Minimal impact of methane on satellite-era regional climate change

The attribution of global and regional climate change to anthropogenic greenhouse gases (GHGs) is well appreciated. Existing estimates based on radiative forcing studies suggest carbon dioxide (CO ₂ ) has dominated global warming since 1850 with methane (CH ₄ ) the second largest contribution. However, radiative forcing studies involve several assumptions and the attribution of GHGs contributions for other climate change indicators is unknown. Here we quantify the impact of individual GHGs on climate change indicators, including regional climate change, in the satellite era using an attribution approach of counterfactual single-forcing CO ₂ , CH ₄ , and other GHGs coupled climate model simulations. CO ₂ dominates global warming, Arctic Sea ice loss, extreme temperatures and regional warming over North America in the satellite era with CH ₄ and other GHGs contributing merely around 20% and 30% of the CO ₂ contribution, respectively. The results demonstrate that, on multi-decadal or longer time scales, CO ₂ dominates and the contribution of CH ₄ and other GHGs is small and not distinguishable from noise, especially for regional climate changes. Thus, CH ₄ mitigation may not be as effective as previously thought, particularly for regional scale impacts.