Since around 2010, the pace of global warming has accelerated, contributing to a succession of record-breaking warm years. The exact cause of this rapid increase remains one of the major unsolved questions in climate science.
East Asia’s Pollution Reductions as a Key Driver
A recent study suggests that significant reductions in air pollution — especially across China and other parts of East Asia — are playing a crucial role in this acceleration.
Earlier research pointed to cuts in sulfur emissions from the shipping industry as a potential factor. However, those reductions only began in 2020 and appear insufficient on their own to account for the observed warming trend.
Some NASA scientists have proposed that changes in cloud formations, particularly in tropical regions or over the North Pacific, might also contribute.
China’s Air Quality Policies Come Into Focus
One important element that hasn’t been fully considered until now is the massive effort by East Asian countries, led by China, to reduce air pollution and improve public health through aggressive clean air policies.
Since roughly 2013, sulfur dioxide emissions in East Asia have declined by about 75%. Notably, this reduction aligns closely with the period when the global temperature rise began to quicken.
This new study investigates how improvements in East Asian air quality might be influencing global temperatures, drawing on simulations by eight international climate modeling teams.
The research suggests that air pollution may have been concealing the full effects of greenhouse gases. As pollution levels drop, more of the warming caused by human emissions becomes apparent.
Air Pollution Previously Helped Cool the Planet
Air pollution, while harmful to human health, has historically reflected sunlight and cooled Earth’s surface. Over the past century, it may have suppressed warming by as much as 0.5°C. Now, with cleaner air and rising greenhouse gas levels, this cooling effect is diminishing — leading to faster warming.
Modeling the Air Pollution Cleanup
The research team ran 160 simulations using eight global climate models to examine how pollution reduction in East Asia affects global temperature and rainfall.
Their simulations modeled a cleanup scenario similar to real-world changes since 2010 and found an added warming of approximately 0.07°C. Though small in absolute terms, this figure helps explain the recent surge in global warming, especially when removing the noise from natural climate variability like El Niño.
Under normal trends, the Earth should have warmed about 0.23°C since 2010. In reality, the observed increase was closer to 0.33°C. While most of the excess 0.1°C can be attributed to reduced pollution in East Asia, additional contributors include declining sulfur from shipping and a spike in atmospheric methane.
Pollution cools the planet by scattering sunlight or altering cloud behavior to enhance reflection. The reduction in East Asian emissions has cut this cooling effect, both locally and across the broader Pacific region.
Cleaner air over East Asia also means fewer particles are transported across the North Pacific, reducing reflective cloud cover over the eastern Pacific. Satellite data confirms this pattern, showing a warming trend in the North Pacific — consistent with the modeling results.
While greenhouse gases remain the primary driver of climate change, the drop in air pollution has lifted an artificial “cooling veil” that had masked part of the warming. This didn’t create new warming, but rather exposed more of the warming already in motion.
Global warming is expected to persist for decades, with long-lasting impacts from past and future emissions. By contrast, air pollutants leave the atmosphere relatively quickly. That means the recent burst in warming due to cleaner air may be temporary — but it’s a striking reminder of how multiple human activities can influence the climate in complex ways.
Read the original article on: Science Alert
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