Northwest "heat dome" signals global warming's march

The dangerous heat wave enveloping the Pacific Northwest is shattering weather records by such large margins that it is making even climate scientists uneasy.

Why it matters: Infrastructure, including heating and cooling, is built according to expectations of a "normal" climate. Human-caused climate change is quickly redefining that normal, while dramatically raising the likelihood of events that simply have no precedent.

• These risks include extreme heat events that can have unusually high impacts.
• That is exactly what is playing out now, with a region of the country largely devoid of air conditioning suffering through unheard-of temperatures over a prolonged stretch of time.
• In the past, such events have proven to be especially deadly, killing more than 70,000 in Europe in 2003, for example.

Driving the news: The heat wave is shattering all-time temperature records in the U.S. and Canada. Portland, Oregon reached 112°F on Sunday, breaking the all-time record of 108°F set just the day before.

• Canada set a national all-time heat record on Monday, smashing the old record by nearly 3°F.
• The buildings in these regions were not built for extreme heat, and the people living there are not accustomed to it. Public officials have been scrambling to get people to use cooling shelters to escape the sweltering temperatures.

Between the lines: "Because of the fact that climate change has made heatwaves like this much more likely and intense, we might very well reach the tipping point of what our infrastructure and other societal systems are able to deal with," Friederike Otto, of the University of Oxford, told Axios.

How it works: The heat dome over the Northwest, which is a sprawling, intense area of high pressure aloft, causes air to sink, or compress. As it does so, the air temperatures increase. Winds blowing from land to sea around this high are pushing temperatures higher.

• Studies have shown that severe heat events such as this one are now on average about 3°F to 5°F hotter than they would be without the many decades of greenhouse gas emissions.

The big picture: However, climate scientists tell Axios this actually understates climate change's influence, since warming is also altering weather patterns in ways that makes strong heat domes more common and prolonged.

• Daniel Swain, a climate researcher at UCLA, told Axios that the mean warming in the region is "more likely a floor than a ceiling," given climate change's potential effects on atmospheric circulation, soil moisture, and other conditions that can amplify extreme heat.
• In addition, Swain said a focus on tipping points within the climate system alone may be misguided. He also warned of "systemic failures," citing the operation of the power grid as an example of systems that can fail in extreme weather. (See: Texas, winter 2021.)

Of note: Scientists may also be missing part of the tie between global warming and extreme events, creating an even greater societal vulnerability to these events since we're not properly anticipating them and hardening our infrastructure, according to Michael Mann, a climate researcher at Penn State.

• Mann and his colleagues have zeroed in on persistent, unusual contortions in the jet stream, which is the high altitude river of air that helps steer storms, as being linked with heat extremes such as this one.
• Climate models, he says, don't come close to simulating how such patterns are changing in frequency and magnitude as the world warms.

The bottom line: "If our decision makers do not take this heat wave as a harbinger of things to come and act quickly to adopt the climate change policies we all know are needed, I fear for the future of humanity," Jean Flemma, an oceans policy expert living in Portland, told Axios on Sunday.

• "This is not sustainable in a city like [Portland] that was not built for this scenario."