Recent acceleration in N2O growth rate (2013-2023) is caused by increases of nitrogen-fertiliser use and emissions in northern tropics and southern land

Nitrous oxide (N₂O) is a strong greenhouse gas that contributes significantly to global warming and causes depletion of ozone in the stratosphere. Recent observational records show an unprecedented acceleration in atmospheric N₂O growth, reaching 1.15 ppb yr-1 in 2019–2023, a significant increase compared to 0.68 ppb yr-1 in 2001–2005. This surge in growth rate is particularly pronounced over tropical regions. In this study, we use N₂O observations from globally distributed multi-institutional networks and the MIROC4-ACTM inversion framework to quantify N₂O emissions and identify key regions that are driving the recent acceleration. Our results suggest that the major Asian countries, Brazil, Central and Northern Africa, and the Coterminous United States have increased emission sources in the recent 2.5 decades (1998-2023). Further, the increase in land N2O emissions, at a rate of 106 GgN yr-2 during 1998-2002 to 2019-2023 (1Gg=109g), has been clearly associated with the use of nitrogen fertilisers to support extensive agriculture, as inferred from a terrestrial ecosystem model, statistics of nitrogen fertiliser use and inversion results. The emissions from oceanic regions did not show significant increases in N2O emissions (rate: 7±2 GgN yr-2). Our results underscore the importance for improved climate mitigation strategies and emissions reduction policies by increasing nitrogen-fertiliser use efficiency (NUE) in agricultural land.