Western Europe's Extreme Heat Wave 'Virtually Impossible' Without Climate Change, Scientists Say

BRUSSELS — This week’s extraordinary heat wave is the worst to ever hit Western Europe and could not have occurred without humans heating the planet by burning fossil fuels, scientists say.

Europeans from Spain to the United Kingdom have been sweltering under extreme heat this week, with temperatures surging to near or above 40 degrees Celsius even before peak summer takes hold.

New research published Friday finds that this kind of event would have been "virtually impossible" just 50 years ago, and has become vastly more likely even over the past two decades due to global warming.

The World Weather Attribution consortium, which includes scientists from Imperial College London and the Red Cross Red Crescent Climate Centre, used peer-reviewed methods to compare this week’s heat wave to other hot European summers in 1976 and 2003.

"Over the full extent of this heat wave, we found that in the last 50 years … the chance of a heat wave like this has changed immensely," said lead author Theodore Keeping, an extreme weather researcher at Imperial College London.

"This event would not have been possible in June without climate change," he added. "The three-day [average] nighttime temperatures would not have been possible at any time of year without climate change, and the chance of the three-day maximum daily temperatures like this occurring at any time of the year has increased by over 500 times" since 1976.

By 1976, the planet had heated by just 0.3 C above preindustrial levels, rising to 0.6 C in 2003 and 1.4 C last year. There is scientific consensus that heat waves are becoming more frequent and hotter with every fraction of a degree.

For the large Western and Central European region analyzed — which ranges from northern Spain and the U.K. into southern Sweden and eastern Poland — "this heatwave is the most severe ever recorded," the scientists wrote.

The scientists also say that the daytime temperatures seen this week are now 10 times more likely to occur than during the brutal 2003 summer, when 70,000 people died from heat-related causes. This week’s high nighttime temperatures are even around 100 times more likely than they were 23 years ago.

Higher heat, higher humidity

Climate change also made this event hotter. "A similar heat wave in June would have been about 3.5C cooler during the day in 1976 and about 2C cooler in 2003," said Keeping. "The nighttime temperatures would have been about 2.4C cooler in 1976 and about 1.3C cooler in June 2003."

Besides comparing past temperatures across the wider Western European region, the scientists also looked at around 850 European cities and found that some 45 percent had broken their all-time "wet-bulb" temperature record.

Wet-bulb measurements combine dry heat temperature and humidity, and are used to assess the impact of heat on human health as they mimic the body’s ability to cool itself through sweating.

The record-smashing values suggest that "the health impacts of this heat wave are likely to be extremely high," Keeping warned.

On top of that, many European capital cities are experiencing the hottest three-day period since 1950, when reliable record-keeping started.

"Due to global warming, these very high temperatures are now expected regularly during summer months in many capitals," Keeping said.