Inland waters (rivers, reservoirs, lakes, ponds, streams) and estuaries are globally significant emitters of methane (CH₄) and nitrous oxide (N₂O) to the atmosphere, while global estimates of these emissions have been hampered due to the lack of a worldwide comprehensive dataset with the collection of complete CH₄and N₂O flux components. Here, we synthesize 2,997 in-situ flux or concentration measurements of CH₄ and N₂O from 277 peer-reviewed publications to explore the role of inland waters and estuaries in shaping climate change. We estimate that inland waters including rivers, reservoirs, lakes, and streams together release 95.18 Tg CH₄ yr^-1 (ebullition plus diffusion) and 1.48 Tg N₂O yr^-1 (diffusion) to the atmosphere, yielding an overall CO₂-equivalent emission total of 3.06 Pg CO₂ yr^-1, representing roughly 60% of CO₂ emissions (5.13 Pg CO₂ yr^-1) from these four inland aquatic systems, among which lakes act as the largest emitter for both CH₄and N₂O. Ebullition is noticed as a dominant flux component of CH₄, contributing up to 62–84% of total CH₄fluxes across all inland waters. Chamber-derived CH₄ emission rates are significantly greater than those determined by diffusion model-based methods for commonly capturing both diffusive and ebullitive fluxes. Water dissolved oxygen (DO) showed as a dominant factor among all variables to influence both CH₄(diffusive and ebullitive) and N₂O fluxes from inland waters. Our study reveals a major oversight in regional and global CH₄budgets from inland waters, caused by neglect of the dominant role of ebullition pathways in those emissions. The indirect N₂O EF₅ values established in this study generally suggest a downward revision is required in current IPCC default EF₅ values for inland waters and estuaries. Our findings further indicate that a comprehensive understanding of the magnitude and patterns of CH₄ and N₂O emissions from inland waters and estuaries is essential in defining how these aquatic systems will shape our climate.

The dataset established through worldwide literature review.

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