This past summer, parts of Europe experienced record-breaking heatwaves during the fourth-hottest summer in the continent’s history. The extreme heat affected critical infrastructure like rail tracks, triggered wildfires, and killed thousands.
But it wasn’t the worst the continent has seen. The summer of 2003 was the hottest summer on record. And a new study analysed the conditions of past heatwaves like the one in 2003, to see how similar weather patterns would play out in today’s warming climate.
A look at the past
The 2003 heatwave killed more than 20,000 people across Europe. During that time, Spain, Italy, and France were hit especially hard.
For two weeks, temperatures were around 38 degrees Celsius across much of Western Europe. The United Kingdom also experienced one of its hottest summers on record.
The temperatures were extreme, and it was believed to be a “one-in-a-million-year event.” But climate change makes a similar event even more likely.
“That event, which was devastating from a health point of view, was extremely statistically rare at the time that it happened, and yet we know it’s possible the weather conditions that produced it could happen again, but in what is now a much warmer climate,” said co-author Noah Diffenbaugh, the William Wrigley Professor in the Stanford Doerr School of Sustainability.
Applying history to the present
In the study, which was published in the journal Nature Climate Change, researchers used artificial intelligence and statistics to estimate what would happen if the 2003 conditionsoccurred again with today’s average temperatures.
Global average temperatures are about 0.7 degrees above the 2003 average, and approaching 1.5 degrees Celsius above pre-industrial levels. The study analysis found that in today’s climate, 2003-like weather patterns would cause 17,800 excess deaths across the continent in a single week. With no global warming, the excess death toll would be about 9,000.
Researchers also assessed how the death toll would change at 3 degrees Celsius above pre-industrial levels. Heatwaves could cause 32,000 excess deaths in these conditions.
“These events could be as bad as some of the worst weeks of COVID by mid-century,” said co-author Marshall Burke, a Stanford professor of environmental social sciences.
How can we prepare?
Climate change is already increasing the frequency and intensity ofextremeheat events. In Europe, heatwaves come after high-pressure systems called “heat domes” form over areas that haven’t experienced much precipitation. With more heat in the atmosphere, these events will get worse and kill more people.
“We showed that if these same weather systems [as 2003] were to occur after we’ve trapped a lot more heat in the atmosphere with greenhouse gases, the intensity of the heatwaves gets stronger and the death toll rises,” said lead study author Christopher Callahan, who completed the research as a Stanford Doerr School of Sustainability postdoctoral scholar.
The authors emphasise that we need to prepare for such extremes. They stress that more research is needed to find effective heat interventions and adaptations, such as air conditioning, increasing ventilation, and implementing more shade. Hospitals and health systems can also prepare through capacity building.
“If novel or faster adaptations emerge, these death tolls could be reduced more,” said Callahan.