New Research Sheds Light on 2021 Heat Wave That Killed 72 People in the Portland Area

The latest study corroborates what others over the past year have concluded: that human-caused global warming exacerbated the heat dome but was not its main cause.

New research out of the Lawrence Berkeley National Laboratory corroborates other findings over the past year that show human-caused climate change is not solely to blame for the 2021 heat dome in the Northwest that caused the deaths of 72 people in the Portland area, though it likely intensified the record-setting temperatures.

The intensity of that heat wave, according to a paper published by multiple researchers from the Climate and Ecosystem Sciences Division of the Lab, cannot solely be explained by human-caused warming.

The simulations found an increase of 0.8 to 1 degree Celsius (about 33 degrees Fahrenheit) attributable to global warming, with an increase of 5 degrees Celsius (41 degrees Fahrenheit) by the end of the 21st century. This supports a more complicated, multicausal explanation for the heat wave.

“While it is clear that global warming causes heat waves to be warmer, the unique meteorological conditions behind the 2021 Pacific Northwest heat wave tax our ability to make quantitative estimates of the human contribution,” the study asserts.

Other studies of the heat dome over the past year have come to similar conclusions—that this heat dome was the result of a rare confluence of factors.

The upshot of this is that most research seems to agree that this particular heat wave was unique, and that we are statistically unlikely to have a repeat of the same intensity.

While the heat dome last summer directly killed 72 people people across Multnomah County, deaths from all causes nearly doubled during the week of the event, suggesting indirect deaths as well. Most of those who died in the Portland area were seniors, lived alone and did not have air conditioning.

While temperatures in Portland remained over 10 degrees cooler than last summer’s heat dome, this summer brought its own record-breaker: the longest-running stretch of days when the temperature exceed 95 degrees Fahrenheit. Elevated temperatures for prolonged amounts of time, made more intense by nights when the temperature doesn’t drop, are especially deadly.

That’s because our bodies are often offered reprieve at nighttime when temperatures drop, but when they’re unable to do so, people become more susceptible to heat-related illnesses. Multnomah County reported seven suspected heat deaths caused by the hot spell.