Cutting methane could slow the recovery of the ozone layer

Reducing methane emissions will slow climate change but could also slow the recovery of the stratospheric ozone layer, new research from the University of Reading shows.

The study found that cutting methane makes two other groups of gases more effective at destroying ozone. When methane levels fall, gases derived from halocarbons and nitrous oxide become more chemically active and break down the ozone layer more quickly. The more aggressive the methane reduction, the slower the ozone layer’s recovery.

Published today (29th May 2026) in Geophysical Research Letters, the research indicates that the recovery of the ozone layer could be set back if action on methane is not matched by continued action on other damaging gases.

Dr James Weber, lead author from the Department of Meteorology, University of Reading, said: “The findings do not suggest that cutting methane is the wrong thing to do. Methane is the second-most important greenhouse gas resulting from human activity, after carbon dioxide, and reducing it remains one of the fastest ways to slow climate change, with benefits for air quality as well. 

“The research shows that the ongoing action to reduce emissions of halocarbons and nitrous oxide becomes even more important if countries also cut methane. Without those additional reductions, the gains from methane cuts could come with an unintended cost to the ozone layer.”

Concerns for human health

The ozone layer sits high in the atmosphere and has been recovering since countries agreed to phase out the chemicals that damaged it, mainly halocarbons called CFCs, under the United Nations’ Montreal Protocol in 1987. The study suggests that by 2100, the total amount of ozone in the atmosphere could be 2.4% lower in a scenario with large methane cuts compared to one without. 

The area of land exposed to the highest levels of ultraviolet radiation, classed as "extreme" by the World Health Organization, could be 30 to 35% larger by 2070 as a result. High UV exposure is linked to skin cancer and other health problems.

Researchers including Weber and Maisie Wright used the UK Earth System Model (UKESM), a computer model that simulates the atmosphere, ocean and land surface, to test what happens to the ozone layer under different levels of methane emission reduction. The team tested a range of scenarios running over the course of this century, from realistic near-term cuts to more extreme reductions used to probe the robustness of the findings.

Weber, J., Wright, M., Collins, W.J., Shine, K.P., O'Connor, F.M., Folberth, G.A., Griffiths, P., Abernethy, S. Methane emission reductions slow stratospheric ozone recovery by amplifying the potency of ozone depleting substances. [10.1029/2025GL119900]