Methane and Near-Term Warming

Methane is a powerful greenhouse gas that absorbs outgoing infrared radiation and warms the atmosphere. Because it remains in the atmosphere for only about 12 years, sustained emission cuts can reduce its concentration and warming influence within decades, much faster than comparable carbon dioxide reductions affect accumulated warming.

Atmospheric lifetime and rapid concentration response

Methane is a short-lived climate pollutant. Most atmospheric methane is removed through reaction with hydroxyl radicals in the troposphere, while smaller amounts are removed by soils and other processes.

• When emissions fall, existing methane continues to be destroyed by natural sinks, so its atmospheric burden begins declining relatively quickly.
• Methane concentrations respond to emission changes over years to decades because its atmospheric lifetime is relatively short.

Why the warming response is substantial

Methane has much greater warming strength per unit mass than carbon dioxide, especially over a 20-year time horizon. Lower methane concentrations therefore reduce radiative forcing relatively rapidly.

• Methane reductions also limit the formation of tropospheric ozone, itself a greenhouse gas and air pollutant.
• Reducing emissions from fossil-fuel systems, livestock, rice cultivation and waste can therefore moderate the rate of warming in the near term.

Complement, not substitute, for carbon dioxide reduction

Methane mitigation can lower the near-term warming peak and slow the rate of temperature increase, but it cannot replace net-zero carbon dioxide emissions. Carbon dioxide accumulates and influences climate for centuries or longer, making deep CO2 reductions essential for long-term temperature stabilisation.

• The strongest climate strategy combines rapid, sustained methane cuts with deep reductions in carbon dioxide and other long-lived greenhouse gases.