How hot can a heat wave really get? Before June 2021, scientists thought they knew.
That’s when one of the most extreme heat spikes ever observed hit western North America, leaving at least 1,400 people dead. Lytton, British Columbia, smashed the 84-year-old Canadian heat record on June 26, reaching 46.6 C (116F).
And it smashed that the next day by 1.3C.
And smashed that the next day by another 1.7C.
And the next day, Lytton burned to the ground.
When a team of climate scientists assembled days later to analyze the heat wave, they found that the local historical weather data offered a paradox: Their standard approach for estimating a heat wave’s rarity concluded that the new records were too extreme to occur in the region where they actually did. They were in a sense “impossible” even though they actually occurred, as three American scientists put it earlier this year.
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They adjusted their method to accommodate the new reality (and use that approach still), but noted that “follow-up research will be necess…