Human-caused climate change made last week’s deadly heat wave in England and Wales at least 10 times more likely and added a few degrees to the brutality of the heat, a study has found.
A team of international scientists has found that the heat wave that set a new national record at 104.5 degrees Fahrenheit was made stronger and more likely by the buildup of heat-trapping gases from burning coal, petroleum and natural gas.
They said on Thursday that temperatures were 3.6 to 7.2 degrees warmer during the heat wave than they would have been without climate change, depending on the method the scientists used.
The study has yet to be published in a peer-reviewed scientific journal, but follows scientifically accepted techniques, and such earlier studies have been published months later.
“We wouldn’t have seen temperatures above 104 degrees in the UK without climate change,” lead study author Friederike Otto, a climatologist at Imperial College London, said in an interview. “The fingerprint is super strong.”
World Weather Attribution, a collection of scientists around the world who conduct real-time extreme weather studies to see if climate change played a role in an extreme weather event and, if so, to what extent, examined the two-day average temperatures for July 18 and 19 across much of England and Wales and the highest temperature reached at that time.
The highest daily temperatures were the most unusual, a once-in-1,000-year event in today’s warmer world, but “almost impossible in a world without climate change”, according to the study.
Last week’s heat broke the old national record of 2.9 degrees. The average over two hot days and nights is an event that happens once a century now, but is “almost impossible” without climate change.
When scientists used England’s long temperature history to determine the impact of global warming, they found a stronger influence of climate change than when they used simulations from climate models. For some reason that scientists aren’t entirely certain about, climate models have long underestimated extreme summer weather signals in western Europe, Otto said.
With climate models, scientists simulate a world without the 2.2 degrees of warming since pre-industrial times and see how likely that heat would have been in this cooler world without the warming from fossil fuels. With observations, they look at history and calculate the chances of such a heat wave in this way.
“The methodology seems solid, but frankly, I didn’t need a study to tell me it was climate change,” said Marshall Shepherd, a professor of meteorology at the University of Georgia, who doesn’t was not part of this study team, but was part of a US National Academy of Science Panel that has declared these types of studies to be scientifically sound. “This new era of heat is particularly dangerous because most homes are not equipped with it.”
The World Weather Attribution study points to another analysis which estimates that a heat wave like this would kill at least 800 people in England and Wales, where there is less air conditioning than in warmer climates .
Otto, who had to sleep and work in the basement because of the heat, said as the world warms these record-breaking heat waves will continue to occur more frequently and hotter.
As well as urging people to reduce greenhouse gas emissions, study co-author Gabe Vecchi said: “This heatwave and heatwaves like this should remind us that we have to adapt to a warmer world. We no longer live in the world of our parents.