Cleaner Air May Be Unmasking Faster Global Warming Than Expected

During a hot summer in Britain, a deputy party leader shared a claim that cleaner air, not carbon dioxide, was driving heatwaves, prompting scientists to clarify the role of sulphur pollution. Sulphate aerosols from fossil-fuel combustion reflect sunlight and have historically offset some greenhouse-gas warming; recent clean-air policies have sharply cut these emissions. Studies by Reto Knutti’s team at ETH Zurich and others show that the disappearance of this aerosol cooling has contributed to the recent acceleration of global warming, alongside reduced low-cloud cover and faster ocean heating.

Analyses suggest that climate models which accurately reproduce the observed warming also predict a higher climate sensitivity, meaning the same emissions could produce about 25% more warming than earlier estimates. While the aerosol effect adds only a fraction of the total warming, the combined evidence raises concerns that the climate may respond more strongly to greenhouse gases, making rapid emission cuts even more critical.