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。冰盖的潜在贡献在未来SLR预估中的不确定性占主导地位，IPCC第四次评估报告（AR4）无法对冰盖的贡献设定上限，因为对控制冰盖未来行为的过程了解不足。气候将如何演变的不确定性也很重要。根据气候模式和温室气体（GHG）情景，到2150年，格陵兰冰盖（GrIS）表面质量平衡（SMB）变化的贡献可能在~0 ~ 4mm /年的SLR之间。作为参考，AR4估计GrIS在1993-2003年期间贡献了0.21毫米/年。因此，在未来150年里，格陵兰岛的质量损失（不包括冰动力的任何变化）的增加可能会增加20倍，并可能成为SLR的最大单一来源，但如前所述，预测该值的不确定性很大。此外，有人提出，如果区域温度上升1.5℃，就可以消除GrIS，最终将使全球SLR升高约7米。到2100年，AR4的大多数模拟都超过了格陵兰岛的这个温度阈值。气候变化将对冰盖的净质量平衡产生何种影响（即冰动力效应和地表融化效应），以及气候变化对SLR和淡水产量的可能贡献仍知之甚少。该项目的目的是解决造成这种不确定性的几个关键组成部分，这些不确定性涉及冰盖将如何对气候变化作出反应，以及所使用模型中参数不确定性导致的未来气候的不确定性。此外，我们将把我们的结果和中小企业模式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.