West Antarctic Ice Sheet retreat in the context of ENSO variability

卫星观测显示，西南极洲的冰损失率发生了迅速变化，但其原因尚不确定，需要对整个冰-海系统进行建模。最近的研究强调了厄尔Niño南方涛动（ENSO）对海平面这一重要贡献的影响。假设的机制是通过冰架融化的变化，归因于风迫使海洋温跃层深度的变化，将较冷的表层水与较温暖的环极深水分开。为了改进利用稳定气候强迫对南极西部冰的详细预报，我们提出了一种新的冰/海洋同步耦合模式，该模式可以连续计算冰盖对ENSO驱动的高变量海洋强迫的响应。我们寻求量化：(1)20世纪南极西部冰退缩是由ENSO引发的可能性；(2)序贯强La Niña事件阻止目前正在发生的撤退的概率；(3)将南极西部冰盖的变化正式归因于ENSO或纬向风的人为趋势；(4) ENSO和人为趋势对用于沿海规划决策的21世纪海平面极值预测的影响。

Satellite observations show rapid changes in the rate of ice loss from West Antarctica, but attribution of their cause is uncertain and requires modelling of the full ice-ocean system. Recent studies highlight the influence of El Niño Southern Oscillation (ENSO) on this important contribution to sea level. The hypothesised mechanism is through changes in ice-shelf melting, attributed to wind-forced variation in the depth of the oceanic thermocline that separates cooler surface waters from warmer Circumpolar Deep Water beneath. To improve upon detailed forecasts of West Antarctic ice using steady climate forcing, we propose novel experiments using a new synchronously coupled ice/ocean model that can continuously compute the response of the ice sheet to highly-variable oceanic forcing driven by ENSO. We seek to quantify: (1) the probability that 20th Century retreat of West Antarctic ice was triggered by ENSO; (2) the probability that sequential strong La Niña events could halt the retreat happening now; (3) formal attribution of changes in the West Antarctic Ice Sheet to ENSO or anthropogenic trends in zonal winds; and (4) the impact of ENSO and anthropogenic trends on predicted extremes of 21st Century sea level used for coastal planning decisions.