Investigating Antarctic Ice Sheet-Ocean-Carbon Cycle Interactions During the Last Deglaciation

这个项目调查了过去20,000年来南极冰与海洋的相互作用。南极冰盖是地球气候系统的重要组成部分，因为它与大气、周围的南大洋和下伏的固体地球相互作用。冰盖也是未来海平面上升的最大潜在贡献者，也是气候预测的一个主要不确定性。气候变化可能会引发不稳定，这可能会导致部分冰盖迅速和不可逆转地崩溃。然而，关于南极冰盖和气候系统的其他部分之间的相互作用如何影响其行为、气候和海平面，人们知之甚少，部分原因是大多数气候模型目前没有完全相互作用的冰盖组件。该项目团队将构建一个数值气候模型，其中包括一个互动的南极冰盖，改善研究的计算基础设施。范本代码将在代码共享网站上向公众免费提供。此外，该团队将合成古气候数据，并将其与模型模拟进行比较。这一模型与数据的比较将检验关于深海环流、冰盖、碳和海平面过去变化的三个科学假设。该项目将有助于更好地了解冰海相互作用和过去的气候变化。该项目将检验冰海相互作用对于设定末次冰盛期和随后的冰川消融期间深海环流和碳储存的重要性的想法。新模型将由三个现有的和经过充分测试的部分组成：(1)中等复杂性的同位素启动的气候-碳循环模型；(2)南极冰盖、固体地球和海平面的组合模型；(3)冰山模型。这种耦合将包括海洋温度对冰架基础融化的影响；从冰盖到海洋的淡水通量；以及冰山的崩解、运输和融化。一旦构建和优化，该模型将被应用于模拟最后一次冰盛期和随后的冰川消融。完全耦合、部分耦合或无耦合模式之间的差异将被用来研究冰-海洋相互作用对子午线翻转环流、深海碳储存和冰盖波动的影响。古气候数据综合将把温度、碳和氮同位素、放射性碳年龄、钚-钍比、钕同位素、碳酸盐离子、溶解氧、相对海平面和陆地宇宙成因年龄纳入一个具有一致最新年表的多代理数据库。该项目将支持一名职业生涯早期的科学家、一名研究生、本科生，以及新的和正在进行的国内和国际合作。与当地一家科学博物馆合作的推广活动将通过改善俄勒冈州农村社区的气候知识使其受益。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

This project investigates Antarctic ice-ocean interactions of the last 20,000 years. The Antarctic ice sheet is an important component of Earth’s climate system, as it interacts with the atmosphere, the surrounding Southern Ocean, and the underlaying solid Earth. The ice sheet is also the largest potential contributor to future sea-level rise and a major uncertainty in climate projections. Climate change may trigger instabilities that may lead to fast and irreversible collapse of parts of the ice sheet. However, little is known about how interactions between the Antarctic ice sheet and the rest of the climate system affect its behavior, climate, and sea level, partly because most climate models currently do not have fully-interactive ice-sheet components. The project team will construct a numerical climate model that includes an interactive Antarctic ice sheet, improving computational infrastructure for research. The model code will be made freely available to the public on a code-sharing site. In addition, the team will synthesize paleoclimate data and compare these with model simulations. This model-data comparison will test three scientific hypotheses regarding past changes in deep-ocean circulation, ice sheet, carbon, and sea level. The project will contribute to a better understanding of ice-ocean interactions and past climate variability.The project will test ideas that ice-ocean interactions have been important for setting deep ocean circulation and carbon storage during the Last Glacial Maximum and subsequent deglaciation. The new model will consist of three existing and well-tested components: (1) an isotope-enabled climate-carbon cycle model of intermediate complexity; (2) a model of the combined Antarctic ice sheet, solid Earth, and sea level; and (3) an iceberg model. The coupling will include ocean-temperature effects on basal melting of ice shelves; freshwater fluxes from the ice sheet to the ocean; and calving, transport and melting of icebergs. Once constructed and optimized, the model will be applied to simulate the Last Glacial Maximum and subsequent deglaciation. Differences between model versions with full, partial, or no coupling will be used to investigate the effects of ice-ocean interactions on the Meridional Overturning Circulation, deep ocean carbon storage, and ice-sheet fluctuations. Paleoclimate data synthesis will include temperature, carbon and nitrogen isotopes, radiocarbon ages, protactinium-thorium ratios, neodymium isotopes, carbonate ion, dissolved oxygen, relative sea level, and terrestrial cosmogenic ages into one multi-proxy database with a consistent updated chronology. The project will support an early-career scientist, one graduate student, undergraduate students, and new and ongoing national and international collaborations. Outreach activities in collaboration with a local science museum will benefit rural communities in Oregon by improving their climate literacy.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.