Postdoctoral Fellowship: OPP-PRF: Assessing the Contribution of Permafrost-derived Trace Gases in Greenhouse Warming since the Last Glacial Maximum

世界北部地区永久冻土的碳含量大约是目前地球大气中碳含量的两倍。随着气候变暖，这些碳可能会以温室气体的形式释放出来。在最后一个冰期末期发生的快速变暖事件提供了有用的“自然实验”，以了解永久冻土产生的温室气体将加剧持续变暖的程度。古气候代理记录提供了对多年冻土地区过去变暖事件的时间、强度和地点的洞察，以及对过去多年冻土融化事件的宝贵背景。过去的永久冻土融化的证据以几种不同的形式保存下来，即在洞穴沉积物中，在永久冻土融化形成的湖泊中，以及在侵蚀模式中。这种气候和景观历史可以与从冰芯中获得的数据进行比较，后者详细说明了大气温室气体的来源和浓度。该项目结合了来自永久冻土融化记录、古气候证据和基于冰芯的温室气体浓度的数据，以更好地了解变暖和永久冻土融化对冰川消融碳循环的影响。该项目综合了现有的永久冻土融化记录，并将它们与美国国家科学基金会资助的北极快速变暖（OPP-1947981, OPP-1948005）数据库中的古气候记录进行了评估，以更好地了解变暖和永久冻土不稳定如何影响全球碳循环。以前的研究主要集中在“自下而上”的永久冻土融化记录或“自上而下”的基于冰芯的温室气体重建。在这里，这些不同的方法被整合起来，并与冰川消融变暖和温室气体增加的气候背景一起进行评估。来自北极快速变暖数据库的记录提供了气候条件的定量约束，PI将在永久冻土模拟实验中使用这些条件。这项工作促进了对永久冻土稳定性的威胁及其对大气温室气体的影响的理解。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。

Permanently frozen ground (permafrost) in the northern regions of the world holds about twice as much carbon as what currently exists in Earth’s atmosphere. As climate warms, this carbon may be released as greenhouse gases. Rapid warming events, which occurred during the end of the last Ice Age, provide useful “natural experiments” for understanding how much permafrost-derived greenhouse gases will exacerbate ongoing warming. Paleoclimate proxy records provide insight on the timing, intensity, and location of past warming events in permafrost-laden regions and valuable context for past episodes of permafrost thaw. Evidence of past permafrost thaw is preserved in several different forms, i.e., in cave deposits, lakes that formed from thawing permafrost, and in erosional patterns. This climate and landscape history can be compared to data derived from ice cores, which detail the sources and concentrations of atmospheric greenhouse gases. This project combines data from permafrost thaw records, paleoclimate evidence, and ice core-based greenhouse gas concentrations to better understand the effects of warming and permafrost thaw on the deglacial carbon cycle. This project synthesizes existing records of permafrost thaw and evaluates them alongside paleoclimate records in the NSF-funded Rapid Arctic Warming (OPP-1947981, OPP-1948005) database to better understand how warming and permafrost instability influence the global carbon cycle. Previous research has largely focused on “bottom-up” records of permafrost thaw or on “top-down” ice core-based greenhouse gas reconstructions. Here, these disparate approaches are integrated and evaluated alongside the climatic context of deglacial warming and greenhouse gas increases. Records from the Rapid Arctic Warming database provide quantitative constraints on climatic conditions which the PI will use in permafrost modelling experiments. This work advances understanding of threats to permafrost stability and resulting impacts on atmospheric greenhouse gases.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.