Hotspots of irrigation-related US greenhouse gas emissions from multiple sources

Irrigation effectively increases yields and buffers against intensifying climatic stressors to crop productivity but also produces greenhouse gas (GHG) emissions through several pathways including energy use for pumping (on farm and for interbasin water transfers), N₂O emissions from increased denitrification under elevated soil moisture, and degassing of groundwater supersaturated in CO₂. Despite irrigation’s climate adaptation potential, associated GHG emissions remain unquantified. Here we conduct a comprehensive, county-level assessment of US GHG emissions from these irrigation-related pathways, estimating that irrigation produces 18.9 MtCO₂e annually (95% confidence interval 15.2–23.5 Mt), with 12.6 Mt from on-farm pumping, 1.1 Mt from pumping for interbasin transfers, 2.9 Mt from elevated N₂O and 2.4 Mt from groundwater degassing. These emissions are highly spatially concentrated, revealing opportunities for geographically targeted and source-specific GHG mitigation actions. These findings enable strategic consideration of GHG emissions in decision-making associated with irrigation expansion for climate adaptation.