Collaborative Research: P2C2: Contributions of northern cold-climate peatlands and lakes to abrupt changes in atmospheric methane during the last deglaciation

这项拟议的研究综合了一系列学科(古生态学、气候学、生物地球化学、地貌学、地质学)的研究，以了解在最后一次冰川消融期间，北方寒冷气候的泥炭地和湖泊对大气甲烷(CH4)浓度(AMC)迅速上升的时间、规模和总体贡献。这项研究将使用北部泥炭地和湖泊发展的全面古生态记录来记录它们过去CH4排放的空间和时间模式。这将使人们能够更好地预测北方生态系统未来的排放量，特别是在气候变暖情景下地表永久冻土融化的情况下。具体地说，PIS建议：(1)综合新的和现有的泥炭地、热岩溶湖、壶湖和其他冰川后湖泊的启动数据，以及汇编不再支持泥炭地或永久冻土的地区的数据，例如以前暴露的大陆架和冰盖南缘，以了解在最后一次冰川消融期间这些AMC来源的时间；(2)分析新的和现有的泥炭宏观化石数据，以估计在全新世期间北部高纬度泥炭地地区从高甲烷排放沼泽演化到低甲烷排放沼泽时的过去CH4通量；(3)使用新的稳定同位素方法和14C测年方法来限制北部泥炭地和湖泊中地面冰融化时形成的甲烷中永久冻土来源的氢和碳的大小和时间；以及(4)根据格陵兰和南极冰芯记录的最近更高分辨率的CH4同位素(13C，D，14C)梯度数据，从自下而上重建过去泥炭地和热喀斯特湖泊的CH4排放及其同位素值，与全球大气CH4源的自上而下建模进行比较。它的全球变暖潜力是二氧化碳的数倍。因此，为了制定未来气候变化的情景，重要的是能够估计由于永久冻土退化将向大气释放多少甲烷。这个项目将限制这一数字。

The proposed research integrates studies in a range of disciplines (paleoecology, climate, biogeochemistry, geomorphology, geology) to understand the timing, magnitude, and overall contribution of northern cold-climate peatlands and lakes to rapid increases in atmospheric methane (CH4) concentrations (AMC) during the last deglaciation. The study will use comprehensive paleoecological records of northern peatland and lake development to document their past spatial and temporal patterns of CH4 emission. This will enable better prediction of future emissions from northern ecosystems, particularly as surface permafrost thaws under scenarios of climate warming. Specifically, the PIs propose to: (1) Synthesize new and existing peatland, thermokarst-lake, kettle-lake and other post-glacial lake initiation data, as well as compiling such data from regions that no longer support peatlands or permafrost, such as on formerly exposed continental shelf and along southern margins of ice sheets, to gain knowledge of timing of these AMC sources during the last deglaciation; (2) analyze new and existing peat macrofossil data to estimate past CH4 flux from northern high latitude peatland regions as they evolved from high- CH4 emitting fens to lower- CH4 emitting bogs during the Holocene; (3) use novel stable isotope approaches and 14C dating to constrain the magnitude and timing of permafrost-derived hydrogen and carbon in CH4 from northern peatlands and lakes that formed when ground ice melted; and (4) compare their bottom-up reconstructions of past CH4 emissions and their isotope values from peatlands and thermokarst lakes with top-down modeling of global atmospheric CH4 sources based on recent, higher resolution data of interhemispheric CH4 isotope (13C, D, 14C) gradients recorded in Greenland and Antarctic ice cores.Methane is a potent greenhouse gas. Its global warming potential is many times that of carbon dioxide. Therefore, in order to develop scenarios of future climate change, it is important to be able to estimate how much methane will be released to the atmosphere due to permafrost degradation. This project will constrain that number.