Cryo-methane emissions - global consequences of permafrost and hydrate destabilization

地球上最大的甲烷储存库在海洋和陆地天然气水合物中，以及永久冻土层内/之下。海相天然气水合物储量约为1.5×10~(-15)m^3，陆源水合物储量约为0.06~0.7×10~(-15)m~(-3)，两者合计约为常规天然气资源量的两倍，约为0.4×10~(-15)m~(-3)。利润率和陆上北极Mallik 2L-38水合物完好地记录了水合物的特征、环境和经济方面。我们利用格陵兰冰中甲烷稳定的碳、氢同位素比值，研究了北冰洋前/年轻仙女木/北冰洋前(YD/PB)过渡期和晚期冰盛期甲烷的快速变化。我们的冰川研究表明，海洋天然气水合物和热带湿地不是晚更新世甲烷变化的原因。我对YD/PB上升的假设是储存在近地表永久冻土中的甲烷的释放。气候变暖导致冰盖前面的永久冻土层融化并释放出被困住的甲烷。今天，我们正在经历一场类似的永冻土退缩。如果我的YD/PB假设是正确的，那么在接下来的几十年里，我们将经历与亚北极变暖类似的大气甲烷快速上升。这可能与陆架气体水合物释放甲烷有关。其影响包括当今全球温室气体预算的戏剧性变化，对当前辐射预算的影响，以及对气候变化的影响。在我即将到来的探索资助期，我希望深入研究加拿大北极不连续永久冻土区和陆架水合物变化对土壤气体通量的控制和速率，特别是甲烷。使用生物地球化学场测量(包括涡流相关、气体成分、同位素、生物标志化合物和微生物分析)并结合建模，我试图确定永久冻土和水合物来源的甲烷是否正在受到亚北极条件变化的影响，2)是否或能够释放出足够的数量和同位素组成，以与我们的YD/PB加拿大和格陵兰岛冰信号相一致，3)将具有显著影响我们未来气候的规模。

Earth's largest repositories of methane are in marine and terrestrial gas hydrates and within/beneath permafrost layers. Although estimates are uncertain, marine gas hydrates store ca. 1.5 x10^15 m^3 and terrestrial hydrates up to 0.06-0.7 x10^15 m^3. Combined they double conventional gas resources of ca. 0.4 x10^15 m^3. Our biogeochemical research of marine hydrates offshore Oregon and Vancouver Is. Margins, and onshore Arctic Mallik 2L-38 hydrate well, documented the character, environmental and economic aspects of hydrates. In concert, we investigated the rapid methane changes at Preboreal /Younger Dryas/Preboreal (YD/PB) transition and Late Glacial Maximum using methane stable C- and H-isotope ratios in Greenland ice. Our ice research indicates that marine gas hydrates and tropical wetlands are not responsible for the Late Pleistocene methane changes. My hypothesis for the YD/PB rise is the release of methane stored in near-surface permafrost soils. Warming causes permafrost layers in front of ice sheets to thaw and release trapped methane. Today, we are experiencing a similar retreat in permafrost. If my YD/PB hypothesis is correct, then in the coming decades we shall experience a similar rapid rise in atmospheric methane as the subArctic warms. This may be combined with the release of methane from shelf gas hydrates. The implications are dramatic shifts in present day global greenhouse gas budgets, impacts on current radiative budgets and influences on climate change. In my coming Discovery Grant period, I wish to intensely investigate the controls and rates of soil gas fluxes, especially methane, from changing discontinuous permafrost regions and shelf hydrates of Canada's Arctic. Using biogeochemical field measurements (including eddy flux correlation, gas composition, isotopes, biomarker compounds, and microbiological assays) coupled with modeling, I seek to determine if permafrost-and hydrate-derived methane: 1) is being influenced by changes in subArctic conditions, 2) is or can be released with sufficient quantity and isotope composition to be consistent with our YD/PB Canadian and Greenland ice signals, 3) will be of a magnitude that can significantly affect our future climate.