Linking ozone pollution and climate change: The case for controlling methane

Methane (CH 4 ) emission controls are found to be a powerful lever for reducing both global warming and air pollution via decreases in background tropospheric ozone (O 3 ). Reducing anthropogenic CH 4 emissions by 50% nearly halves the incidence of U.S. high‐O 3 events and lowers global radiative forcing by 0.37 W m −2 (0.30 W m −2 from CH 4 , 0.07 W m −2 from O 3 ) in a 3‐D model of tropospheric chemistry. A 2030 simulation based upon IPCC A1 emissions projections shows a longer and more intense U.S. O 3 pollution season despite domestic emission reductions, indicating that intercontinental transport and a rising O 3 background should be considered when setting air quality goals.