four red-headed kids play in a sprinkler. Two are wearing blue shirts and shorts. Two are wearing white shirts and black shorts. They are running through greenish brownish grass.

Researchers say deadly heat waves to be more frequent, intense

By Courtney Flatt
four red-headed kids play in a sprinkler. Two are wearing blue shirts and shorts. Two are wearing white shirts and black shorts. They are running through greenish brownish grass.
The second day of record-breaking heat in the Seattle area. People of all ages took advantage of the sprinklers during a free concert at the Lake Burien School Park. (Credit: Michael B. / Flicker Creative Commons)

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It’s cold this time of year – but even fans of warm summers don’t want to endure the extreme temperatures of 2021. That’s when a deadly heat dome plagued the Northwest and overstayed its welcome.

New climate research shows stronger heat domes could happen more often as the climate changes.

“What surprised me is that the strongest response is occurring in the Pacific Northwest,” said Ziming Chen, a post-doctoral researcher at Pacific Northwest National Laboratory and the lead author of the research study.

With this research, scientists hope to discover what strengthened the weather patterns that caused the extreme heat. The study was published in the journal “npj Climate and Atmospheric Science.”

It starts with warm ocean surface waters in the Pacific Ocean. Like a convection oven  – warm, moist air above the water rises and forms clouds, which creates an atmospheric effect called Rossby waves. That starts a pattern. These waves – along with high pressure – get stuck over the Northwest and the heat increases.

“If you have a high pressure system sitting there, then it causes downward motion. Clouds usually wouldn’t form, so it would be really clear skies, then the sunshine comes in and builds up the heat,” said Ruby Leung, a climate scientist with PNNL.

That heat build-up also dries out the soil – which can lead to even higher temperatures, Chen said. Moist soil cools the air as the moisture evaporates.

Other patterns, such as changing wind conditions, could push the Rossby waves toward North America more often, the study found.

Leung said climate change’s effect on these atmospheric waves means the Northwest will need to improve infrastructure, such as air conditioning.

For example, many houses and apartments in Seattle don’t have AC, which hasn’t always been a problem. That’s likely to change, Leung said.

“Imagine, in the future, if these kinds of really extreme temperatures could happen much more frequently. Then, I think, one should start adapting to this.”

She said if greenhouse gas emissions, like burning fossil fuels, aren’t reduced, the Northwest will likely see more – and worse – heat domes in the future.

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