Global soil N2O emissions constrained by land-use and land-cover changes in recent decades

Atmospheric N₂O, the dominant ozone-depleting substance and a potent greenhouse gas, has risen notably over recent decades. Using a process-based model, we simulated natural ecosystem N₂O emissions from 1990 to 2023, factoring the effects of atmospheric nitrogen deposition, biological nitrogen fixation, rock weathering, and soil uptake. Simulations based on the potential vegetation map (PVM) show average emissions of 6.24 ± 0.72 Tg N yr⁻¹ with a significant upward trend (+0.021 Tg N yr⁻¹) from 1990 to 2023, while ESA-CCI land cover estimates were 30% lower, underscoring the sensitivity of N₂O estimates to land-cover representation. Most emissions stem from background processes (69.8 ± 4.5%), followed by nitrogen fixation (16.3 ± 2.6%), atmospheric deposition (9.2 ± 1.3%), and rock weathering (4.7 ± 1.1%). The accelerating trend of N₂O emissions under changing climate conditions and key uncertainties are tied to used land-cover datasets, limited observation data, and unresolved hydrological extremes.