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Britain’s freakish heat demolished records. Here’s what happened.

The magnitude and extent of Tuesday’s record temperatures underscored the exceptional nature of the European heat wave

The record-setting temperature in Coningsby, England, compared with the previous 50 years. (Robert Rohde/Berkeley Earth)
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The maximum temperature reached Tuesday in Coningsby, England — 130 miles north of London — was unlike anything the village had ever observed. It was an outlier in the truest sense: about 9 degrees Fahrenheit (5 degrees Celsius) above the previous highest temperature.

That high temperature, 104.5 degrees (40.3 Celsius), shattered the national temperature record for Britain by a lofty 2.9 degrees (1.6 Celsius).

Ordinarily, when temperature records are broken during heat waves, they do so in a few places and by fractional degrees. But on Tuesday, records in the United Kingdom toppled over a vast area and by enormous margins.

The magnitude and extent of Tuesday’s temperatures underscored the exceptional nature of this extreme event — which scientists say would have been impossible without a boost from human-caused climate change.

Why this European heat wave is so scary

The most impressive records set

As Coningsby set the national temperature record for England and the United Kingdom, all-time highs were also set in Scotland and Wales:

  • Hawarden, Wales, hit 98.8 degrees (37.1 Celsius)
  • Floors Castle, Scotland, hit 95.2 degrees (35.1 Celsius)

England, Wales and Scotland also established their highest minimum (nighttime) temperatures ever recorded. At London’s Kenley Airport, the record-setting low was a tropical 78.4 degrees (25.8 Celsius).

At least 34 locations in the U.K. set new all-time records, the U.K. Met Office reported, five of them exceeding 40 Celsius (104 degrees).

Numbers and charts help tell the story of the scorching heat, and many shared by experts and climate scientists during the record day illustrate how remarkable it was.

The long-term time series of the U.K.'s highest temperatures, below, illustrates just how hot Tuesday was compared with the past. The chart also shows a trend toward more of these hot days, particularly in the past several decades:

As the United Kingdom has maintained temperature records over a longer period than any country in the world, Ed Hawkins, a climate scientist at the University of Reading, plotted temperatures averaged over Central England from 1772 to present. Tuesday sticks out like a sore thumb:

Just how out of whack were London’s temperature Tuesday? Robert Rohde, a climate scientist at Berkeley Earth, prepared the chart below, showing Tuesday’s 104.4 degrees (40.2 Celsius) far, far off the normal distribution:

It was not only exceedingly hot where people live, but also at high altitudes.

In a tweet, atmospheric scientist Philippe Papin showed that temperatures a mile up were about four standard deviations from the norm over a vast area of the United Kingdom, meaning it had about a 0.1 percent chance of happening:

While the U.K. was home to the most widespread records amid this European heat wave, Wednesday produced more remarkable heat in other spots across the continent.

Brutal heat dome moves east, with Central Europe sweltering

As scores of all-time heat records were set in Germany on Wednesday, Hamburg crossed the 40 Celsius (104-degree) threshold for the first time ever observed — the location farthest north in the country to do so on record. Hamburg (53.5 North latitude) is even farther north than London (51.5 degrees North) and at about the same latitude as Edmonton, Canada.

What made it so hot?

The heat originated from a sprawling zone of high pressure known as a heat dome. It spread historically high temperatures over the Iberian Peninsula late last week before shifting into Germany and Denmark on Wednesday. Underneath these heat domes, the air sinks, clearing out cloud cover while allowing the sun to beat down relentlessly.

The high-pressure zone ballooned unusually far north into Europe due to a low-pressure system west of Portugal, whose circulation pumped in hot air from northern Africa.

The high-pressure zone that formed the heat dome was part of a sequence of seven alternating high- and low-pressure systems circling the northern hemisphere — known as a wave train or, more specifically, a “wavenumber-7 pattern.” The pattern is known for supporting intense and persistent heat waves.

The presence of so many waves set up an atmospheric traffic jam of sorts, slowing down the flow of these systems, allowing heat to build. Other heat waves were simultaneously affecting the central United States and central Asia.

Extreme heat prompts alerts in 28 states as Texas, Oklahoma hit 115

Research published by Michael Mann, a climate professor at Penn State University, and colleagues links an increase in such patterns to human-caused warming of the Arctic. In an email, Mann confirmed the presence of such a pattern this week.

How this compares with the past

The U.K. has endured brutal heat waves in the past, some more prolonged than this year’s, but none have been nearly as intense.

The hottest summer on record in the U.K. occurred in 1976, with heat so extreme it has remained entrenched in the national psyche. The U.K. saw 15 consecutive days of temperatures above 90 degrees (32 Celsius). Mortality rose 20 percent above baseline levels. But the maximum temperature was a mere 96.6 degrees (35.9 Celsius).

The infamous 2003 heat wave, blamed for 70,000 deaths in western and central Europe, saw the mercury soar to 101.3 degrees (38.5 Celsius) in the U.K., a record at the time. But it was surpassed 16 years later by the 2019 heat wave, which saw the mercury reach 101.7 (38.7 Celsius) in Cambridge. The most recent heat wave toppled that with ease.

The below chart shows that nine of the U.K.'s 10 hottest days on record have occurred since 1990 — with Thursday far above the rest of the pack.

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