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

世界北部地区的永久冻土(永冻层)含有的碳大约是目前地球大气中碳含量的两倍。随着气候变暖，这种碳可能会以温室气体的形式释放。发生在上一个冰河时代末期的快速变暖事件，为了解多少永久冻土衍生的温室气体将加剧正在进行的变暖提供了有用的“自然实验”。古气候指标记录提供了有关多年冻土地区过去变暖事件的时间、强度和位置的洞察，并为过去的多年冻土融化事件提供了有价值的背景。过去多年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，在融化永久冻土形成的湖泊中，以及在侵蚀模式中。这种气候和景观历史可以与来自冰芯的数据进行比较，这些数据详细说明了大气温室气体的来源和浓度。该项目结合了来自多年冻土融化记录、古气候证据和以冰芯为基础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去冰川碳循环的影响。该项目综合了现有的多年冻土融化记录，并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一起进行评估，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在一起，并与退冰期变暖和温室气体增加的气候背景一起进行评估。北极快速变暖数据库的记录提供了气候条件的定量限制，PI将在永久冻土模拟实验中使用这些限制条件。这项工作促进了对永久冻土稳定性的威胁以及由此对大气温室气体的影响的理解。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。

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.