Study: Meeting Climate Targets Requires Steep, Separate Cuts to Methane, Not Just CO2

A new study argues that climate targets focused only on carbon dioxide are not enough on their own, and that reaching internationally agreed warming limits requires separate, stringent cuts to methane emissions. The research, published in the journal Communications Earth & Environment, found that even under the most ambitious existing national net-zero targets, an absence of methane reduction would lead to peak warming exceeding 1.85 degrees Celsius above pre-industrial levels.

Methane is the second-largest contributor to global warming after carbon dioxide. It traps heat in the atmosphere more efficiently than carbon dioxide but has a much shorter lifespan, fading after just a few decades, and is produced mainly by agriculture, fossil fuels and waste management.

Climate strategies and models often combine all greenhouse gases into a single "CO2 equivalent" metric, using conversion methods such as GWP20, which measures warming over 20 years, or GWP100, which is used in the emissions scenarios that feed into United Nations reporting and in companies' greenhouse gas accounting. The researchers say these conversions can make methane mitigation appear either urgent or unnecessary depending on the assumptions used, obscuring the real trade-offs.

Instead of relying on a conversion method, the study proposes setting a limit on peak global warming first, then working out the minimum methane reduction needed alongside a given net-zero carbon dioxide target. Modelling steady, linear emissions reductions starting in 2025, the researchers found that limiting warming to 1.7 degrees Celsius under a 2050 net-zero carbon dioxide scenario would require global methane emissions to fall by at least 69% by 2050, relative to 2020.

Only a few countries, including Japan, Mexico and South Korea, currently specify methane mitigation targets, according to the study.