West Antarctic Ice Sheet retreat in the context of ENSO variability

卫星观测显示，南极洲西部的冰消失率变化很快，但其原因尚不确定，需要对整个冰-海系统进行建模。最近的研究突出了厄尔尼诺南方涛动(ENSO)对这一对海平面的重要贡献的影响。假设的机制是通过冰架融化的变化，归因于大洋温跃层深度的风力变化，海洋温跃层将较冷的表层水与较暖的绕极深层水分开。为了利用稳定的气候强迫改进对南极西部冰的详细预报，我们提出了一种新的实验，它使用了一个新的同步耦合的冰/海洋模式，该模式可以连续计算冰盖对ENSO驱动的高度可变的海洋强迫的响应。我们试图量化：(1)20世纪南极西部冰川退缩是由ENSO引发的概率；(2)相继发生的强烈拉尼娜事件可能阻止现在发生的退缩；(3)正式将西南极冰盖的变化归因于ENSO或纬向风的人为趋势；以及(4)ENSO和人类活动趋势对用于海岸规划决策的21世纪海平面预测极端的影响。

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.