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.

中文翻译：

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根据水库温室气体 (G-res) 模型，2020 年全球水库甲烷和二氧化碳排放的分布和途径

总的来说，水库构成了基于碳的温室气体 (GHG) 的重要全球来源。然而，全球对储层二氧化碳 (CO ₂ ) 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，我们展示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路径并以空间和时间明确的方式估计每个区域和每个水库的 CO ₂和 CH ₄通量，作为储层特征的函数。我们表明：（a）通过脱气和沸腾产生的CH ₄通量比以前认识到的扩散 CH ₄通量大得多通量低于之前的估计，而 CO ₂排放量与过去工作中报告的相似；(b) 单位面积的水库温室气体通量比以前的研究建议的高出 29% 以上，这在很大程度上是由于我们在全球估计中新加入了脱气通量；(c) CO ₂通量是北方地区和 CH ₄的主要排放途径脱气和沸腾在热带和亚热带地区占主导地位，热带和亚热带地区总储层 GHG 通量最高；(d) 水库 GHG 通量对输入参数非常敏感，这些参数在未来几十年中既受约束又很可能受到气候变化的强烈影响（温度和沿海地区等参数，后者可能通过加深温跃层而扩大）伴随地表水变暖）。这些结果共同强调了迫切需要更好地了解温室气体排放的气候相关驱动因素，并通过 CH ₄沸腾和脱气更好地量化温室气体排放。