As heat waves become more frequent around the world, researchers at UT-Austin found that the decline of aerosols in the atmosphere could be increasing the frequency of prolonged temperature extremes, especially in densely populated areas.
Aerosols are liquid or solid particles in the atmosphere that come from anything from agricultural burning to industrial pollutants to construction, according to Geeta Persad, assistant professor in the Jackson School of Geosciences at UT-Austin. Essentially, what one sees on a hazy day in the air is aerosols.
“When they’re in the atmosphere, [aerosols] actually reflect sunlight and they also can make clouds brighter, and both of those things cool the planet,” Persad told the Chronicle. “But these aerosol particles have a lot of differences from greenhouse gases. For one thing, they tend to stay concentrated near the places where they’re being produced, which, if they’re being produced by human activities, are going to tend to be the places where people live.” Greenhouse gases, on the other hand, last in the atmosphere for decades to centuries, meaning they easily distribute around the planet.
Other studies have proven that the decline of aerosols can lead to more heat waves, Persad said. However, her team’s study particularly showed that the pattern of heat waves corresponded to where people live.
“When we look at the impact of things like heat waves and other climate extremes, we start to see more of those being revealed in places where people live, because these aerosols were masking warming effects.” – Geeta Persad, UT-Austin
“When we look at the impact of things like heat waves and other climate extremes, we start to see more of those being revealed in places where people live, because these aerosols were masking warming effects,” Persad said.
Heat waves have already started increasing in North America and Europe, Persad said. But, as places like South Asia and Sub-Saharan Africa continue to industrialize and lower their aerosol emissions, heat waves will most likely hit those areas the hardest.
Persad told the Chronicle that Central Texas could see the same impacts of lowered aerosol emissions, especially as temperatures worldwide have increased over the past 10-20 years.
While aerosols do suppress the amount of heat waves, Persad said it’s worth it to lower the planet’s amount of emissions due to public health concerns. Aerosol pollutants lead to between 3 million and 8 million deaths per year due to lung cancer, respiratory diseases, heart disease, and increased risk of stillbirths.
“One of the issues is that these aerosol particles are smaller than the width of a human hair,” Persad said. “When we inhale them, they can easily get into our bloodstream through our lungs.”
Clearly we have to take the good with the bad when it comes to reducing aerosols in the air. The study states that as aerosol emissions continue to decline, the amount of global average heat waves per year – currently about 40 days – is expected to nearly triple to 110 days by 2080.
This article appears in August 29 • 2025.