Water-table drawdown across peatlands increases carbon dioxide (CO₂) and reduces methane (CH₄) emissions. The net climatic effect remains unclear. Based on global observations from 130 sites, we found a positive (warming) net climate effect of water-table drawdown. Using a machine-learning-based upscaling approach, we predict that peatland water-table drawdown driven by climate drying and human activities will increase CO₂ emissions by 1.13 (95% interval: 0.88–1.50) Gt yr⁻¹ and reduce CH₄ by 0.26 (0.14–0.52) GtCO₂-eq yr⁻¹, resulting in a net increase of greenhouse gas of 0.86 (0.36–1.36) GtCO₂-eq yr⁻¹ by the end of the twenty-first century under the RCP8.5 climate scenario. This drops to 0.73 (0.2–1.2) GtCO₂-eq yr⁻¹ under RCP2.6. Our results point to an urgent need to preserve pristine and rehabilitate drained peatlands to decelerate the positive feedback among water-table drawdown, increased greenhouse gas emissions and climate warming.

泥炭地的地下水位下降会增加二氧化碳 (CO ₂ ) 并减少甲烷 (CH ₄ ) 排放。净气候效应仍不清楚。根据来自 130 个地点的全球观测，我们发现地下水位下降对（变暖）净气候有积极的影响。使用基于机器学习的升级方法，我们预测由气候干燥和人类活动驱动的泥炭地地下水位下降将使 CO ₂排放量增加 1.13（95% 区间：0.88-1.50）Gt yr ^-1并将 CH ₄减少0.26 (0.14–0.52) GtCO ₂ -eq yr ^-1，导致温室气体净增加 0.86 (0.36–1.36) GtCO ₂ -eq yr ^-1在 RCP8.5 气候情景下，到 21 世纪末。这在 RCP2.6 下降至 0.73 (0.2–1.2) GtCO ₂ -eq yr ^-1。我们的研究结果表明，迫切需要保护原始和恢复排水泥炭地，以减缓地下水位下降、温室气体排放增加和气候变暖之间的积极反馈。