Berkeley Lab researchers find climate change affects East Asian monsoon rains

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Research by Lawrence Berkeley National Laboratory, or Berkeley Lab, suggests that climate change could shift East Asian monsoon rains — which more than a billion people rely on for their water needs — toward the equator, possibly impacting resource management and people’s daily lives.

The East Asian monsoon is closely linked to the Hadley cell, the tropical atmospheric circulation pattern the Berkeley Lab team studied, which it found will likely shift and constrict as the climate continues to warm, according to a Berkeley Lab press release. These changes in the Hadley cell could result in less rainfall in certain regions.

“People need water to live, and plants need water to grow,” said Da Yang, the principal investigator on the project and assistant professor of atmospheric science at UC Davis, in an email. “Understanding how monsoon systems respond to climate change is, therefore, of primary importance.”

The significance of the team’s results does not lie in the possible effects of climate change on the airflow system, but in how the results differ from previous research on these effects. Studies have shown that the Hadley cell will expand toward the Earth’s poles, but by analyzing changes in the airflow system during different seasons, Yang and his team found that the cell could contract toward the equator during the months of June and July, according to the press release. 

This contraction, which the team attributes to warming at the equator, could have “profound” effects on the subtropical regional climate, according to the press release. Because of these changes, monsoon rains will likely shift toward the equator during the current peak rainfall season in East Asia and significantly impact regional rainfall patterns.

“The monsoon is an important water resource to East Asia and large parts of China,” Yang said in the press release. “So how it moves or changes with climate will have a huge impact on water resource management and on the daily lives of people in these areas.”

Yang said his team used computer modeling and fluid dynamics theories to complete their research. They used a U.N. Intergovernmental Panel on Climate Change “worst-case climate change scenario” to model the climate for 2070 to 2100, according to the press release.

Though a contraction of the Hadley cell is evident in the team’s model, the question moving forward, however, is whether this will be observed in the coming years. According to the press release, preliminary results over the past 30 years suggest that the cell’s patterns can be accounted for by natural variability.

“The consequences of climate change, as suggested in this study, are waiting to be seen,” Yang said in the press release.

Contact Emily Hom at [email protected] and follow her on Twitter at @hom_emily.