IIASA researchers contributed to a new study finding that nitrous oxide emissions continued to rise between 1980 and 2020, marking a 40% increase in man-made emissions of this potent greenhouse gas over this period.

According to a new study by the Global Carbon Project titled, Global Nitrous Oxide Budget (1980-2020), published today in the journal Earth System Science Data, emissions of nitrous oxide – a greenhouse gas more potent than carbon dioxide or methane – continued unabated between 1980 and 2020. The authors point out that alarmingly, in an era when greenhouse gas emissions must decline to reduce global warming, nitrous oxide spilled into the atmosphere in 2021 and 2022 at a faster rate than at any other time in history.

“Nitrous oxide emissions from human activities must decline in order to limit global temperature rise to 2°C as established by the Paris Agreement,” explains study lead author, Hanqin Tian, the Schiller Institute Professor of Global Sustainability at Boston College. “Reducing nitrous oxide emissions is the only solution since at this point no technologies exist that can remove nitrous oxide from the atmosphere.”

The study shows that the concentration of atmospheric nitrous oxide reached 336 parts per billion in 2022, a 25% increase over pre-industrial levels that far outpaces projections previously developed by the Intergovernmental Panel on Climate Change (IPCC). This emissions increase is taking place at a time when global greenhouse gases should be rapidly declining towards net-zero if we are to have any chance of avoiding the worst effects of climate change. According to the authors, the unfettered increase in a greenhouse gas with a global warming potential approximately 300 times larger than carbon dioxide, presents dire policy implications.

Infographic showing the sources of Nitrous Oxide © Global Carbon Project


Drawing on millions of nitrous oxide measurements taken over the past four decades on land and in the atmosphere, freshwater systems, and the ocean, the researchers generated the most comprehensive assessment of global nitrous oxide to date. They also examined data collected from around the world for all major economic activities that lead to nitrous oxide emissions and reported on 18 anthropogenic (man-made) and natural sources and three absorbent “sinks” of global nitrous oxide. Agricultural production accounted for 74% of human-driven nitrous oxide emissions in the 2010s – attributed primarily to the use of commercial fertilizers and animal waste on croplands.

“While there have been some successful nitrogen reduction initiatives in different regions, we found an acceleration in the rate of nitrous oxide accumulation in the atmosphere in this decade,” says Global Carbon Project Executive Director Josep Canadell, who is also a research scientist at Australia’s CSIRO Marine and Atmospheric Research.

Successful nitrogen reduction initiatives include a slowing of emissions in China since the mid-2010s, as well as in Europe during the past few decades – there is however still a lot of work to be done to ensure that emissions of this potent greenhouse gas is reduced significantly. More frequent assessments and an improved inventory of sources and sinks will be crucial for targeting mitigation efforts and achieving the objectives of the Paris Agreement.

“The accelerating rates of nitrous oxide emissions underscore the urgency for innovative agricultural practices as well as the need to tackle emissions from other sources such as industry, combustion, or waste treatment," notes study coauthor Wilfried Winiwarter, a senior researcher in the IIASA Pollution Management Research Group. “Implementing measures through effective policies is essential to meet our climate goals and protect our planet.”

The study was produced by a team of 58 researchers from 55 organizations in 15 countries, including from the IIASA Energy, Climate, and Environment Program.

Adapted from a press release prepared by Boston College.

Tian, H., Pan, N., Thompson, R.L., Canadell, J.G., Suntharalingam, P., Regnier, P., Davidson, E.A., Prather, M., Ciais, P., Muntean, M., Pan, S., Winiwarter, W., et al. (2024). Global Nitrous Oxide Budget (1980–2020). Earth System Science Data. DOI: 10.5194/essd-16-2543-2024


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