Collaborative Research: Under what Climate Conditions does the West Antarctic Ice Sheet Collapse?

西南极冰盖（WAIS）的崩溃将使海平面上升约3米（10英尺）。因此，了解WAIS是否会在未来的气候变化下崩溃，以及如果是这样，有多快是至关重要的。了解冰盖如何应对人为气候变化的一种方法是了解它如何应对过去的温暖时期。例如，很可能WAIS在最后一次间冰期（130，000至116，000年前）崩溃。这种崩溃被认为是由冰盖边缘附近的南大洋变暖所解释的，但末次间冰期的气候和可能导致WAIS崩溃的当地海洋条件之间的关系还没有得到很好的理解。 此外，目前还不清楚海洋必须变暖多少才能引发广泛的WAIS撤退。该项目将使用新的建模能力来了解WAIS崩溃所需的气候和冰盖条件。研究结果将有助于更好地估计未来几十年和未来几个世纪海平面大幅上升的可能性。这项工作旨在促进我们对可能导致南极西部冰盖（WAIS）在末次间冰期（LIG）崩溃的气候和冰盖条件的理解，并确定崩溃的条件是否可能在未来几个世纪中得到满足。大多数模拟的LIG南极冰盖依赖于一组有限的规定的海洋热通量，和LIG气候条件和WAIS的行为之间的关系已经探索几乎完全有限或没有冰盖气候耦合。该项目将探索WAIS崩溃的不确定性，通过新的瞬态古气候模拟与社区地球系统模型（CESM 2）耦合到社区冰盖模型（CISM），沿着大量的过去和未来的冰盖模拟实验。这些实验将首次在CESM中包括一个与瞬态气候共同演变的动态南极冰盖，以解释与融水流入海洋、冰架下海洋变暖以及冰盖地形对区域大气环流的影响有关的反馈。该团队还将进行大量的CISM实验，以探索导致WAIS解体的冰盖模型参数和气候边界条件的空间。通过这种方式，该项目将尽可能全面地评估导致WAIS崩溃的相互作用的气候和冰盖条件。这项工作改进了以前的工作，通过使用（1）一个相对高分辨率的冰盖模式，更好地解决接地线动力学，（2）更现实的冰盖-大气和冰盖-海洋耦合，（3）更广泛的可能的气候边界条件，冰架下融化参数，该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

The collapse of the West Antarctic Ice Sheet (WAIS) would raise sea level by about three meters (10 feet). It is therefore critical to understand whether the WAIS will collapse under future climate change, and, if so, how quickly. One way to learn about how the ice sheet will respond to anthropogenic climate change is to understand how it responded to past warm periods. It is very likely, for example, that the WAIS collapsed during the last interglacial period (130,000 to 116,000 years ago). This collapse is thought to be explained by warming of the Southern Ocean near the ice sheet edge, but the relationship between the climate of the last interglacial period and the local ocean conditions that may have led to WAIS collapse is not well understood. In addition, it is unknown how much warmer the ocean must be to trigger widespread WAIS retreat. This project will use new modeling capabilities to understand the combined climate and ice sheet conditions necessary for WAIS collapse. The results will lead to improved estimates of the likelihood of substantial sea-level rise in the next few decades and the coming centuries.This work aims to advance our understanding of the climate and ice sheet conditions that probably led to West Antarctic Ice Sheet (WAIS) collapse during the Last Interglacial (LIG), and to determine whether conditions for collapse are likely to be met in the coming centuries. Most simulations of the LIG Antarctic ice sheet have relied on a limited set of prescribed ocean heat fluxes, and the relationship between LIG climate conditions and the behavior of the WAIS has been explored almost exclusively with limited or no ice sheet-climate coupling. This project will probe WAIS collapse uncertainties through new transient paleoclimate simulations with the Community Earth System Model (CESM2) coupled to the Community Ice Sheet Model (CISM), along with large ensembles of past and future ice-sheet modeling experiments. The experiments will include, for the first time in CESM, a dynamic Antarctic ice sheet co-evolving with a transient climate, to account for feedbacks associated with meltwater fluxes to the ocean, ocean warming under ice shelves, and the influence of ice-sheet topography on the regional atmospheric circulation. The team will also run large ensembles of CISM-only experiments to explore the space of ice-sheet model parameters and climate boundary conditions that lead to WAIS disintegration. In this way, the project will evaluate as fully as possible the interacting climate and ice-sheet conditions that lead to WAIS collapse. This work improves on previous work by using (1) a relatively high-resolution ice-sheet model that better resolves grounding-line dynamics, (2) more realistic ice-sheet-atmosphere and ice-sheet-ocean coupling, and (3) a wider range of possible climate boundary conditions, sub-ice-shelf melting parameters, and ice-sheet physics.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.