Carbon and nitrogen losses from degraded wetlands and methane emissions from flooded wetlands are both important sources of greenhouse gas emissions. However, the net-exchange dependence on hydrothermal conditions and wetland integrity remains unclear. Using a global-scale in situ database on net greenhouse gas exchanges, we show diverse hydrology-influenced emission patterns in CO₂, CH₄ and N₂O. We find that total CO₂-equivalent emissions from wetlands are kept to a minimum when the water table is near the surface. By contrast, greenhouse gas exchange rates peak in flooded and drained conditions. By extrapolating the current trajectory of degradation, we estimate that between 2021 and 2100, wetlands could result in greenhouse gas emissions equivalent to around 408 gigatons of CO₂. However, rewetting wetlands could reduce these emissions such that the radiative forcing caused by CH₄ and N₂O is fully compensated by CO₂ uptake. As wetland greenhouse gas budgets are highly sensitive to changes in wetland area, the resulting impact on climate from wetlands will depend on the balance between future degradation and restoration.

退化湿地的碳和氮损失以及淹没湿地的甲烷排放都是温室气体排放的重要来源。然而，净交换对热液条件和湿地完整性的依赖性仍不清楚。使用全球规模的净温室气体交换原位数据库，我们展示了 CO ₂、CH ₄和 N ₂ O 中受水文影响的不同排放模式。我们发现总 CO ₂- 当地下水位接近地表时，湿地的等效排放量保持在最低水平。相比之下，温室气体交换率在洪水和排水条件下达到峰值。通过推断当前的退化轨迹，我们估计在 2021 年至 2100 年间，湿地可能导致相当于约 408 千兆吨 CO ₂的温室气体排放。然而，再润湿湿地可以减少这些排放，从而使 CH ₄和 N ₂ O 引起的辐射强迫完全被 CO ₂吸收所补偿。由于湿地温室气体收支对湿地面积的变化高度敏感，因此湿地对气候的影响将取决于未来退化与恢复之间的平衡。