The record-crushing temperatures in the Pacific Northwest are mind-blowing: 116 degrees in Portland. 118 degrees in British Columbia. 108 in Seattle.

It’s so hot that streetcar power cables are searing in Portland and pavement is buckling in western Washington.

Many have expressed shock about this unprecedented heat wave. Yet the writing has been on the wall for decades.

Since the 1970s and 1980s, climate scientists have warned that global warming would make heat waves more frequent, long-lasting and intense. Maybe it’s only now that the reality is hitting home.

A heat wave is pushing temperatures to record highs in the northwestern United States and western Canada. (Christopher Vazquez/The Washington Post)

40 years of warnings

More than three decades ago, in his seminal study predicting the course of human-caused climate change, NASA scientist Jim Hansen wrote that “temperature changes within several decades will become large enough to have major effects on the quality of life for mankind in many regions.”

Hansen used the analogy of “loaded dice” to describe how climate change would increase the likelihood of extremely hot weather in a given year while decreasing the chance of unusually cold weather.

Even before that, in 1979, the National Research Council published a study led by the late meteorologist Jule Charney that predicted serious global warming would evolve. “It appears that the warming will eventually occur, and the associated regional climatic changes so important to the assessment of socioeconomic consequences may well be significant,” the report said.

Since those prescient projections 30-to-40-plus years ago, heat waves all over the world have intensified. Heat domes, the sprawling zones of high pressure at high altitudes that essentially bake the air underneath them, have strengthened.

During the European heat wave in 2003, blamed for 70,000 deaths, the average temperature was higher than any year since at least 1851. A study published in 2004 found human influence “at least doubled the risk” of a heat wave of that magnitude.

By 2010, when a historically intense heat wave killed 50,000 people in Russia, the risk of such an event was tripled due to climate change, according to a study published in 2012.

In 2016, a report from the National Academies of Sciences concluded that of the connections between human-caused climate change and extreme weather events, heat waves had among the most straightforward ties.

Chickens coming home to roost

Over the last few summers, hot weather extremes have pushed past historic thresholds all over the globe.

The summers of 2016 and 2017 brought the highest recognized temperatures in 76 years when the World Meteorological Organization certified highs of 129 degrees in Mitribah, Kuwait, and 128.7 degrees in Turbat, Pakistan. At the time, they ranked as the third and fourth highest temperatures ever measured.

The Northern Hemisphere was swarmed by record-setting during the summer of 2018. All-time high temperatures were set in Southern California, Scandinavia, Eurasia, Japan and the Middle East. Death Valley, Calif., registered the hottest month ever observed on the planet that July.

A study published in the journal Earth’s Future after that summer found exceptional heat affected 22 percent of the populated and agricultural areas of the Northern Hemisphere between May and July. It concluded that the planet had entered “a new climate regime,” featuring “extraordinary” heat waves on a scale and ferocity not seen before.

The summer of 2019 then brought another extraordinary heat wave to Europe, which broke some of the records set in the notorious 2003 event. For example, Paris hit an all-time high of 108.7 degrees. Germany, Belgium and the Netherlands posted new national temperature records.

“Over France and the Netherlands, such temperatures would have had extremely little chance to occur without human influence on climate,” concluded an analysis published after the event.

The mercury spiked again last summer. In June, the temperature eclipsed 100 degrees inside the Arctic Circle for the first time ever recorded. An analysis found that the record-breaking heat in Siberia during the first half of the year was made at least 600 times as likely by climate change.

That same summer, Death Valley soared to 130 degrees in August, ranking among the top-three highest temperatures ever measured on the planet, surpassing the marks set in Mitribah and Turbat in 2016 and 2017. Numerous locations in the West saw their highest August temperatures ever observed, which presaged California’s most devastating wildfire season on record.

The intensity of the heat so far this summer appears to be raising the bar. The mid-June heat wave that scorched the zone from California through the Desert Southwest and Rocky Mountains set nearly 4,000 records. Phoenix hit at least 115 degrees for a record six days in a row, and Tucson topped 110 for a record eight straight days.

“[A]ll-time maximum temperature records fell at locations in seven different states,” wrote Climate.gov.

That heat wave expanded into Mexico, where a location just south of the U.S. border soared to 124.5 degrees, the highest temperature ever recorded in the country during June.

Only days later, a historic heat wave hit Eastern Europe and Russia, setting June temperature records in several countries and numerous population centers, including Moscow, where it was 95 degrees.

Now, we’re in the midst of the most severe heat wave in the history of the Pacific Northwest, with temperatures up to 40 degrees above normal.