Investigating the climate feedbacks that will determine the fate of the Greenland ice sheet

海平面变化是由温室气体排放引起的气候变化可能造成的最广泛和最严重的后果之一。自1993年以来，格陵兰和南极洲极地冰盖融化对海平面变化的贡献已经使全球海平面上升了约20毫米，预计这一速度在21世纪还将增长。冰质量损失是海平面变化预算中最不确定的部分，很大程度上是因为气候和冰盖模型不能很好地协同工作的事实，严重限制了模拟大冰盖如何与气候变化相互作用的科学。这个项目提议使用我们新的和独特的建模能力来获得对大气和冰盖相互作用方式的新理解。该项目将以格陵兰冰盖为重点，调查大气、海洋和陆地表面物理，这些物理因素决定了冰面上大范围地表条件变化的敏感性，以及冰层范围和高度的变化如何对当地和区域气候和大气环流产生反馈。对未来一个世纪的区域和全球气候模型的研究表明，在给定的气候变化水平下，对冰层表面有多少会融化冰的预测可能会因两个或更多的因素而异。虽然人们已经意识到，由于融化而导致的表面变暖是预测格陵兰百年质量损失速度的关键部分，但现在看来，由于冰盖形状的变化而导致的降雪变化可能也同样重要。在这些大范围的反馈中，有几个相互作用的大气、雪面和冰流过程，但对这些现象的研究却很少。海洋温度在多大程度上以及以何种方式控制着外流冰川的崩解速度，也是一个重要的未知因素。该项目将使用最先进的模型，用于做出英国的全球气候预测，并与格陵兰冰盖的动力学模型交互耦合。一系列实验将研究气候-冰相互作用的机制，它们与区域气候系统的联系，以及它们对格陵兰冰盖的长期未来意味着什么。同时，观测数据(通过遥感和现场获得)将用于验证模型的能力和改进其物理参数。

Sea level change is one of the most widely recognised and zoompotentially serious consequences of climate change due to emissions of greenhouse gases. The contribution to sea level change from melting the polar ice sheets on Greenland and Antarctica has already raised global sea levels by around 20mm since 1993, and this rate is expected to grow over the 21st century. Ice mass loss is the most uncertain part of the sea level change budget, largely because the science of modelling how large ice sheets interact with a changing climate has been severely limited by the fact that climate and ice sheet models do not work well together.This project proposes to use our new and unique modelling capabilities to gain new understanding of the ways in which the atmosphere and ice sheets interact. Focusing on the Greenland ice sheet, this project will investigate the atmospheric, ocean and land surface physics that determine the sensitivity of changing large-scale surface conditions on the ice, and how changes in ice extent and height feedback on both local and regional climate and atmospheric circulation. Studies with regional and global climate models for the coming century have shown that predictions of how much of the surface of the ice will melt ice for a given level of climate change can vary by factor of two or more. And whilst it has been appreciated for some time that warming of the surface due to its reduction in altitude as it melts is a crucial part of predicting the centennial rate of mass loss from Greenland, it now seems likely that changes in snowfall due to the changing shape of the ice sheet may be just as important. There are several interacting atmospheric, snow surface and ice flow processes involved in these large-scale feedbacks, and yet little research into the phenomena. How much, and in what way, ocean temperatures govern the calving rates of outflow glacier is also an important unknown. This project will use a state-of-the-art model, used to make the UK's global climate projections, interactively coupled to a dynamical model of the Greenland ice sheet. A series of experiments will investigate the mechanisms of climate-ice interactions, their links to the regional climate system and what they imply for the long-term future of the Greenland ice sheet. In parallel, observational data (obtained via remote sensing and in situ) will be used to both verify the model's capabilities and improve its physical parameterisations.