Another extreme heat wave in the West threatens historic highs

It has become a common concern in recent years – extreme heat waves afflict the western United States. Today, for the third time since early June, a life-threatening heat wave is underway. Although this event should not be as unprecedented as the Pacific Northwest heatwave last week all-time records will be set in big cities like Las Vegas, Fresno and Redding, Calif.

This latest heat wave follows the hottest June on record in the United States. New study released Wednesday shows the Pacific Northwest heat wave from June 27-29 has been made at least 150 times more likely by man-made climate change and, even in today’s hot climate, is a rare event over 1,000 years. The study, carried out by a collaboration of 27 climatologists, warned that if we continue to warm the climate, extreme heat waves like this will occur once every 5 to 10 years by mid-century.

Although the Pacific Northwest will be warm for the next few days, the core of this latest thermal dome is centered further south, over the desert southwest and southern California.

Heating domes are persistent mountains of hot air stacked vertically in the atmosphere, caused by slow or even stuck patterns in the jet stream, called blocks.

This means that the hottest temperatures will be found in areas like Las Vegas and Redding. In these two cities, highs are expected to reach around 117 to 119 degrees Fahrenheit. If the mercury exceeds these readings, all-time highs will drop again.

On Saturday and Sunday, the high temperature is expected to reach 130 degrees in Death Valley. If this threshold is reached, it will bind what is considered to be the hottest temperature ever reliably measured on Earth, which took place last year in Death Valley. (The world record of 134 degrees, set in Death Valley in 1913, is hotly contested by climatologists, but still considered official.)

The heatwave will peak on Sunday and will begin to ease early next week. But signs that this global pattern of global blockage will ease soon are rare. It is therefore likely that such thermal domes will continue to reappear from place to place throughout the summer.

In each case, man-made climate change is making these heat waves more intense. Scientists have determined a rule of thumb: With the long-term average global temperature increasing by 2 degrees Fahrenheit since 1900, the intensity of the heat wave is expected to increase by about double, or 4 degrees Fahrenheit. That’s according to Professor Geert Jan van Oldenborgh, World Meteorological Attribution Scientist, Royal Netherlands Meteorological Institute.

But he says the Pacific Northwest heat wave defied that logic, with temperatures far exceeding expectations. Until recently, he explained, “It seemed that the heatwaves of the regions behaved well, with temperatures gradually increasing with global warming, about twice as fast as the global average temperature. And then we had this.”

Oldenborgh mentions that one possible explanation for these out-of-bounds heat waves is the possibility that we’ve crossed a threshold in our climate system where nonlinear effects are starting to play a role. If so, the likelihood of such events has become much greater. This, he says, needs to be studied further.

One thing is certain: the heat of intensity being felt in the western United States right now is killer. In the recent Pacific Northwest heat wave alone, several hundred people died, and the numbers continue to rise. On average, heat waves kill more people in the United States than any other type of extreme weather.

Each year, around 500,000 deaths are attributed to extreme heat, and a recent study found that more than a third of heat-related deaths are due to the impact of climate change.

There is unanimous agreement in the climate science community that heat waves will become more frequent and intense as we continue to heat the planet. We cannot call what we see today “the new normal” because it will continue to get worse.

But scientists also point out that we know how to solve this challenge and that we have the tools to do it: stop burning fossil fuels and temperatures will stop rising. All that’s missing, they say, is the political will to make this happen at the pace needed to avoid catastrophic impacts.