UA Research Examining How Heat Waves Are Getting Bigger

TUSCALOOSA, Ala. — Excessive heat is the deadliest weather hazard in the United States, yet there is still a lot to learn about heat waves.

Research by Dr. David Keellings, assistant professor of geography at The University of Alabama, has shown heat waves are becoming larger while also becoming more severe over the last 60 years.

The reason is likely climate change, but how heat waves are getting bigger is not fully understood. Keellings was recently awarded a three-year, $340,000 grant from the National Science Foundation to study the relationship between the size of heat waves and causes across the U.S. with the goal of developing predictive models.

“The grant will support further research into heat waves that have a big impact on human health across the U.S., and it will directly involve stakeholders in emergency response and public health to develop improved planning and response to heat waves,” Keellings said.

A heat wave is abnormally hot weather for the time of year for the location. A heat wave brings temperatures hotter than 95 percent of recorded temperatures for the time of year, or, thought of another way, it can be temperatures that only typically occur every 20 years or more.

They generally occur in high-pressure systems in the atmosphere that block winds and clouds, allowing the sun to bake the air. They can be forecast, but it is difficult to predict the size, duration and intensity.

“The bigger the heat wave becomes, the higher its magnitude and the longer it tends to last,” Keellings said.

The land plays a role with factors such as soil moisture, urbanization and vegetation, and research supported by the grant will explore how these physical variables influence whether a heat wave will be a local event or one smothering several states.

“We’re trying to get at the basic understanding,” he said. “We’re trying to think about heat waves as events with spatial dimensions as opposed to simply thinking of its temperature.”

The data produced from the study could inform climate models and provide information on the path to refining forecasts for heat waves.

Climate change has affected heat waves. A pilot study Keellings led last year found heat waves are getting larger. It is a continuation of his research showing heat waves have become more severe over the past 60 years.

“Temperature and extremes, such as heat waves, are the things we’re most certain about with climate change, and they have definitely become more frequent, higher in magnitude and longer in duration across many parts of the globe,” he said.

Researchers at Michigan State University are also supported by the grant and will work with Keellings on the project.