An extra 2.3 million people in European cities could die as a result of extreme temperatures — both hot and cold — by the end of the century if countries do not take action to mitigate climate change, according to a study that modelled the effects of rising temperatures.

Researchers analysed temperature and mortality data from 854 urban areas across 30 European countries to project possible temperature-related deaths between 2015 and 2099. They explored various warming scenarios and considered the effects of strategies to to keep people safe amid rising heat, such as increasing the amount of green space and shade in cities or installing air conditioning in homes.

The results, published in Nature Medicine¹, suggest that heat-related deaths will surpass those caused by cold conditions in even the most optimistic scenarios, and that temperature-related deaths overall could increase by nearly 50%. Mediterranean regions, particularly eastern Spain, southern France, Italy and Malta, are on track to be the worst affected (see ‘Deadly heat’).

“We would need a massive adaptation in order to compensate for the increase in temperature,” says study co-author Pierre Masselot, a statistician and environmental epidemiologist at the London School of Hygiene & Tropical Medicine. At the moment, he says, “it’s difficult to see how that level of adaptation could be reached”.

Rapid warming

In recent years, several countries have experienced record-breaking heatwaves that have been linked to tens of thousands of deaths². Still, in Europe, deaths due to cold temperatures currently outnumber those caused by heat by ten to one. This is on track to change as global temperatures increase: cold-related deaths are projected to fall, while those caused by extreme heat will become more prevalent.

For their analysis, Masselot and his colleagues explored four future scenarios in which global temperatures increase by 1.5 °C, 2 °C, 3 °C and 4 °C. They also considered three scenarios for how countries might improve their adaptation strategies, potentially reducing the risk of heat-related deaths by 10%, 50% or 90%.

How climate change is hitting Europe: three graphics reveal health impacts