PORTLAND, Ore. (KOIN) – After a deadly, record-breaking heat wave blanketed the Pacific Northwest in 2021, researchers at Portland State University have found anomalies when it comes to the temperatures the region reached, and health concerns related to the extreme heat.

In a study published Thursday, the PSU research team analyzed 70 publications addressing the causes and outcomes from the heat wave and the potential for similar events in the future.

“It’s still the event of interest for anyone who studies heat waves or the atmospheric patterns that cause them,” said Paul Loikith, associate professor of geography in Portland State’s School of Earth, Environment and Society and a co-author of the study.

According to researchers, scientists in the Pacific Northwest and around the world agreed that the heat wave was caused by a rare combination of meteorological factors.

The weather event was mainly caused by a persistent, and “extraordinarily strong” ridge of high pressure, often called a “heat dome,” which trapped hot air in the region, researchers explained.

In addition to the ridge of high pressure, other factors included moisture from the tropical Pacific Ocean, high solar radiation, low pressure offshore and sinking air over land and unusually dry soils.

According to Loikith, there is no consensus that ridges of high pressure, similar to the one seen during the 2021 heat dome, will become significantly more common.

However, as the climate warms, temperatures seen during the 2021 heat wave – 108, 112 and 116 degrees Fahrenheit over the course of three days in Portland – will become more frequent.

“Essentially, you don’t need a high-pressure ridge of that magnitude to create a heat wave of that magnitude,” Loikith explained. “As you get into a warmer climate, you could have a weaker feature in the atmosphere lead to the same temperatures because the overall background climate is getting hotter.”

According to Loikith, while the likelihood of Portland reaching 116 degrees Fahrenheit again is increasing over time, the probability is still “fairly low.”

“By the end of the 21st century, a heat wave of this magnitude potentially could be experienced once a decade or maybe even more frequently under a higher emissions scenario,” Loikith said.

Researchers added that whether the Pacific Northwest sees another heat wave of equal magnitude this summer cannot be predicted more than one or two weeks in advance.

“Portland summers have warmed by a lot over the last 80 years — four, even five degrees Fahrenheit — but the 2021 event was almost 40 degrees Fahrenheit above average,” Loikith said. “Putting that into context, we’re seeing this steady, gradual warming. We will still have some cooler summers and warmer summers. The cooler summers are warmer than cooler summers were in the past, and the warmer summers are warmer than the warm summers in the past.”

Researchers note there is still more to learn about the atmospheric influences and the long-term impacts of extreme weather events.

‘Anomalously high’

The 2021 heat wave had compounding impacts on human and ecosystem health, researchers added.

According to the study, mortality, heat-induced illness and the number of emergency department visits were “anomalously high,” with the greatest impact seen on older adults, people living alone, people with lower incomes and people without working air conditioning.

As far as ecosystem impacts, researchers learned that browning or scorching of tree leaves and needles was extensive after the heat wave; however, the scope of long-term tree mortality is not yet clear.

After the heat wave, Oregon, Washington and British Columbia created new initiatives to reduce the risk of heat-related illness. These included workplace regulations and programs offering cooling devices to populations at greatest risk. Researchers expect it will take several years before it’s known how effective these interventions are.

“This is an example of why we need to study these things so that we can better understand them and better predict what their likelihood is going to be in the future,” Loikith said. “The studies that we reviewed in this paper help us understand things as basic as atmospheric theory, like things that we still don’t fully understand about the atmosphere, all the way to impacts on ecosystems and on people and everything in between. We are still learning, and that’s making us more prepared.”