Scientists Say Record-Shattering European Heat Wave Made 'About 100 Times More Likely' by Climate Crisis

The heat wave that smashed records across Western Europe last week was made much more likely and intense by the human-caused climate emergency, according to a new analysis released Friday.

"The July 2019 heat wave was so extreme over continental Western Europe that the observed magnitudes would have been extremely unlikely without climate change."
--WWA reportThe report (pdf) comes from the World Weather Attribution (WWA), an international partnership that brings together researchers from universities and other prominent institutions to examine the possible influence of the climate crisis on various extreme weather events.

"It is noteworthy that every heat wave analyzed so far in Europe in recent years (2003, 2010, 2015, 2017, 2018, June 2019, and this study) was found to be made much more likely and more intense due to human-induced climate change. How much more depends very strongly on the event definition: location, season, intensity, and durations," the report explains. "The July 2019 heat wave was so extreme over continental Western Europe that the observed magnitudes would have been extremely unlikely without climate change."

Jan van Oldenborgh of the Royal Netherlands Meteorological Institute, who contributed to the study, called the July heat wave "unprecedented" in terms of scale and intensity.

"We find that it was much more extreme than any other heat wave we've looked at over the last few years," van Oldenborgh told Carbon Brief. "[It impacted] France, Luxembourg, Belgium, the Netherlands, Western Germany, Eastern England, and also parts of Scandinavia--and at the moment it's inducing a large melting event over Greenland."

Examining specific countries impacted by the scorching heat last week, researchers found that "over France and the Netherlands, such temperatures would have had extremely little chance to occur without human influence on climate," appearing less than every 1,000 years. In France, the report says, the climate crisis made extreme heat "about 100 times more likely."

Researchers also found that while such high temperatures are less rare in the United Kingdom or Germany, they were still made three to 10 times more likely by the climate crisis. Across all countries, the report says, "an event like the observed would have been 1.5 to 3degC [34.7 to 37.4degF] cooler in an unchanged climate."

Lead author Robert Vautard of the Institut Pierre-Simon Laplace in France toldThe Associated Press Friday that "this will go up and if we don't do anything about climate change, about emissions, these heat waves which today have an amplitude of 42 degrees, they will have three degrees more in 2050 so that is going to make 45 (degrees) roughly speaking."

Vautard added that WWA's latest heat wave analysis should serve as a signal about what the future could hold. "What will be the impacts on agriculture? What will [be] the impacts on water?" he said. "This will put [real] tension in society that we may not be so well equipped to cope with."

"These records will be broken in few years... What we see with European heat waves is that all the climate models are underestimating the change that we see."
--Friederike Otto, University of OxfordFriederike Otto of the U.K.'s University of Oxford, who also contributed to the WWA report, toldThe Guardian Friday that although the heat wave was regarded as historic when it happened last week, "it will not make history."

"These records will be broken in few years," she warned. "What we see with European heat waves is that all the climate models are underestimating the change that we see."

Van Oldernborgh, in his interview with Carbon Brief, said that "we really need to do a lot more serious research than we can do within one week to look at why there is such a big discrepancy between the observed trends and the modeled trends."

"But heat waves are very special," he added. "A lot of things come together for a heat wave--heat from the Sahara, local heating due to sunshine, the reaction of vegetation due to very hot conditions--and all these things have to be modeled right. I'm just afraid that these models that have been designed to project the average climate correctly cannot handle these very extreme situations very well."

Looking ahead, the report says that "heat waves during the height of summer pose a substantial risk to human health and are potentially lethal. This risk is aggravated by climate change, but also by other factors such as an aging population, urbanization, changing social structures, and levels of preparedness. The full impact is only known after a few weeks when the mortality figures have been analyzed. Effective heat emergency plans, together with accurate weather forecasts such as those issued before this heat wave, reduce impacts and are becoming even more important in light of the rising risks."

The extreme heat that struck Europe last week--before moving on to Greenland, where it caused massive ice melt--was part of what the World Meteorological Organization announced Thursday could the hottest month in the planet's recorded history. The soaring temperatures in July came after multiple analyses concluded the previous month was the hottest June ever documented.