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

冰川和冰盖的冰损失是全球变暖最明显的后果之一。随着地球变暖，我们可以预期冰的损失率会增加，这些冰最终会流入海洋，导致海平面上升。海平面上升的准确预测对于世界各地的社会做出最佳决策以适应沿海地区日益增加的洪水风险具有巨大价值。冰的流失也会将大量淡水释放到海洋中，这有可能影响洋流，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，准确预测因冰损失而流入北大西洋的淡水流量对于评估冰损失是否足以影响大规模洋流以及对全球气候的影响非常重要。格陵兰冰盖是位于北大西洋的巨大冰块，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关键来源。格陵兰的冰以两种方式消失：（i）通过冰盖表面的融化，形成流入海洋的液态淡水，以及（ii）由于冰通过称为冰川的巨大冰河流入海洋;这些冰川产生巨大的冰山，融化在海洋中。虽然我们对冰盖表面融化的预测有合理的信心，但对冰流入海洋的预测却远远不够先进。迄今为止，对格陵兰冰流入海洋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理解（尽管人们认为最近冰流的增加与海洋温度升高有关），以及（ii）运行未来冰流入海洋的模型的高计算成本。这项研究将为这些问题提供新的解决方案，增加海平面上升和格陵兰冰盖淡水通量预测的信心。具体来说，我将开发一个简单的模型，用于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年的海洋和空气温度以及冰川行为的数据集来建立冰川退缩与区域气候变化之间的简单关系。这两个关键的发展将使我能够运行格陵兰冰盖的计算机模拟，它捕获了冰流入海洋的流动，以及它在气候变暖中的未来演变。通过这些计算机模拟，我将对未来两个世纪海平面上升和格陵兰冰盖向北大西洋淡水输出的不确定性进行预测。

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.