DURHAM, N.C. – Global warming is projected to spawn more extreme wet and dry weather around the world, according to a recent peer-reviewed study in the Journal of Climate by scientists at Rutgers University, Duke University and the Georgia Institute of Technology.

The projected weather extremes will include more frequent dry spells in the northwestern, central and southern United States and in Mexico, and more frequent heavy rainfall events in south Asia, the Indochinese Peninsula and southern China.

The chief culprit for the extremes, the study finds, is the increasing intensity of subtropical stationary waves that form in northern summers.

As these weather-making waves grow more intense, they spur the formation of more persistent high-pressure systems over the North Pacific and North Atlantic and more persistent low-pressure systems over Eurasia and North America.

The high-pressure systems create conditions that lead to longer periods of dry weather, while the low-pressure systems fuel more extreme wet weather.

“Increasingly strong subtropical stationary waves play an important role in explaining the increase in extremely dry weather in North America and extremely wet weather in south and Southeast Asia,” says Jiacan Yuan, a postdoctoral associate in earth and planetary sciences at Rutgers University-New Brunswick and the Rutgers Institute of Earth, Ocean and Atmospheric Sciences, who led the study.

The researchers’ analysis shows that a significant increase occurred in the waves’ strength between 1979 and 2013. Projections suggest this increase will accelerate as Earth’s climate warms in coming decades.

Wenhong Li, associate professor of climate at Duke’s Nicholas School of the Environment, co-authored the study.

Other co-authors were Robert Kopp of the Rutgers Institute of Earth, Ocean, and Atmospheric Sciences and Yi Deng of Georgia Tech.

Support came from the Rhodium Group as part of the Climate Impact Lab Consortium, and from grants from the National Science Foundation.

CITATION: “Response of Subtropical Stationary Waves and Hydrological Extremes to Climate Warming in Boreal Summer,” Jiacan Yuan, Wenhong Li, Robert E. Kopp and Yi Deng; Aug. 21, 2018, Journal of Climate. DOI: 10.1175/JCLI-D-17-0401.1

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