Global Greenhouse Gas Emissions on Croplands

Stabilizing greenhouse gas (GHG) emissions from croplands as agricultural demand grows is a critical component of climate change mitigation. Emissions intensity metrics – including carbon dioxide equivalent emissions per kilocalorie produced (“production intensity”) – can highlight regions, management practices, and crops as potential foci for mitigation. Yet their spatial and crop-wise distribution has been uncertain. Here, we develop global crop-specific circa 2000 estimates of GHG emissions and GHG intensity in high spatial detail, reporting the effects of rice paddy management, peatland draining, and nitrogen (N) fertilizer on CH4, CO2, and N2O emissions. Global mean production intensity is 0.15 Mg CO2e M kcal-1, yet certain cropping practices contribute disproportionately to emissions. Peatland drainage (3.7 Mg CO2e M kcal-1) – concentrated in Europe and Indonesia – accounts for 33% of these cropland emissions despite peatlands producing just 1.1% of total crop kilocalories. Methane emissions from rice (0.54 Mg CO2e M kcal-1), a crucial food staple supplying 15% of total crop kilocalories, contribute 46% of cropland emissions, with outsized production intensity in Vietnam. In contrast, N2O emissions from N fertilizer application (0.034 Mg CO2e M kcal-1) account for only 21% of cropland emissions. We find that current total GHG emissions are largely unrelated to production intensity across crops and countries. Climate mitigation policies should therefore be directed to locations where crops have both high emissions and high intensities.