A social media row involving Reform UK's Richard Tice over claims that falling air pollution, not carbon dioxide, is driving heatwaves has drawn attention to genuine climate science about the role of aerosols. While Tice was wrong to dismiss carbon dioxide as the main driver of global warming, scientists say the decline in sulphur pollution from clean-air policies has removed a cooling effect that was previously masking some of the warming caused by greenhouse gases, potentially accelerating temperature rises.

Sulphur dioxide from burning fossil fuels forms reflective aerosol particles that bounce sunlight back into space and brighten clouds, acting like "dust on a greenhouse window" that slows warming. Policies such as the US Acid Rain Program have sharply cut these emissions even as carbon dioxide levels remain near record highs, and researchers including Reto Knutti of ETH Zurich say that once natural fluctuations like El Niño are stripped out, the underlying rate of warming has clearly accelerated. The past three years have been the warmest on record, with the Met Office predicting 2027 will likely overtake 2024 as the hottest year yet.