Parisians are most at risk of dying in European heatwaves

Among European capitals, Paris has long been regarded as the epitome of elegance, culture and romance. But beneath its picturesque façade lies a simmering danger that threatens its bustling population.

Paris is the most vulnerable capital in Europe when it comes to heatwaves. Its population faces the highest risk of heatwave-related deaths, according to an article recently published in The Lancet journal.

Researchers from various countries in Europe studied mortality risks due to heat and cold across 854 cities from 2000 to 2019. The findings were unequivocal. Paris topped the list in heat-related risk across all age groups, with a likelihood of excess deaths due to rising temperatures 1.6 times higher than other European cities. Amsterdam and Zagreb followed closely behind.

With the advent of rising temperatures due to climate change, Paris is bound to continue feeling the heat. By 2050, the city could reach temperatures of up to 50°C.

Urban heat island effect

Pinpointing the exact reason behind the vulnerability of Paris’s population when it comes to heatwaves is a complex task. “It’s difficult to isolate specific factors,” says Dr. Pierre Masselot, author of the study and researcher at the London School of Hygiene & Tropical Medicine. “The sheer size and density of the city definitely contribute to the heightened risk,” he says, explaining that with a population of over 2 million, the effects of heatwaves are amplified.

The socioeconomic standing of the city’s population is also an important variable to consider. “Being a big city, Paris has more disadvantaged inhabitants too,” says Masselot. Low-income neighbourhoods with limited access to green spaces, shade and air-conditioning bear the brunt of extreme heat, exacerbating the threat to vulnerable communities. “Add to this the fact that these communities often have higher rates of pre-existing health issues, and it becomes clear why” there is a greater risk to them, he says.

What is known as the “urban heat island effect” compounds the city’s deadly predicament. These hot spots occur when cities become significantly hotter than surrounding rural areas, primarily due to the proliferation of buildings and materials that absorb and retain heat. Paris’s famous grey rooftops are one example of this. While revered by famous painters like Vincent Van Gogh, the grey rooftops are made of zinc – a metal that absorbs heat. “The same goes for tarmac, which stores [and] then releases heat, making it more difficult for the city to cool down at night,” says Masselot. “And the presence of buildings blocks wind.”

Though the heat island effect can turn Paris into a veritable cauldron, temperature disparities exist from neighbourhood to neighbourhood. “Going from a dense industrial area to a park, for example, you can feel a significant drop,” Masselot explains.

Pollution also plays a significant role in Paris's vulnerability to heatwaves. Largely generated by vehicle emissions, air pollution creates a “sort of greenhouse effect” that traps heat and intensifies extreme temperatures. “Exhaust fumes are darker and therefore reduce the city’s albedo (the proportion of incoming solar radiation reflected by the various surfaces in the urban environment), storing more heat,” the researcher explains.

And then there is the fact that heatwaves have been historically less common in Paris than other European capitals like Madrid, for example. “Cities used to heatwaves have adapted to them,” says Masselot. “So in Madrid, the mortality risk is slightly lower than in Paris for the same temperature.”

Lessons from a deadly summer

The summer of 2003 etched a harrowing chapter in European history. A heatwave of unprecedented magnitude swept across the continent, leaving a trail of devastation in its wake. More than 70,000 people died as a result, with over 15,000 of those deaths recorded in France alone. Temperatures in Paris climbed above 40°C for weeks on end.

The healthcare system was overwhelmed, with hospitals struggling to cope with the influx of patients suffering from heatstroke and dehydration. Public authorities were completely unprepared and were later criticised for their reluctance to attribute heat as the primary cause of death. France's director-general for health at the time, Lucien Abenhaim, handed in his resignation due to the “controversies surrounding the handling" of the deaths "connected with the heatwave”. A state of emergency was declared, allowing patients to be sent to military hospitals and for crisis morgues to be established to handle the influx of bodies.

Those most affected were the elderly. Half of those who died were over the age of 85 years old, and 92% of the victims lived in isolation, many without family, friends or social ties to claim their bodies. “It opened a lot of people’s eyes,” says Masselot. “It was a turning point for the whole continent.” Some climatologists even called the heatwave the “ground zero of global warming”.

The magnitude of the tragedy prompted a collective awakening, marking a pivotal moment for the French government to take proactive measures to protect its citizens. Paris took significant strides to combat the escalating threat of heatwaves and implemented measures to avoid another disaster.

Since then, authorities have created a heatwave plan. Information on best practices is dispersed across the city, with posters detailing what to do in case of extreme heat. A telephone hotline has been set up by the city so that vulnerable people in isolation are called regularly by authorities, who check in to ensure their state of health is adequate. "Cool islands" – oases of relief from sweltering temperatures – located in museums, libraries, swimming spots, and green spaces have been created.

A Climate Action Plan was created in 2018, with Paris Mayor Anne Hidalgo at its head. Reducing vehicle traffic during heatwaves was noted as a key strategy. The mayor promised that by 2030, police would prevent the vehicles that pollute the most from being driven in the city during peak heat periods.

The plan outlined ways of improving building insulation and ventilation, changing construction guidelines that are adapted to the consequences of climate change like surging summer heat. It also set out to revolutionise Parisian roofs, stating that by 2050 all roofs must “produce at least one” of the following resources: renewable energy with solar panels, food through urban agriculture or water through rainwater collection and storage.  

For Masselot, both long-term and short-term solutions are necessary. “In the short term, it would be important for public health authorities to identify people at risk [of dying from a heatwave] so they can be notified in advance that high temperatures are looming and find ways of cooling down,” he says. “In the long term, cities will need more green spaces, less asphalt, but also to change their buildings so they store less heat, decrease pollution and ensure that they tend to populations with higher health risks,” Masselot explains.

To its credit, the city has acknowledged the vulnerability of its populace and is diligently working on implementing necessary measures. “Paris is far from being the black sheep when it comes to adapting for heatwaves,” says Masselot.

However, the urgency to act cannot be overstated. “Things are going to get worse and there will be longer heatwaves as time goes on,” he says. “Cities need to prepare for that as soon as possible.”