Year‐2020 Global Distribution and Pathways of Reservoir Methane and Carbon Dioxide Emissions According to the Greenhouse Gas From Reservoirs (G‐res) Model
Year‐2020 Global Distribution and Pathways of Reservoir Methane and Carbon Dioxide Emissions According to the Greenhouse Gas From Reservoirs (G‐res) Model
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DOI：
10.1029/2020gb006888
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发表时间：
2021-06
影响因子：
5.2
通讯作者：
J. Harrison;Y. Prairie;S. Mercier-Blais;C. Soued
中科院分区：
文献类型：
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作者：
J. Harrison;Y. Prairie;S. Mercier-Blais;C. Soued
总的来说，水库构成了碳基温室气体（GHG）的重要全球来源。然而，全球对水库二氧化碳（CO2）和甲烷（CH 4）排放量的估计仍然不确定，在最近的分析中变化超过四倍。在这里，我们提出了来自水库的温室气体（G-res）模型的全球应用结果，其中我们通过特定的通量途径，以空间和时间上明确的方式，作为水库特征的函数，估计每个区域和每个水库的CO2和CH 4通量。我们展示：（a）通过脱气和沸腾作用产生的CH 4通量比先前认识到的要大得多，扩散CH 4通量比先前估计的要低，而CO2排放量与过去工作中报告的排放量相似;（B）每区域水库GHG通量比先前研究所建议的高29%以上，这在很大程度上是由于我们在全球估计中新纳入了脱气通量; CO2通量是北方地区的主要排放途径，CH 4脱气和沸腾在热带和亚热带地区占主导地位，热带和亚热带地区的温室气体总通量最高;以及（d）水库温室气体通量对输入参数非常敏感，这些参数在未来几十年内既没有受到很好的约束，又可能受到气候变化的强烈影响（温度和沿岸的面积等参数，后者可能因预计伴随着表层沃茨变暖的温跃层加深而扩大）。总之，这些结果突出表明，迫切需要更好地了解与气候相关的温室气体排放驱动因素，并通过CH 4沸腾和脱气更好地量化温室气体排放。
Collectively, reservoirs constitute a significant global source of C‐based greenhouse gases (GHGs). Yet, global estimates of reservoir carbon dioxide (CO2) and methane (CH4) emissions remain uncertain, varying more than four‐fold in recent analyses. Here we present results from a global application of the Greenhouse Gas from Reservoirs (G‐res) model wherein we estimate per‐area and per‐reservoir CO2 and CH4 fluxes, by specific flux pathway and in a spatially and temporally explicit manner, as a function of reservoir characteristics. We show: (a) CH4 fluxes via degassing and ebullition are much larger than previously recognized and diffusive CH4 fluxes are lower than previously estimated, while CO2 emissions are similar to those reported in past work; (b) per‐area reservoir GHG fluxes are >29% higher than suggested by previous studies, due in large part to our novel inclusion of the degassing flux in our global estimate; (c) CO2 flux is the dominant emissions pathway in boreal regions and CH4 degassing and ebullition are dominant in tropical and subtropical regions, with the highest overall reservoir GHG fluxes in the tropics and subtropics; and (d) reservoir GHG fluxes are quite sensitive to input parameters that are both poorly constrained and likely to be strongly influenced by climate change in coming decades (parameters such as temperature and littoral area, where the latter may be expanded by deepening thermoclines expected to accompany warming surface waters). Together these results highlight a critical need to both better understand climate‐related drivers of GHG emission and to better quantify GHG emissions via CH4 ebullition and degassing.