Recent Changes in Global Ocean N ₂ O Fluxes and Their Relationship to Ocean Climate Variability

While the ocean is a critical regulator of atmospheric nitrous oxide (N 2 O) levels, its specific contribution remains poorly constrained. Here, we implemented an N 2 O module into the Estimating Circulation and Climate of the Ocean‐Darwin (ECCO‐Darwin) to investigate global sea‐air N 2 O fluxes, trends and interannual variabilities. From 1992 to 2017, the model yielded a global the oceanic N 2 O efflux of 2.43 ± 0.43 Tg N yr −1 , with a declining trend of −0.021 ± 0.0031 Tg N yr −2 , attributed mainly to a reduction in N 2 O production induced by strengthened upper‐ocean stratification. The Eastern Tropical Pacific (ETP), Indian Ocean (IO) and Southern Ocean (SO) emerge as the primary three hotspots for N 2 O outgassing, where interannual variability is modulated by regional climate modes. In the ETP and IO, N 2 O fluxes strongly correlate with the El Niño Southern Oscillation index, with correlation coefficients of r = −0.93 and 0.53, respectively. During El Niño, reduced wind speeds and the deepening of the thermocline lead to decreased N 2 O outgassing in the ETP. El Niño events also tend to result in a positive Indian Ocean Dipole, which causes the thermocline in the Eastern Tropical IO to shoal, resulting in increased N 2 O outgassing. In the SO, the interannual variability of N 2 O fluxes is positively correlates with the Southern Annular Mode (SAM) index ( r = 0.76). When the SAM is positive, westerly winds shift poleward, strengthening Ekman pumping and resulting in more subsurface N 2 O‐laden water being upwelled and outgassed. Our study provides a mechanistic understanding of the critical role of ocean‐atmosphere dynamics and climate variability in modulating oceanic N 2 O emissions.