積，就相當於整個歐洲阿爾卑斯山含有的冰的三倍左右！」現今全球海平面的上升有百分之25到30需歸因於冰河融化，這跟格陵蘭冰層的融化量差不多，而且更勝於南極。

Melting glaciers causing sea levels to rise at ever greater rates

Melting ice sheets in Greenland and the Antarctic as well as ice melt from glaciers all over the world are causing sea levels to rise. Glaciers alone lost more than 9,000 billion tons of ice since 1961, raising water levels by 27 millimeters, an international research team under the lead of UZH have now found.

Glaciers have lost more than 9,000 billion tons (that is 9 625 000 000 000 tons) of ice between 1961 and 2016, which has resulted in global sea levels increasing by 27 millimeters in this period. The largest contributors were glaciers in Alaska, followed by the melting ice fields in Patagonia and glaciers in the Arctic regions. Glaciers in the European Alps, the Caucasus mountain range and New Zealand were also subject to significant ice loss; however, due to their relatively small glacierized areas they played only a minor role when it comes to the rising global sea levels.

Combination of field observations and satellite measurements

For the new study, the international research team led by UZH combined glaciological field observations with geodetic satellite measurements. The latter digitally measure the surface of the Earth, providing data on ice thickness changes at different points in time. The researchers were thus able to reconstruct changes in the ice thickness of more than 19,000 glaciers worldwide. This was also possible thanks to the comprehensive database compiled by the World Glacier Monitoring Service from its worldwide network of observers, to which the researchers added their own satellite analyses.

“By combining these two measurement methods and having the new comprehensive dataset, we can estimate how much ice has been lost each year in all mountain regions since the 1960s,” explains Michael Zemp, who led the study. “The glaciological measurements made in the field provide the annual fluctuations, while the satellite data allows us to determine overall ice loss over several years or decades.”

335 billion tons of ice lost each year

The global mass loss of glacier ice has increased significantly in the last 30 years and currently amounts to 335 billion tons of lost ice each year. This corresponds to an increase in sea levels of almost 1 millimeter per year. “Globally, we lose about three times the ice volume stored in the entirety of the European Alps – every single year!” says glaciologist Zemp. The melted ice of glaciers therefore accounts for 25 to 30 percent of the current increase in global sea levels. This ice loss of all glaciers roughly corresponds to the mass loss of Greenland’s Ice Sheet, and clearly exceeds that of the Antarctic.

原始論文：Zemp, M., Huss, M., Thibert, E., Eckert, N., McNabb, R., Huber, J., Barandun, M., Machguth, H., Nussbaumer, S.U., Gärtner-Roer, I., Thomson, L., Paul, F., Maussion, F., Kutuzov, S., and Cogley, J.G. Global glacier mass changes and their contributions to sea-level rise from 1961 to 2016. Nature, 2019 DOI: 10.1038/s41586-019-1071-0

引用自：University of Zurich. "Melting glaciers causing sea levels to rise at ever greater rates."