Sensitivity Of West Antarctic Ice Sheet To 2C Warming

随着地球变暖，全球平均海平面正在上升。自1900年以来，海平面上升了约20厘米，最初是由于水温升高和高山冰川融化造成的。然而，近年来，格陵兰岛和南极洲大冰原的融化显著增加，陆地冰（冰川和冰原）的损失现在是全球平均海平面的最大贡献者。极地冰盖相当于海平面几十米，但对温室气体排放增加的反应缓慢（即比全球气温变暖慢）。因此，随着气温每升高一度，人类社会将面临未来数百年乃至数千年海平面上升的长期承诺。这是真的，即使明天就停止全球排放，未来变暖将保持在2摄氏度以下（2015年《巴黎协定》设定的目标）。南极西部冰原（WAIS）拥有相当于4.3米的海平面，是今天观测到的南极洲质量损失最大的部分。这激发了一个国际联盟的形成，从罗斯海（南极洲）的两个钻探点回收沉积物，以回答以下问题：“WAIS对2摄氏度变暖的敏感性是什么？”本提案展示了英国社区如何通过结合我们在生成综合数据和建模方法方面的独特专业知识来最好地贡献和领导回答这个关键问题，以解决三个目标：(1)在过去的温暖时期，WAIS的配置是什么？(2)在过去的地质历史中，西秦岭是如何后退和前进的？(3)随着时间的推移，南极景观的变化如何影响冰的动力学？我们将使用先进的实验室方法来确定沉积物的化学指纹，以及这与沉积物在大陆上的来源、最后一次暴露的时间、沉积物离冰盖边缘的距离以及在什么环境条件下沉积的关系。通过在数值模型中使用这些信息，我们将克服一个长期存在的限制，即用于预测未来的模型经常提供与过去冰盖结构相反的结果。我们将使用一系列模型，从简单的冰盖模型到先进的冰盖和气候耦合模型，以更准确地描绘与海洋变暖、大气变暖和陆地地形变化有关的过去WAIS动力学和机制，并与冰芯和海洋沉积物岩芯的观测结果相一致。

As our planet is warming, global mean sea level is rising. Since the year 1900 this rise in sea level has been ~ 20 cm, initially due to the expansion of water under warmer temperatures and melting of mountain glaciers. However, over recent years the melting of the large ice sheets on Greenland and Antarctica has increased significantly, and loss of land ice (glaciers and ice sheets) is now the largest contributor to global mean sea level. The polar ice sheets hold many tens of metres of sea level equivalent, but are slow to respond to enhanced greenhouse gas emissions (i.e. slower than global temperatures). With every degree of warming, society is hence facing a long-term commitment in sea level rise for centuries and millennia into the future. This is true, even if global emissions would be halted tomorrow, and future warming would be kept below 2 degrees C, the target set by the Paris agreement in 2015. The West Antarctic Ice Sheet (WAIS) holds 4.3 m of sea level equivalent and is the part of Antarctica where most mass loss is observed today. This motivated the formation of an international consortium to recover sediments from two drill sites in the Ross Sea (Antarctica) to answer the following question: 'What is the sensitivity of the WAIS to 2C warming'. This proposal presents the case how the UK community could best contribute and lead in answering this critical question by combining our unique expertise in generating combined data and modelling approaches to address three objectives: (1) What was the configuration of the WAIS during past warm periods? (2) How did the WAIS retreat and readvance in the geological past? (3) How do changes in the Antarctic landscape through time affect ice dynamics? We will use advanced laboratory methodologies to determine the chemical fingerprint of sediments and how this relates to where on the continent the sediment came from, when it was last exposed, how close to the ice sheet margin it was deposited and under what environmental conditions. By using this information in numerical models, we will overcome a longstanding limitation that the models used to predict the future are often providing contrasting results on past ice sheet configurations. We will use a hierarchy of models, from simple ice sheet models to advanced coupled ice sheet and climate models to develop a more accurate picture of past WAIS dynamics and mechanisms in relation to ocean warming, atmospheric warming, and changing topography on land, consistent with observations from ice cores and marine sediment cores.