In a surprising twist in the battle against air pollution, a decade-long effort to reduce pollution in China has unintentionally unmasked a new climate challenge.

According to a group of climate experts, the remarkable success in cutting sulfur dioxide (SO2) emissions by nearly 90% in China, primarily from coal plants, has inadvertently caused a 0.7-degree Celsius increase in average temperatures since 2014, leading to more severe heatwaves.

This unexpected consequence, referred to as "pollution unmasking" by scientists, arises from the removal of aerosols and pollutants that previously acted as a shield, scattering and reflecting solar radiation. The impact of unmasking has been so significant that it appears to have a more immediate effect on temperatures than greenhouse gas emissions themselves in certain industrial Chinese cities.

The experts warn that similar effects could be seen in other highly polluted regions, such as India and the Middle East, if they follow China's lead in reducing sulfur dioxide emissions.

While the reduction of air pollution is essential for public health, the unintended consequence of accelerated warming is a significant concern.

The Intergovernmental Panel on Climate Change (IPCC) had previously noted the link between reducing sulfur dioxide emissions and warming in a 2021 report, highlighting that the absence of this pollution would have already raised global temperatures by 1.6 degrees Celsius, exceeding the goal of limiting warming to 1.5 degrees Celsius.

Despite this revelation, the experts emphasize that the world must not ease its efforts to combat air pollution, which causes millions of premature deaths annually. Instead, they underscore the need for more aggressive measures to reduce greenhouse gas emissions, with a particular focus on methane, a potent short-term climate driver.

While some unconventional proposals like "solar radiation management" involving deliberate aerosol injection into the atmosphere are being considered, addressing methane emissions is seen as a more mainstream approach to offset the effects of pollution unmasking.

As this unintended climate consequence becomes more apparent, experts are searching for strategies to mitigate its impact and prevent catastrophic temperature increases.

Targeting methane emissions is viewed as a key solution that could help maintain the goal of limiting global warming to 1.5 degrees Celsius, despite the challenges posed by pollution unmasking.