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

地球冰盖在过去的稳定性告诉我们，它们在面对气候变暖时的韧性。了解全球冰盖变化的规模和时间对于理解过去的冰盖变化与气候变化之间的关系非常重要。然而，我们对2.6万年前冰盖最大的时候冰盖的动态知之甚少。该项目将使用新的地球化学工具来判断白令海峡在上一次冰川周期(过去12万年)发生洪水或裸露的时间。结合计算机模型模拟，这些信息将被用来限定这段时间内以前未知的全球冰量历史。此外，这个项目将支持一名博士生，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。PiPico将开发创新的教学工具，使科学种族主义和帝国主义中的地球科学文化的根源变得清晰可辨。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原住民科学与工程计划的外展活动。全球冰盖增长导致最后一次冰盛期的历史受到的限制很少，因为冰盖的推进和随后的海平面上升在冰川消融期间摧毁了过去冰缘和海岸线的证据。为了解决这种不确定性，该项目将通过限制白令海峡的洪水历史，在上一个冰川周期(12万年)内进行持续的、非传统的海平面重建。测量保护在北极浮游有孔虫壳壁内的有机质的氮同位素比率将阐明北太平洋和北冰洋过去的连通性，从而制约白令海峡当地的海平面历史。将利用全球冰量的不确定性范围进行最先进的冰川均衡调整海平面模拟，以模拟白令海峡的当地海平面。最后，这次持续的白令海峡洪灾重建将被用来测试不同的全球冰量历史的合理性，从而在最后一次冰川峰值之前确定全球平均海平面的高水位和低水位。这一奖项反映了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。

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.