Estimating and reducing the uncertainty in the future behaviour of the Greenland Ice Sheet

海平面上升（SLR）被认为是全球变暖最重要的经济和社会后果之一。冰盖的潜在影响在未来SLR预测中占主导地位，气专委第四次评估报告（第四次评估报告）未能确定冰盖影响的上限，因为对控制其未来行为的过程了解不够。气候将如何演变也很重要。根据气候模式和温室气体（GHG）情景，到2150年，格陵兰冰盖（GrIS）表面物质平衡（SMB）变化的贡献可能在0至4毫米/年的SLR之间。作为参考，第四次评估报告估计，在1993-2003年期间，全球气候信息系统的贡献率为0.21毫米/年。因此，在未来150年内，格陵兰岛的质量损失（不包括冰动力学的任何变化）可能会增加20倍，并可能成为SLR的最大单一来源，但如上所述，预测值的不确定性很大。此外，有人建议，GrIS可以通过> 4.5 ℃的区域温度升高来消除，最终对全球SLR的贡献约为7 m。AR 4的大多数模拟到2100年超过格陵兰岛的温度阈值。气候变化将对冰盖的净质量平衡（即对冰的动态和表面融化效应）产生何种影响，以及气候变化对SLR和淡水生产的可能贡献如何，仍然没有受到充分的限制。该项目的目的是解决造成这种不确定性的几个关键因素，这些不确定性与冰盖将如何应对气候变化以及未来气候的不确定性是由于所用模型中的参数不确定性造成的。此外，我们将把我们的结果和SMB模型纳入下一代哈德利中心AOGCM。

Sea level rise (SLR) is considered to be one of the most economically and socially important consequences of global warming. The potential contribution of the ice sheets dominates uncertainties in projections of future SLR and the fourth assessment report of the IPCC (AR4) was unable to place an upper bound on the contribution of the ice sheets because of an inadequate understanding of processes controlling their future behaviour. Uncertainties in how the climate will evolve are also important. Depending on the climate model and Greenhouse Gas (GHG) scenario the contribution from changes in the surface mass balance (SMB) of the Greenland Ice Sheet (GrIS) could range between ~0 to 4 mm/yr of SLR by 2150. For reference, the AR4 estimates that the GrIS has been contributing 0.21 mm/yr between 1993-2003. Thus, the increase in mass loss (excluding any change in ice dynamics) from Greenland over the next 150 years could go up by a factor of 20 and potentially be the largest single source of SLR but, as mentioned, the uncertainty in predicting the value is large. Further, it has been suggested that the GrIS could be eliminated by a regional temperature rise of > 4.5 degs C, with a final contribution to global SLR of some 7 m. Most simulations from the AR4 exceed this temperature threshold over Greenland by 2100. What impact climate change will have on the net mass balance of the ice sheet (i.e. on both ice dynamic and surface melt effects) and what the likely contribution will be to SLR and freshwater production remain poorly constrained. The aim of this project is to tackle several key components responsible for this uncertainty relating to how the ice sheet will respond to changing climate and what the uncertainties in the future climate are due to parameter uncertainty in the models used. In addition we will incorporate our results and the SMB model into the next generation of Hadley Centre AOGCMs.