Delaying methane mitigation increases the risk of breaching the 2 °C warming limit

Atmospheric methane levels are growing rapidly, raising concerns that sustained methane growth could constitute a challenge for limiting global warming to 2°C above pre-industrial levels, even under stringent CO₂ mitigation. Here we use an Earth system model to investigate the importance of immediate versus delayed methane mitigation to comply with the 2 °C limit under a future scenario of low CO2 emissions. Our results suggest that methane mitigation initiated before 2030, alongside stringent CO2 mitigation, could enable to limit global warming to well below 2°C over the next three centuries. However, delaying methane mitigation to 2040 or beyond increases the risk of breaching the 2 °C limit, with every 10-year delay resulting in an additional peak warming of -0.1 °C. The peak warming is amplified by the carbon-climate feedback whose strength increases with delayed methane mitigation. We conclude that urgent methane mitigation is needed to increase the likelihood of achieving the 2 °C goal.