Climate change may amplify the lethal effect of weather conditions that have brought intense heat waves to Europe in the past.
Being ready is the mantra we often hear in relation to future pandemics. This time, however, it concerns another subtle threat: the one represented by the next heat waves over Europe.
Based on a study published in Nature Climate Changeif the same meteorological conditions that gave rise to the worst heat waves of the last 30 years in the Old Continent were to recur now, in the current global warming situation, they would cause an exaggeratedly high number of deaths.
European healthcare systems – the analysis points out – are not ready to deal with similar situations and we need to take action.
The same events in a worse context
Historically, the deadliest heat waves in Europe occurred during a phenomenon known as a “heat dome”, the stalling of a high-pressure system (an atmospheric zone in which the weight and pressure of the air is greater than surrounding areas, associated with good, stable weather) over an area already suffering from months of low rainfall and drought. This system acts like the lid of a pot and traps the hot air underneath for a long time.
In the summer of 2003, a phenomenon of this type maintained temperatures of around 38°C for at least two weeks straight across much of Western Europe, from Finland to Poland, producing a heat wave so extreme that it caused, according to estimates by the French National Institute of Health and Medical Research, more than 70,000 deaths in 16 European countries.
The torrid summer of 2003 also caused a loss of 10% of the total size of European glaciers, decimated agricultural and animal feed production, and generated serious critical issues in the energy production chain.
The point is that the conditions that produced this and 4 other severe heat waves in Europe in the past could return. But they would do so in a much warmer climate, which hovers on the threshold of +1.5°C of global warming since the pre-industrial era, and which has average annual temperatures 0.7°C higher than the 2003 average.
There is a limit to the ability to adapt
Scientists at the Stanford Doerr School of Sustainability pulled together weather data, daily surface temperature readings and death certificates from 924 European subregions collected in five severe heat waves between 1994 and 2023. They then compared them with data on global average temperatures from the 12 months preceding each heat wave to try to understand how much human influence on the climate had affected the conditions of the heat wave that was about to be unleashed.
The analysis revealed a sharp increase in deaths due to excess heat after a day at 30°C, even in the habitually warmer regions, a finding that suggests it is a limit to the ability to adapt to the heat. Furthermore, mortality risk is closely linked to the temperatures to which a location is accustomed – typically colder places are more sensitive to the effects of heat waves.
“We are not comparing Paris with Armsterdam, but Paris with itself during August 2003 and a normal August 2002,” explains Marshall Burke, Professor of Global Environmental Politics and one of the authors of the study. “This allows us to isolate the impact of heat from all the other factors that could affect mortality.”
A budget similar to that of the covid era
Burke and colleagues estimated that, with the amount of heat retained in the atmosphere today by greenhouse gases emitted by human activities, weather conditions similar to those of summer 2003 could cause 17,800 additional deaths in Europe in a single week (compared to the 9,000 that would have occurred without the effect of global warming caused thus far).
In an unfavorable context of +3 °C, weekly excess deaths could reach 32,000 – bulletins that recall those released in the most dramatic weeks of the Covid pandemic.
We are not prepared: if the pace of adaptation to heat waves followed those adopted so far, in the future we could only prevent one in 10 deaths due to extreme heat. We need to understand which prevention strategies are most effective – whether, for example, programs to assist the most isolated people or to increase ventilation in schools or shading in cities – and prepare hospitals and health systems for worst-case scenarios. So that an explosive event like those described, rare but possible, does not cause deaths Also due to the disorganization and saturation of services, as happened in the pandemic.
