The Last deglaciation in Greenland: demystifying the mystery interval

“最后一次冰川消融”指的是从上一个冰河时代到我们现在的气候状态的转变；这一转变发生在大约18,000年前到11,000年前。最后一次冰川消融是全球大规模变暖的最新自然例证，可以帮助科学家更好地理解气候对大气二氧化碳的敏感性、格陵兰冰盖对气候变化的敏感性等具有科学和社会意义的重要问题。该奖项支持对过去23,000年来格陵兰温度和降雪率的新的和改进的重建。这项工作将提高对格陵兰气候历史的科学理解，可以改进格陵兰冰盖模型对过去和未来冰川融化的模拟，并为气候模型模拟提供基准。该奖项支持俄勒冈州立大学的一名研究生和华盛顿大学的暑期本科生实习，为STEM(科学、技术、工程和数学)劳动力做出贡献。研究人员将每年访问该地区的初中和高中进行为期一天的极地研究。该奖项支持气候反馈棋盘游戏的进一步开发和专业设计--这是一项主动学习的课堂活动，旨在教授气候反馈及其在全球气候变化中的作用。研究人员将使用一种新的气候重建策略，该策略结合了来自冰芯的格陵兰气候信息的四个独立来源：钻孔温度、冰的水稳定同位素比率、大气氮中的同位素分馏，以及基于甲烷的冰芯气体年龄-冰龄差异的经验约束；以前的重建只考虑了两个或更少的此类约束。将在格陵兰近东、北大洋和北冰洋2号冰芯上进行甲烷和氮同位素分馏(∂15N-N2)的定向高精度测量，以帮助这些重建，并在北冰洋2号冰芯中复制最近发现的冰川∂15N-N2信号。该奖项支持开发新的模型，将这些新的气候信息来源纳入一个单一的重建。这项工作还包括一系列假设驱动的模拟实验，使用最先进的同位素启用的气候模型，试图回答格陵兰极弱的近场海因里希事件响应和全球季风和热带水文中的强远场响应的矛盾观测。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。

The ‘last deglaciation’ is the transition from the last Ice Age to our current climate state; a transition that took from approximately 18,000 to 11,000 years ago. The last deglaciation is the most recent natural example of large-scale global warming, which can help scientists better understand scientifically and societally important problems such as the sensitivity of climate to atmospheric carbon dioxide and the sensitivity of the Greenland ice sheet to climate change. The award supports new and improved reconstructions of Greenland temperature and snowfall rates for the last 23,000 years. The work will enhance scientific understanding of Greenland climate history, can improve Greenland ice sheet model simulations of past and future ice loss, and provides a benchmark for climate model simulations. The award supports a graduate student at Oregon State University and a summer undergraduate internship at University of Washington, contributing to the STEM (Science, Technology, Engineering and Mathematics) workforce. The researchers will visit regional middle and high schools annually for a day of polar research. The award supports the further development and professional design of a Climate Feedback boardgame – an active-learning classroom activity for teaching climate feedbacks and their role in global climate change. The researchers will use a new climate reconstruction strategy that combines four independent sources of Greenland climate information from ice cores: borehole temperatures, water stable isotope ratios of ice, isotopic fractionation in atmospheric nitrogen, and methane-based empirical constraints on the ice core gas age-ice age difference; previous reconstructions have only considered two or fewer of such constraints at a time. Targeted high-precision measurements of methane and nitrogen isotopic fractionation (∂15N-N2) will be performed on the Greenland NEEM, NGRIP and GISP2 ice cores to aid these reconstructions, and to replicate recently discovered glacial ∂15N-N2 signals in the GISP2 core. The award supports new model development to incorporate these new sources of climatic information into a single reconstruction. The work further includes a series of hypothesis-driven modeling experiments using a state-of-the-art isotope-enabled climate model that seek to answer the paradoxical observation of an extremely weak near-field Heinrich Event response in Greenland, and a strong far-field response in the global monsoon and tropical hydrology.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.