The lifetime of nitrous oxide is decreasing more quickly than expected, which is changing climate projections.
Scientists at the University of California, Irvine report that climate change is accelerating the breakdown of nitrous oxide in the atmosphere. This gas is both a powerful greenhouse contributor and a key ozone-depleting substance, and its faster removal is adding new uncertainty to climate projections for the remainder of the 21st century.
Drawing on two decades of satellite measurements from NASA’s Microwave Limb Sounder , researchers from UC Irvine’s Department of Earth System Science determined that the atmospheric lifetime of N2O is shrinking by about 1.4 percent per decade.
This trend reflects climate-driven changes in stratospheric temperature and circulation patterns, and its magnitude is similar to the spread between the emissions scenarios used by the Intergovernmental Panel on Climate Change.
A major greenhouse gas at stake
Nitrous oxide ranks as the third most important long-lived greenhouse gas after carbon dioxide and methane, and it is now the leading ozone-depleting substance linked to human activity. Concentrations reached roughly 337 parts per billion in 2024 and are rising at close to 3 percent per decade. Prather emphasized that accurately tracking its behavior is essential for both climate mitigation strategies and efforts to protect the ozone layer.
The study shows that estimating future N2O levels requires more than accounting for emissions from agriculture, industry, and natural sources. It also depends on how climate change alters the stratosphere, where this gas is broken down. This atmospheric region extends from about 10 to 50 kilometers above Earth’s surface.
Observations reveal accelerating decay
According to the findings, the average atmospheric lifetime of nitrous oxide is currently about 117 years, but it is shortening by roughly one and a half years each decade.
