Nitrous Oxide Emissions Increased 40% From 1980 to 2020, Accelerating Climate Change, Study Finds

A new study from a team of international scientists has uncovered that nitrous oxide emissions, one of the most potent greenhouse gases, have risen continuously over a 40-year period.

The report, published in Earth System Science Data, found that nitrous oxide (N2O) emissions increased by 40% from 1980 to 2020, reaching around 3 million metric tons per year. 

According to the report, nitrous oxide emissions had the fastest growth rate in 2020 and 2021 since 1980, when tracking became more reliable. In 2020 alone, nitrous oxide emissions reached around 10 million metric tons, with 8 million metric tons attributed to agriculture, Scripps Institution of Oceanography at the University of California San Diego reported.

The warming effects of one pound of nitrous oxide are about 265 times the warming effects from the same amount of carbon dioxide, the U.S. Environmental Protection Agency reported. While nitrous oxide emissions have been rising, the report noted that the amount of nitrous oxide emissions released from natural sources has been mostly steady, meaning the increase could be heavily attributed to human activities.

Even after 2020, nitrous oxide emissions remain unchecked, with a nearly 25% increase in 2022 compared to pre-industrial levels.

“Nitrous oxide emissions from human activities must decline in order to limit global temperature rise to 2°C as established by the Paris Agreement,” Hanqin Tian, lead author of the report and the Schiller Institute Professor of Global Sustainability at Boston College, said in a press release. “Reducing N2O emissions is the only solution since at this point no technologies exist that can remove N2O from the atmosphere.” 

The report found some progress toward curbing these emissions, although more actions are needed, the authors said. Nitrous oxide emissions in Europe have been declining by 31% since the 1930s. While China has been the No. 1 emitter of nitrous oxides since 2010, according to the report, the country has seen the rate of these emissions slow down since the mid-2010s. Following China and rounding out the top 10 emitters are India, U.S., Brazil, Russia, Pakistan, Australia, Indonesia, Turkey and Canada.

In the U.S., agriculture is a major contributor of nitrous oxides, but emissions from industrial activities have declined. Globally, agriculture contributed to about 74% of all nitrous oxide emissions over the past 10 years, the report found.

“While there have been some successful nitrogen reduction initiatives in different regions, we found an acceleration in the rate of N2O accumulation in the atmosphere in this decade,” said Josep Canadell, executive director at the Global Carbon Project and a research scientist at Australia’s Commonwealth Scientific and Industrial Research Organization. “The growth rates of atmospheric N2O in 2020 and 2021 were higher than any previous observed year and more than 30 percent higher than the average rate of increase in the previous decade.”  

Because nitrous oxide emissions have been reaching record highs in the past few years, the report authors have recommended frequent assessments as well as improvements to agricultural practices, such as limiting the use of nitrogen fertilizers to slow emissions. They also noted that there needs to be better recordings of the sources of these emissions as well as nitrous oxide sinks.