Cleaning up the air we breathe may be a win for public health, but it also speeds up global warming. That’s according to a recent study published in Communications Earth & Environment, which linked the recent clean-up of air pollution in East Asia to the acceleration of the climate crisis.
Over the past 15 years, global warming has sped up – and until now, scientists weren’t sure why.
Co-author Dr Robert Allen, climatology professor at the University of California, Riverside, said: “When something like the anomalous, record-breaking warmth of 2023 and 2024 happens, climate scientists start to wonder if there’s a factor we’re missing. This study was our effort to figure out what that might be.”
So, a large team of international scientists analysed simulations from eight major climate models.
They found that most of the acceleration in warming observed since 2010 was likely due to efforts against air pollution in East Asia.
In the same period, China had implemented drastic air quality policies that slashed sulphur dioxide emissions by approximately 75 per cent.
Dr Bjørn Samset, lead author of the study and senior researcher at the Centre for International Climate and Environmental Research in Norway, told BBC Science Focus why pollution has a cooling effect.
“Think back to a polluted or hazy day,” he said. “The particles in the air stop some of the sunlight from reaching the surface and therefore act as a cooling sunshade.
“With air pollution, we’ve been doing this on a global scale for decades, and it’s been counteracting some of the global warming from greenhouse gases.”
Samset explained that removing air pollution, as China has done, also removed some of this shading, “and the artificial cooling we’ve had for a while has started to diminish.”
However, the solution isn’t to leave the pollution there. Allen said: “Air quality improvements are a no-brainer for public health. But if we want to prevent the worst impacts of climate change, we have to cut CO2 and methane, too. The two must go hand in hand.”
Before China's 2010 air quality policies, pollution was a leading cause of premature death in the country - Credit: Jackyenjoyphotography via GettyAs well as cutting greenhouse gases, some scientists have suggested wackier solutions to slowing the climate crisis – such as putting fake pollution back into the air.
Samset said this would involve “adding particles to the stratosphere, or into clouds, where they can have the same effects as air pollution, but without (most of) the negative health impacts.”
To do this, he explained, a plane could spray gases into the air from 20km above the ground – far higher than a passenger flight – or scientists could inject sea spray or other natural particles into clouds.
But co-author Prof Laura Wilcox, a meteorologist at the University of Reading, told BBC Science Focus that such solutions wouldn’t solve the problem.
“Just like air pollution, they’re just masking the warming, not addressing the cause,” she said, adding that we also lack the technology to make them possible.
“The other approach is to actively remove CO2 from the atmosphere,” said Wilcox. “This is called carbon capture, and we are already doing this, but at a very small scale.”
Solutions include planting trees and seaweed, using mechanical trees, and capturing CO2 directly from the air to be stored in rocks.
But the main solution, said Samset, “is to reduce our greenhouse gas emissions, primarily through a shift away from the use of fossil fuels.”
Read more:
- The hidden climate tipping point scientists worry most about
- Climate change will soon make Earth's days longer. Here’s what that means for the planet
- Why making clouds brighter could fight climate change
About our experts
Dr Bjørn Samset is a senior researcher at the Centre for International Climate Research, Norway. He is a physicist and science disseminator, with broad experience in atmospheric science and global climate modelling. Samset is studying precipitation and the role of air pollution in a changing climate, mainly through climate modelling.
Prof Laura Wilcox is a professor of aerosol-climate interactions at the University of Reading, UK. Her research interests include the impact of air pollution on climate change and the climate impact of aviation.
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