According to a new study, air pollution spikes in Southeast Asia, along with pollution reductions in Europe, may have had a significant impact on European and Asian weather patterns over the past few decades.
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According to scientists at the University of Reading’s evaluation of weather records and climate models, variations in pollution levels in the two regions were likely the major driving force behind adjusting atmospheric conditions that favored prolonged summer extremes in Europe and caused dry spells in Central Asia.
According to new research published in Nature Communications, air pollution increases between 1979 and 2019 reduced the temperature differential between the two locations, weakening the jet stream over Asia considerably.
These high-altitude winds have a significant impact on atmospheric circulation in the Northern Hemisphere and help to define weather in Europe and other mid-latitude regions.
Our findings suggest changes to air pollution had a greater influence on Northern Hemisphere summer weather than we thought.
Dr. Buwen Dong, NCAS scientist, University of Reading
“The research counters previous suggestions that the weakening of the summer jet stream was the result of rapid warming in the Arctic due to greenhouse gas emissions. It highlights another significant role human activity plays in driving extreme weather over vast regions,” added Dong.
Since pollution particles hinder heat from the sun from getting to the ground, air pollution is believed to have a direct impact on surface temperatures.
Pollution spikes in China and other parts of South and East Asia over the last 40 years have resulted in reduced surface temperatures, whereas pollution reductions in Europe have resulted in brighter skies and warmer temperatures.
Temperature changes at different latitudes lowered vertical wind shear, weakening the summertime Eurasian subtropical westerly jet — the ribbon of wind that stretches east from the North Atlantic Jet Stream into Central Asia and northern China — by 7% over the period.
The scientists looked at the effects of greenhouse gas emissions and pollution components individually and discovered that the former genuinely caused a strengthening of the jet stream, but was overpowered by air pollution’s effects.
As South East Asian countries fulfill commitments to cut their air pollution levels over the coming decades, we would expect to see the jet stream strengthen over Eurasia once again, potentially reducing the likelihood of prolonged heatwaves but increasing the likelihood of strong cyclones in mid-latitudes.
Dr. Buwen Dong, NCAS scientist, University of Reading
Journal Reference:
Dong, B., et al. (2022) Recent decadal weakening of the summer Eurasian westerly jet attributable to anthropogenic aerosol emissions. Nature Communications. doi.org/10.1038/s41467-022-28816-5.