Collaborative Research: Testing the Impact of Climate Change on the Greenland Ice Sheet: Combining Past Climate Records with a Coupled Climate and Ice-Sheet Model

该项目旨在了解格陵兰冰盖对过去气候变化的反应，最终目标是改进对其对未来变化反应的预测。研究人员将汇编过去2万年来有关冰盖大小的所有可用数据。他们还将从冰芯和沉积物核心记录中收集关于地表气温、冰的积累率和周围海洋温度的历史数据。气候记录将被用作区域气候和格陵兰冰盖的数值模型的输入，以调查冰盖对气候条件变化的反应。对格陵兰冰盖变化的直接观测只跨越了过去几十年，因此很难确定趋势并将其与自然变化区分开来。海洋和大气变暖在推动格陵兰冰盖消退方面的相对作用也仍然很少受到限制和争论。确定过去格陵兰冰盖对气候变暖的响应可以为冰盖退缩和质量丧失的速度提供重要的界限。最后一次冰川消融(距今两万年到六千年前)为评估大尺度格陵兰冰盖对变化条件的响应提供了一个自然实验，包括大气中二氧化碳含量的上升。1)是什么导致了上一次冰川消融期间冰盖东西边缘和南缘之间的不同行为，这与突然的冰川气候变化有什么关系？2)在最后一次冰川消融期间，大气和海洋变暖在导致冰缘快速退缩方面的相对重要性是什么？3)考虑到大规模、持续的退冰期气候变暖，受地质记录的限制，格陵兰冰盖向海洋输送冰的最大速率是多少？这些速率与冰盖模型模拟相比如何？解决这些问题将1)提供基本的洞察，了解更广泛的格陵兰冰盖在变暖的世界中的行为，2)测试陆地和海洋冰盖边缘环境对变暖的敏感性，以及3)测试可以应用于未来模拟的格陵兰冰盖模型的保真度。研究人员将通过在科普杂志上的讲座和出版物向公众传播科学成果，并通过电影和动画向博物馆传播魔力星球可视化系统。该项目将培训一名博士后和博士后(地质年代学-数据分析和数值建模)，掌握古气候学、冰川学、冰川地质学和古海洋学的多学科方法。本科生将参与这个项目，目标是在地球科学领域招募代表性不足的群体。

This project is aimed at understanding the response of the Greenland Ice Sheet to past climate changes, with the ultimate goal of improving predictions of its response to future change. The investigators will compile all available data on the size of the ice sheet at times in the past 20,000 years. They will also gather data on the history of surface air temperatures, the accumulation rate of ice, and surrounding ocean temperatures from ice- and sediment core records. The climate records will be used as inputs to a numerical model of the regional climate and the Greenland Ice Sheet to investigate the response of the ice sheet to changes in climate conditions. Direct observations of changes in the Greenland Ice Sheet only span the past few decades, making it difficult to identify a trend and distinguish it from natural variability. The relative roles of oceanic and atmospheric warming in driving Greenland Ice Sheet retreat also remain poorly constrained and debated. Ascertaining past Greenland Ice Sheet response to a warming climate can provide important bounds on the rates at which the ice sheet can retreat and lose mass. The last deglaciation (20 to 6 thousand years ago) provides a natural experiment for assessing large-scale Greenland Ice Sheet response to changing conditions including rising atmospheric carbon dioxide.Three fundamental questions will be addressed by this project. 1) What drove the disparate behavior between west-east margins and southern margins of the ice sheet during the last deglaciation and how does this relate to abrupt deglacial climate change? 2) What is the relative importance of atmospheric versus oceanic warming in causing rapid ice margin retreat during the last deglaciation? 3) Given the large, sustained deglacial climate warming, what is the maximum rate that the Greenland Ice Sheet has delivered ice to the ocean as constrained by the geologic record and how do those rates compare with ice-sheet model simulations? Addressing these questions will 1) provide essential insight into how the broader Greenland Ice Sheet behaves in a warming world, 2) test the sensitivity of terrestrial versus marine ice-margin settings to warming, and 3) test the fidelity of a Greenland Ice Sheet model that can be applied to future simulations. The investigators will disseminate scientific results to the public through lectures and publications in popular science magazines, and to museums with movies and animations on the Magic Planet visualization system. The project will train a postdoc and Ph.D. student (geochronology-data analysis and numerical modeling) in a multi-disciplinary approach to paleoclimatology, glaciology, glacial geology, and paleoceanography. Undergraduates will work on the project, with a goal of recruiting under-represented groups in the geosciences.