European cities face millions more deaths from extreme temperatures

There will be an extra 2.3 million temperature-related deaths in Europe’s main cities by 2099 without more action to limit warming and adapt to it, researchers predict. However, in cities in colder northern countries such as the UK, there will be fewer temperature-related deaths over this period, because the decline in deaths from cold will be greater than the increase in deaths from heat.

“We estimate a slight net decrease, but it’s very small compared to the big increase we could see in the Mediterranean region,” says Pierre Masselot at the London School of Hygiene & Tropical Medicine.

Masselot’s team started by looking at epidemiological studies on how deaths increase during periods of extreme heat or extreme cold. His team then used these statistical links to estimate how the number of excess deaths would change over the next century in various warming scenarios.

The study looks at 850 cities – home to 40 per cent of Europe’s population – but not any rural areas. This is because the statistical links are stronger where lots of people live in a small area and are exposed to roughly the same conditions.

If cities don’t adapt, the net effect of climate change increases exponentially with greater warming. In a scenario similar to our current course, the number of excess deaths related to temperature would increase by 50 per cent, from 91 per 100,000 people per year in recent years to 136 per 100,000 people per year by 2099.

Adaptive measures such as the wider use of air conditioning and planting more trees in inner cities would bring these numbers down, says Masselot, but to significantly reduce a population’s vulnerability to heat requires substantial adaptive measures. “This is much more than what we have already observed in many countries across the world.”

The team's estimates are based on the average daily temperatures in warming scenarios, and they don't include the possibility of much more extreme heatwaves. "We have found that usually this is good enough to be able to relate deaths to temperature," says Masselot.

This is the most comprehensive study of its kind so far, he says. It includes more countries and suggests for the first time that even France and Germany will have more temperature-related deaths as the continent warms.

Rising temperatures will have a wide range of effects on people, from their health to their productivity, he says. "Mortality is just one part of the story."