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

地球上最大的甲烷储存库位于海洋和陆地的天然气水合物以及永久冻土层内/下。虽然估算值不确定，但海洋天然气水合物可储存约1.5 x10^15 m^3，陆地水合物可储存0.06-0.7 x10^15 m^3。它们加起来使常规天然气资源量增加了一倍，约为0.4 x10^15 m^3。我们的生物地球化学研究海洋水合物俄勒冈和温哥华近海。边际区和陆上Arctic Mallik 2L-38水合物井记录了水合物的特征、环境和经济方面。利用格陵兰冰中甲烷稳定的C-和h -同位素比值，研究了前寒武纪/新仙女木纪/前寒武纪（YD/PB）转变和晚冰期的甲烷快速变化。我们的冰研究表明，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释放。变暖导致冰盖前的永久冻土层解冻，释放出被困的甲烷。今天，我们正经历着类似的永久冻土消退。如果我的YD/PB假设是正确的，那么在未来几十年里，随着亚北极变暖，我们将经历类似的大气甲烷快速上升。这可能与大陆架天然气水合物中甲烷的释放相结合。其含义是当前全球温室气体收支的急剧变化，对当前辐射收支的影响以及对气候变化的影响。在我即将到来的发现基金期间，我希望深入研究加拿大北极不断变化的不连续永久冻土区和大陆架水合物对土壤气体通量的控制和速率，特别是甲烷。利用生物地球化学场测量（包括涡流通量相关性、气体成分、同位素、生物标志物化合物和微生物分析）与建模相结合，我试图确定永久冻土和水合物产生的甲烷是否：1)正在受到亚北极条件变化的影响；2)正在或能够以足够的数量和同位素组成释放，与我们的YD/PB加拿大和格陵兰冰信号一致；3)将具有显著影响我们未来气候的量级。

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.