Recent studies suggest that initiatives aimed at reducing air pollution in China and East Asia might have unintentionally contributed to an increase in global warming.
The reduction of aerosol emissions, substances that can help cool the planet by reflecting sunlight, has led to an approximate rise of 0.05 degrees Celsius in global temperatures, attributed to warming trends that began around 2010.
When China adopted strict air quality measures, it managed to cut sulfur dioxide emissions by 75%, according to the researchers.
Sulfate gas, a harmful byproduct from burning fossil fuels and volcanic activity, is essential for forming sulfate aerosols, which are currently the predominant aerosols providing a cooling effect on the planet.
While these particles pose health risks to plants, animals, and humans, they remain a crucial part of Earth’s cooling mechanism.
As clouds form around these aerosols, they absorb solar energy, effectively reducing the sunlight that reaches the ground. In the absence of clouds, aerosols send sunlight back into space.
Before the air quality policies took hold, pollution was a significant cause of premature deaths in China, as highlighted by the study’s authors.
However, with fewer cooling aerosols in the atmosphere, both East Asia and the entire globe are likely to face increased warmth, heightened extreme heat, shifts in monsoon patterns, and possible disruptions in agriculture.
The presence of sulfate levels “partially masks the warming driven by greenhouse gases and alters surface temperature patterns,” the researchers noted.
“While reducing air pollution has obvious health benefits, it also removes a protective layer against climate change without lowering CO2 levels,” commented Robert Allen, a climatology professor at the University of California, Riverside.
He stressed the importance of simultaneous efforts to enhance air quality and reduce greenhouse gas emissions.
Based on simulations utilizing major climate models from 2015 to 2049, Allen and his team forecasted an average annual warming of approximately 0.07 degrees Celsius due to reduced aerosol emissions. Since 2010, global warming has already registered at about 0.05 degrees Celsius.
The emission reductions reflected in their simulations closely aligned with those seen in East Asia from 2010 to 2023, and the authors noted that emissions in the region are likely to keep decreasing.
While the study focused primarily on sulfate aerosols, the researchers underscored that CO2 and methane emissions are the principal contributors to long-term climate change.
“Our research highlights a significant acceleration in recent global warming, which is alarming, but the extent remains minor compared to the sustained warming caused by CO2 and methane,” explained Bjørn Samset, a senior researcher at the Centre for International Climate and Environmental Studies in Norway.
Additionally, Allen pointed out that the rise in global temperatures might be temporary, as aerosols have short lifespans in the atmosphere.
“Sulfur dioxide and sulfate aerosols linger for about a week,” he noted. “Once they are eliminated, warming rates will likely align more closely with longer-term trends.”
As various regions worldwide, including South Asia, Africa, and North America, begin to phase out aerosol emissions, scientists are planning to study how these changes may influence future climate patterns.
“Improving air quality is straightforward for public health,” Allen stated. “However, to mitigate the severe impacts of climate change, we must also reduce CO2 and methane emissions. These efforts need to go hand in hand.”
