Next generation projections of sea level contribution and freshwater export from the Greenland Ice Sheet

冰川和冰盖的冰流失是全球变暖最明显的后果之一。随着地球变暖，我们可以预计冰的流失速度会增加，这些冰最终会进入海洋，导致海平面上升。对海平面上升的准确预测对于世界各地的社会就如何适应沿海地区日益增加的洪水风险做出最佳决定具有巨大的价值。冰的消失还会向海洋释放大量淡水，这可能会影响洋流，特别是在北大西洋，这些洋流对调节我们的气候至关重要。因此，准确预测因冰流失而流入北大西洋的淡水流量，对于评估冰的流失是否足以影响大范围洋流并对全球气候产生影响至关重要。格陵兰冰盖是位于北大西洋的一大块冰，是当前和未来全球海平面上升和流入北大西洋的淡水流量的主要来源。格陵兰的冰以两种方式消失：(I)冰盖表面融化，形成液态淡水，流入海洋；(Ii)由于冰通过被称为潮水冰川的巨大冰川流入海洋；这些冰川产生巨大的冰山，在海洋中融化。虽然我们对冰盖表面融化的预测有合理的信心，但对流入海洋的冰的预测明显落后。迄今为止，对格陵兰岛流入海洋的冰的预测一直受到以下因素的阻碍：(I)缺乏对冰流如何响应气候变化的了解(尽管人们认为最近冰流的增加与海洋温度变暖有关)，以及(Ii)运行未来冰流进入海洋的模型的高昂计算成本。该研究金提出的研究将为这些问题提供新的解决方案，增加人们对格陵兰冰盖预测海平面上升和淡水流量的信心。具体地说，我将开发一个简单的模型，将温暖的水从海洋输送到冰盖边缘，使我们能够快速量化影响冰盖的海水温度。我还将使用过去100年的海洋和气温以及冰川行为的数据集，建立冰川退缩与区域气候变化之间的简单关系。这两项关键进展将使我能够对格陵兰冰盖进行计算机模拟，捕捉到冰流入海洋的过程，以及它在气候变暖时的未来演变。通过这些计算机模拟，我将对未来两个世纪格陵兰冰盖未来海平面上升和淡水输出到北大西洋的预测进行预测，并伴随着相关的不确定性。

Loss of ice from glaciers and ice sheets is one of the most obvious consequences of global warming. As the planet warms we can expect increased rates of ice loss, and this ice ultimately ends up in the ocean causing sea level rise. Accurate projections of sea level rise are hugely valuable for societies around the world to make the best decisions on how to adapt to the increased risk of flooding in coastal areas. Ice loss also releases vast quantities of freshwater into the ocean, which has the potential to affect ocean currents, particularly in the North Atlantic where these currents are critical in regulating our climate. Accurate projections of freshwater flux into the North Atlantic from ice loss are therefore hugely important to assess whether the loss of ice will be sufficient to affect large-scale ocean currents, with implications for global climate.The Greenland Ice Sheet is a vast mass of ice located in the North Atlantic, and is a key current and future source of global sea level rise and freshwater flux into the North Atlantic. Ice in Greenland is lost in two ways: (i) through melting of the ice sheet surface, forming liquid freshwater which flows into the ocean, and (ii) due to the flow of ice into the ocean through vast rivers of ice called tidewater glaciers; these glaciers produce huge icebergs which melt in the ocean. While reasonable confidence exists in our projections of ice sheet surface melting, projections of the flow of ice into the ocean are significantly less advanced.Projections of the flow of ice into the ocean in Greenland have to date been held back by (i) a lack of understanding of how the flow responds to climate change (though it is thought that recent increases in ice flow are related to warmer ocean temperatures), and (ii) the high computational costs of running models of future ice flow into the ocean. The research proposed in this fellowship will offer novel solutions to these problems, increasing confidence in projections of sea level rise and freshwater flux from the Greenland Ice Sheet.Specifically, I will develop a simple model for the transport of warm water from the ocean to the edge of the ice sheet, allowing us to quickly quantify the temperature of the ocean water which affects the ice sheet. I will also use datasets of ocean and air temperature and glacier behaviour from the past 100 years to develop simple relationships between glacier retreat and regional climate change. These two key developments will allow me to run computer simulations of the Greenland Ice Sheet which capture the flow of ice into the ocean, and its future evolution in a warming climate. With these computer simulations I will produce projections, with associated uncertainties, of future sea level rise and freshwater export into the North Atlantic from the Greenland Ice Sheet over the coming two centuries.