Europe’s increasingly intense summer heatwaves may be partly linked to one of the great successes of modern environmental policy: The removal of air pollution.
New research by scientists at the Barcelona Supercomputing Centre and the UK Met Office, reported by The Telegraph, suggests that the sharp reduction in sulphate aerosol emissions since the 1980s has not only allowed more sunlight to reach the Earth’s surface, but has also altered atmospheric circulation in ways that can intensify and prolong heatwaves over Europe.
The study, published in Geophysical Research Letters, examined why European summer temperatures have risen significantly faster than climate models had previously predicted. It found that the decline in sulphate aerosols was a major contributor to the additional warming observed since around 1980.
Aerosols are tiny particles suspended in the atmosphere. Sulphates, produced largely by burning fossil fuels, can reflect sunlight back into space and have a cooling effect.
Reducing them has therefore improved air quality and delivered major health benefits, but it has also removed part of the atmospheric “sunshade” that had been offsetting some warming.
“On the one hand, the cleaner air lets more sunlight reach the surface,” Markus Donat of the Barcelona Supercomputing Centre said in The Telegraph. “On the other hand, we think that this additional energy causes atmospheric circulation changes that bring even more heat to Western Europe.”
The researchers found that the reduction in European sulphate emissions altered temperature patterns between different parts of the Northern Hemisphere.
Those changes affected quasi-stationary Rossby waves, large-scale atmospheric patterns that can become unusually persistent and help create the high-pressure systems associated with prolonged heatwaves.
The result can be a kind of meteorological “traffic jam”, in which weather systems move more slowly and hot air remains trapped over Europe for longer.
The study found that current climate models have underestimated the role of these circulation changes. According to the researchers, models had suggested that the relevant changes in atmospheric circulation would slightly reduce European summer warming. The observed effect, however, was the opposite, with circulation changes amplifying the additional warming linked to aerosol reductions.
Pedro Roldán-Gómez, one of the study’s authors, said that Europe had warmed around 1°C more than the average of extratropical areas of the Northern Hemisphere since 1980, and around 1.5°C more than the global average.
“Most of this excess warming over Europe can be linked to the reduction of particle emissions,” he said.
The findings are consistent with a second recent study examining European heatwaves, which concluded that greenhouse gases were the dominant driver of the long-term increase in heatwaves between 1940 and 2020, while aerosols had previously masked part of that warming. As aerosol pollution declined, that cooling effect weakened.
The researchers stressed that the findings do not mean that reducing air pollution was a mistake. Sulphate pollution causes serious damage to human health and the environment, and the decline in emissions has brought substantial benefits.
Nor does the research suggest that greenhouse gases are irrelevant to Europe’s warming. The authors found that the reduction in aerosols acted as an additional factor that amplified warming primarily driven by greenhouse gas emissions.
Europe’s temperatures rose more slowly than those of many other regions for much of the 20th century, while high levels of aerosol pollution provided a cooling effect. Since the 1980s, as Europe cleaned up its air, the continent began warming faster.
The study may help explain why climate models have struggled to reproduce the full scale of recent European summer warming and why heatwaves have become particularly persistent.
There is also a possible complication for the future. As other regions, particularly parts of Asia, continue to reduce sulphate emissions, the same “unmasking” effect could contribute to additional warming in those regions.
At the same time, the researchers suggest that the extra warming effect from Europe’s own aerosol reductions may now begin to level off as sulphate emissions have already fallen substantially.
COMMENT: Heat alone does not devour entire provinces. Fire is natural, but catastrophe is political. Iberia in 2025 burns not because the sun is cruel but because its leaders are weak, writes @rpintoborges. https://t.co/6D2TDRS0gG
— Brussels Signal (@brusselssignal) August 27, 2025
