West Antarctic ice loss influenced by internal climate variability and anthropogenic forcing
West Antarctic ice loss influenced by internal climate variability and anthropogenic forcing
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DOI：
10.1038/s41561-019-0420-9
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发表时间：
2019-09-01
影响因子：
18.3
通讯作者：
Steig, Eric J.
中科院分区：
文献类型：
--
作者：
Holland, Paul R.;Bracegirdle, Thomas J.;Steig, Eric J.
最近南极西部冰盖的冰层融化是由阿蒙森海冰架融化造成的。陆架断裂处的东风异常加强了温暖的绕极深水输入到阿蒙森海大陆架，这产生了大约十年周期的瞬时融化异常。人类活动对这一过程的影响尚未确定。在这里，我们结合观测和气候模型模拟表明，温室气体强迫的增加导致搁架破碎风从20世纪20年代的平均东风转变为今天的近零平均纬向风。强烈的内部气候变化，主要与热带太平洋有关，叠加在这一强迫趋势上。我们推断，阿蒙森海在整个二十世纪经历了十年来的海洋变化，暖异常逐渐变得更加普遍，为持续的冰川融化提供了可信的解释。现有的气候模型预测表明，到2100年，未来强烈的温室气体强迫将产生持续的平均西风陆架破碎风，这表明温暖的海洋异常将进一步加强。在温室气体浓度稳定的情况下，这些风的变化较弱。
Recent ice loss from the West Antarctic Ice Sheet has been caused by ocean melting of ice shelves in the Amundsen Sea. Eastward wind anomalies at the shelf break enhance the import of warm Circumpolar Deep Water onto the Amundsen Sea continental shelf, which creates transient melting anomalies with an approximately decadal period. No anthropogenic influence on this process has been established. Here, we combine observations and climate model simulations to suggest that increased greenhouse gas forcing caused shelf-break winds to transition from mean easterlies in the 1920s to the near-zero mean zonal winds of the present day. Strong internal climate variability, primarily linked to the tropical Pacific, is superimposed on this forced trend. We infer that the Amundsen Sea experienced decadal ocean variability throughout the twentieth century, with warm anomalies gradually becoming more prevalent, offering a credible explanation for the ongoing ice loss. Existing climate model projections show that strong future greenhouse gas forcing creates persistent mean westerly shelf-break winds by 2100, suggesting a further enhancement of warm ocean anomalies. These wind changes are weaker under a scenario in which greenhouse gas concentrations are stabilized.