Study: Heat waves expected to be bigger, affect more people

Oct. 11 -- Climate change could trigger much bigger heat waves by mid-century, U.S. researchers report.

Previous research has predicted that the number and intensity of heat waves will increase, but this study is the first to examine changes in their potential physical size.

"As the physical size of these affected regions increases, more people will be exposed to heat stress," said lead author Brad Lyon, an associate research professor at the University of Maine in Orono.

"Larger heat waves would also increase electrical loads and peak energy demand on the grid as more people and businesses turn on air conditioning in response," he added.

The statistics are alarming.

With medium greenhouse gas emission levels, the average size of heat waves could grow 50 percent by mid-century, according to the study. With high emission levels, their average size could increase 80 percent, and more extreme heat waves could more than double in size, it predicted.

The study, published Oct. 7 in the journal Environmental Research Letters, was partly funded by the Climate Observations and Monitoring Program of the U.S. National Oceanic and Atmospheric Administration's Climate Program Office.

Predictions about the growing size of heat waves could help utilities plan for the future, according to the researchers.

"Heat wave size is another dimension of extreme heat that people don't necessarily think of," Lyon said in a NOAA news release. "It's a different vantage point from which to view them and assess their impacts."

The study also found that the length and severity of heat waves could increase substantially, which came as no surprise to the researchers.

"An increase in attributes like magnitude and duration is consistent with expectations of a warming climate," Lyon said. "What is new in our study is the way we calculated them, which allowed us to consider size as a new heat wave dimension."

More information

The World Health Organization has more on climate change and health.

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