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

合作研究：在什么气候条件下，南极西部冰盖会崩溃？

• 批准号: 2044965
• 负责人: William Lipscomb
• 金额: $ 42.16万
• 依托单位: University Corporation For Atmospheric Res
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-08-15 至 2024-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2044965&HistoricalAwards=false
• 关键词: Collaborative; Research; Under; what; Climate

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.

南极冰盖（WAIS）的崩溃将使海平面提高约三米（10英尺）。因此，重要的是要了解WAIS是否会在未来的气候变化下崩溃，如果是的话，WIS是否会崩溃。了解冰盖将如何应对人为气候变化的一种方法是了解其对过去温暖时期的反应。例如，很有可能在最后一次冰河间（130,000至116，000年前）倒塌。人们认为，这种崩溃是通过冰盖边缘附近的南大洋的变暖来解释的，但是最后一次冰川间时期的气候与可能导致Wais崩溃的当地海洋状况之间的关系尚不清楚。 此外，尚不清楚海洋要触发广泛的wais撤退必须高多少。该项目将使用新的建模功能来了解WAIS崩溃所需的气候和冰盖条件的综合条件。结果将导致对未来几十年和接下来几个世纪的大量海平面上升的可能性的估计得到改善。这项工作旨在提高我们对可能导致西南极冰盖（WAIS）在最后一次冰川（LIG）中崩溃的气候和冰盖状况的理解，并确定是否有可能崩溃的条件是在未来的几个世纪中遇到的几个世纪。大多数对西南极冰盖的模拟都依赖于有限的规定海洋热通量，并且在LIG气候条件与WAIS的行为之间的关系几乎完全探索了有限或没有冰原气候耦合。该项目将通过与社区冰盖模型（CISM）以及过去和将来的冰层建模实验的大型集合结合的社区地球系统模型（CESM2），通过新的瞬态古气候模拟（CESM2）来探测WAIS崩溃的不确定性。这些实验将首次在CESM中包括与瞬态气候共同发展的动态南极冰盖，以说明与海洋融合通量相关的反馈，冰架下的海洋变暖以及冰沙地形对区域大气循环的影响。该团队还将运行大型仅CISM实验的集合，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。这样，该项目将尽可能充分地评估导致WAIS崩溃的相互作用的气候和冰盖条件。这项工作通过（1）相对高分辨率的冰原模型改善了以前的工作，该模型可以更好地解析接地线动态，（2）更现实的冰层冰期 - 大气和冰形 - 欧洲耦合，以及（3）可能的气候边界条件更广泛的范围范围，该条件的范围更广泛，次要融化参数和冰上的奖励均可予以宣布。使用基金会的智力优点和更广泛的影响评估标准进行评估。