Climate change exacerbated Britain’s heat wave, scientists find

Climate change exacerbated Britain’s heat wave, scientists find

The heat that destroyed records in Great Britain last week it would have been “extremely unlikely” without the impact of human-induced climate change, a new scientific report released Thursday finds.

The heat from last week’s intensity is still highly unusual for Britain, even at current levels of global warming, said Mariam Zachariah, a research associate at Imperial College London and lead author of the new report. The odds of seeing the daytime spikes that some parts of the country registered last week were 1-in-1,000 in any given year, she and her colleagues found.

Still, said Dr. Zachariah, those temperatures were at least 10 times more likely than in a world with no greenhouse gas emissions, and at least 3.6 degrees Fahrenheit hotter.

“It’s still a rare occurrence today,” said Friederike Otto, a climate scientist at Imperial College London and another author of the report. “Without climate change, it would have been an extremely unlikely event.”

Severe heat has become more frequent and intense in most regions of the world, and scientists have no doubt that global warming is a major driver. As the burning of fossil fuels causes the average temperature on Earth to rise, the range of possible temperatures also shifts upward, increasing the likelihood of blistering peaks. This means that any heat wave is now exacerbated to some degree by changes in planetary chemistry caused by greenhouse gas emissions.

Before last week, the highest temperature Britain had ever recorded was 101.7 Fahrenheit or 38.7 Celsius, a milestone reached in Cambridge in July 2019. warned Brits to brace themselves for new highs.

The mercury blew past the old record on the morning of July 19 in the village of Charlwood, Surrey, and continued to rise. By the end of the day, 46 weather stationsSpanning most of England from London in the south east to North Yorkshire in the north east, it had recorded temperatures reaching or exceeding the previous national record. Other stations broke their own local records by 5 to 7 degrees Fahrenheit.

In response, trains were slowed down for fear that the heat could cause the steel rails to collapse. Grass fires spread to homes, shops and vehicles in London in what the city described as the busiest day of firefighting since World War II. More than 840 more people may have died in England and Wales than would normally have been, according to preliminary analysis using peer-reviewed methodology.

Last week’s heat report was produced by World Weather Attribution, an alliance of climate scientists specializing in rapid studies of extreme weather events to assess how far global warming was behind it. Using computer simulations, the scientists compare the existing world, in which humans spent more than a century adding heat-trapping gases to the atmosphere, to a world that could potentially have existed without that activity.

The group’s analysis of the heat in Britain has not yet been peer-reviewed or published in an academic journal, but it is based on peer-reviewed methods.

Using similar techniques, the group found that the heat wave that roasted south asia this spring was 30 times more likely due to global warming.

A lot of Western and Central Europe had a very hot summer start, driven by a high pressure area bringing warm air from North Africa. England has its driest July in over a century. When the ground has dried out, the sun’s energy goes toward heating the air rather than evaporating water on the ground, which can contribute to even higher temperatures.

Scientists reported this month that heatwaves in Europe grown in frequency and intensity over the past four decades, at least in part because of changes in the jet stream.

For some scientists, the recent heat in Britain was reminiscent of last summer’s deadly temperatures in the Pacific Northwest, breaking records in places of 7 degrees Fahrenheit or more. That heat was so unusual that some climate researchers wondered if hot extremes appeared faster than their scientific models calculated. It was the climate equivalent, said Erich Fischer of Swiss University ETH Zurich, of an athlete who beat the long jump record by 2 or 3 feet.

So far, however, the evidence suggests that such events are surprising but not unforeseeable using current models. dr. Fischer led a study last year that showed that global warming, with its seemingly small increases in average temperatures, also increases the likelihood of shattering heat records by large margins.

As with floods, droughts and other extremes, the question is whether policymakers will use this knowledge to better prepare in advance.

“There are circumstances that usually turn these hazards into disasters, and these conditions are man-made,” said Emmanuel Raju, an associate professor of public health at the University of Copenhagen and another author of the report on Britain’s heat. These conditions include poor planning and lack of consideration for vulnerable groups such as the homeless, said Dr. raju.

Vikki Thompson, a climate scientist at the University of Bristol, led another recent study that found that while extreme heat has become more common worldwide in recent decades, most of it could still be explained by higher average temperatures due to climate change. “They are increasing in intensity, but not faster than the average,” said Dr. Thompson.

But even this rate of increase is putting a strain on countries’ ability to cope. The British Rail System is designed to only operate safely up to 80.6 degrees Fahrenheit. Most homes are designed to retain heat during frigid winters. Many Brits still see warm weather as a welcome relief from the cold and damp.

In Britain “people still don’t take it as seriously as they might next time,” said Dr. Thompson. “A heat wave is seen by most people as something wonderful to experience. They want some warmth.”

“But when it’s 40 degrees,” or 104 Fahrenheit, she said, “that starts to change.”