Collaborative Research: Bounding global ice volumes over the last glacial cycle using reconstructions of Bering Strait flooding

过去地球冰盖的稳定性告诉我们它们在气候变暖时的复原力。了解全球冰盖变化的幅度和时间对于理解过去冰盖变化与气候变化的关系非常重要。然而，我们对2.6万年前冰盖处于最大时期之前的动态冰盖知之甚少。这个项目将使用新的地球化学工具来判断白令海峡在上一个冰期（过去12万年）被淹没或暴露的时间。与计算机模型模拟相结合，这些信息将用于确定这段时间内以前未知的全球冰量历史。此外，该项目将资助一名博士生，他将通过加州大学圣克鲁斯分校科学与司法研究中心学习科学如何产生社会不平等。PI Pico将开发创新的教学工具，使地球科学文化在科学种族主义和帝国主义中的根源清晰可辨。这些工具将包括在加州大学圣克鲁斯分校和普林斯顿大学的课程中。最后，所有人员都将参加阿拉斯加本土科学与工程项目的外展活动。在末次盛冰期之前，全球冰盖的生长历史并没有得到很好的约束，因为在冰川消融期间，冰盖的推进和随后的海平面上升破坏了过去冰缘和海岸线的证据。为了解决这一不确定性，该项目将通过限制白令海峡的洪水历史，在最后一个冰期（12万年）进行连续的、非传统的海平面重建。测量北极浮游有孔虫壳壁内保护的有机物的氮同位素比率将阐明北太平洋和北冰洋过去的连通性，从而限制白令海峡当地的海平面历史。最先进的冰川均衡调整海平面模拟将使用全球冰量的不确定性范围来模拟白令海峡的局部海平面。最后，这种连续的白令海峡洪水重建将用于测试不同全球冰量历史的合理性，从而确定末次盛冰期前的全球平均海平面高点和低点。该奖项反映了美国国家科学基金会的法定使命，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 stability of Earth’s ice sheets in the past informs our understanding of their resilience in the face of a warming climate. Knowing the magnitude and timing of global ice sheet changes is important for understanding how past ice sheet change related to climate change. However, we know little about how dynamic ice sheets were prior to 26,000 years ago, when ice sheets were at their largest. This project will use new geochemical tools to tell when the Bering Strait was flooded or exposed during the last glacial cycle (the past 120,000 years). In combination with computer model simulations, this information will be used to bound previously unknown global ice volume histories over this time. Further, this project will support a PhD student, who will learn about how science can produce social inequities through the UC Santa Cruz Science & Justice Research Center. PI Pico will develop innovative teaching tools for making legible the roots of geoscience culture in scientific racism and imperialism. These tools will be included in courses taught at UC Santa Cruz and Princeton. Finally, all personnel will participate in the outreach to the Alaska Native Science & Engineering Program.The history of global ice sheet growth leading into the Last Glacial Maximum is poorly constrained, as advancing ice sheets and subsequent sea-level rise during deglaciation destroyed evidence of past ice margins and coastlines. To address this uncertainty, this project will develop a continuous, non-traditional sea-level reconstruction over the last glacial cycle (120,000 years) by constraining the flooding history of the Bering Strait. Measuring nitrogen isotope ratios of organic matter protected within the shell walls of Arctic planktic foraminifera will elucidate the past connectivity of the North Pacific and Arctic Oceans, thus constraining the local sea-level history at the Bering Strait. State-of-the-art glacial isostatic adjustment sea-level simulations will be performed using the range of uncertainty on global ice volumes to model local sea level at the Bering Strait. Finally, this continuous Bering Strait flooding reconstruction will be used to test the plausibility of different global ice volume histories, and thus bound global mean sea-level highstands and lowstands before the Last Glacial Maximum.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.