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Global Nitrous Oxide Budget

Nitrous oxide (N2O) is a long lived greenhouse gas and an ozone-depleting substance, with an atmospheric lifetime of 116±9 years. It is the third most important greenhouse gas leading human-driven climate change, after carbon dioxide and methane.

N2O is accumulating in the atmosphere at an increasing rate, with global emissions of 17 Tg N in 2016, 10% greater than in the 1980s.

The dominant cause of the atmospheric N2O increase is the use of N fertilizers in agriculture, including organic fertilizers from manure produced by livestock.

Agricultural production contributed almost 70% to the global anthropogenic N2O emission in the recent decade of 2007-2016.

Emissions from agriculture are dominated by East Asia, Europe, South Asia, and North America, which are associated largely with the use of synthetic nitrogen fertilizer.

Emissions from Africa and South America are dominated by emissions from livestock manure.

The highest growth rates in N2O emissions come from emerging economies, particularly Brazil, China, and India, where there have been large increases in crop production and livestock numbers.

N2O emissions are increasing faster than any emission scenario developed by the IPCC, consistent with GHG scenarios that lead to global mean temperature increases well above 3°C from the pre-industrial levels.

There is no simple alternative to the use of N fertilizers without greenhouse gas emissions, unlike the case for fossil fuels, which can be replaced with renewables. Food production will always leak N, but we can reduce the amount that is leaked.

Europe has shown that it is possible to bend the curve. Emissions from Europe have decreased over the past two decades through industrial and farming policies to limit the excess of fertilizer applications.

Emissions from the US have remained largely unchanged despite a significant increase in agricultural production, suggesting more efficient use of N fertilizers there.