The role of atmosphere-ocean-ice interactions in ice loss from Pine Island and Thwaites Glaciers, West Antarctica

南极洲西部冰盖含有200多万立方公里的冰，如果全部融化，海平面将上升3米以上。作为冰盖自然水文循环的一部分，冰在一些冰川中流向海岸，并以冰山的形式消失在海洋中。南极的降雪使冰盖中的冰融化。西南极洲两个最大和流动最快的出口冰川是松岛冰川和斯韦茨冰川，它们共同消耗了西南极洲冰盖的10%。近几十年来，松岛和思韦茨冰川以惊人的速度变薄和退缩，造成了近10%的全球海平面上升。这些冰川上的空气温度几乎从未超过冰点，即使在夏季也是如此，因此它们的退缩并不是大气直接变暖的结果。相反，海洋温度的上升被认为是造成这些变化的原因。松岛湾地区容易受到相对温暖的环极深水的入侵，这种入侵发生在该地区北部的大陆架底部。众所周知，环极深水到达该地区受西南极洲以北海洋上的天气系统的影响，特别是对低压的深度和局部。这项研究将揭示为什么松岛和思韦茨冰川在近几十年来一直在退缩，并预测它们在下一个世纪的演变，并对它们对海平面上升的潜在贡献做出更好的预测。天气模式、洋流、冰川下的融化和冰川本身的退缩之间的联系非常复杂，只能通过在计算机上模拟来理解。因此，我们将开发新的、详细的大气、海洋和冰模型，以模拟松岛湾以北的南大洋环境。我们有过去30年的大量气象数据，这将使我们了解天气模式的变化如何影响环极深水输送到松岛湾。因此，我们将运行1980 - 2010年期间的模型。然而，该地区的卫星图片和海洋学设备从松岛湾海底收集的信息表明，冰川至少从20世纪世纪中期就开始退缩。这可能是上个世纪天气模式变化的结果，但在遥远的南极，我们对这一时期的气象观测很少。因此，我们将利用锁定在冰芯中的化学信号，重建20世纪世纪南大洋这一区域的天气模式。21个国家的国际跨南极科学考察队在南极西部收集了许多冰芯，它们将成为我们重建的基础。松岛冰川和思韦茨冰川在下一个世纪将如何变化是一个极其重要的问题，因为这会对海平面上升产生影响。我们将利用我们在大气环流方面对冰川退缩的了解，对下一个世纪它们的变化作出更好的预测。我们将使用政府间气候变化专门委员会对南极洲西部以北海洋大气变化的预测。他们对不同温室气体增加的大气变化的预测将被使用，并将使我们能够确定环极深水的变化，从而确定下一个世纪冰川的融化。

The West Antarctic Ice Sheet contains over 2 million cubic kilometres of ice, which if it all melting would raise sea level by over 3 metres. As part of the natural hydrological cycle of the ice sheet, ice flows down to the coast in a number of glaciers and is lost to the ocean as ice bergs. Snowfall across the Antarctic then replenishes the ice in the ice sheet. The two largest and fastest flowing West Antarctic outlet glaciers are the Pine Island Glacier and the Thwaites Glacier, which together drain about 10% of the West Antarctic ice sheet. In recent decades the Pine Island and Thwaites Glaciers have thinned and retreated at a remarkable rate, contributing nearly 10% of the observed rise in global sea level. Air temperatures on these glaciers are almost never above freezing, even during the summer months, so their retreat has not been a result of direct warming from the atmosphere. Instead, an increase of ocean temperature is thought to be responsible for the changes. The area of Pine Island Bay is susceptible to intrusions of relatively warm Circumpolar Deep Water that occurs across the floor of the continental shelves to the north of the region. It is known that the arrival of Circumpolar Deep Water to the area is affected by the weather systems over the ocean to the north of West Antarctica, and particularly to the depth and local of depressions. This research will shed light on why the Pine Island and Thwaites Glaciers have been retreating in recent decades and predict their evolution over the next century and produced improved predictions of their potential contribution to sea level rise. The links between weather patterns, ocean currents, melting under the glaciers and the retreat of the glaciers themselves are very complex and can only be understood by simulating them on computers. We will therefore develop new, detailed atmospheric, ocean and ice models to simulate the environment of the Southern Ocean north of the Pine Island bay. We have a great deal of meteorological data for the last 30 years and this will allow us to understand how changes in weather patterns have influenced the delivery of Circumpolar Deep Water to Pine Island Bay. We will therefore run our models for the period 1980 - 2010. However, satellite pictures of the area and information from the ocean floor of Pine Island bay collected by oceanographic equipment suggests that the glaciers have been retreating from at least the middle of the Twentieth Century. This could be a result of changes in the weather patterns during the last century, but in the remote Antarctic we have very few meteorological observations for this period. We will therefore reconstruct the weather patterns across this sector of the Southern Ocean during the Twentieth Century using the chemical signals locked into ice cores. The 21 nation International Trans Antarctic Scientific Expedition has collected many ice cores across West Antarctic and they will form the basis of our reconstruction. How the Pine Island Glacier and the Thwaites Glacier will change over the next century is an extremely important question because of the consequences for sea level rise. We will produce improved predictions of their change during the next century by using our knowledge of glacier retreat in terms of atmospheric circulation. We will use the predictions of atmospheric change across the ocean north of West Antarctica produced by the Intergovernmental Panel on Climate Change. Their predictions of atmospheric change for different increases of greenhouse gases will be used and will allow us to determine changes in Circumpolar Deep Water and therefore melt of the glaciers over the next century.