Hot in the city: Europe’s forecast excess death toll should ring alarm bells

There is a danger that the drumbeat of doom-laden warnings from climate and meteorological thinktanks simply numb readers into shoulder-shrugging acceptance of the catastrophe around the corner. But some are so stark that they should have the opposite effect — a jolt back to wide-awake reality and into action.

One of those emerged this week in the academic journal Nature Medicine, which warned that rising temperatures due to climate change could lead to 2.3 million extra deaths across 854 European cities by 2099, a 50 per cent increase in the death burden between 2015 and the end of the century.

Last year 2024 saw unprecedented global temperatures, following on from the remarkable warmth of 2023, according to Copernicus, the EU’s earth observation unit. It also became the first year with an average temperature clearly exceeding 1.5°C above the pre-industrial level — a threshold set by the Paris Agreement to significantly reduce the risks and impacts of climate change.

Coming soon after wildfires that ripped through California displacing 150,000 people and causing an estimated $250 billion of damage, these heat warnings seem more pertinent than ever. The excess deaths in the new research are not as dramatic but are driven by important factors that impact cities when temperatures rise over the longer term.

Another study last year into more than 850 European cities with populations of more than 50,000 — and which found London and Paris as recording the most heat-related deaths over the 20 years to end of 2019 — identified urban heat islands (UHI) as a contributory cause.

This effect occurs when artificial dark materials like bitumen in roads and buildings trap heat throughout the day and emit it after sunset, preventing nighttime cooling. City dwellers face warmer temperatures compared to those living in rural regions, which is how this effect got its name. The removal of vegetation during urban development eliminates natural cooling elements that could help counteract these elevated temperatures.

Research by engineering consultancy Arup based on climate models from the University of Reading found that the UHI effect was pushing up temperatures in cities like London, Madrid, Mumbai, and Los Angeles. Many cities are intensifying the problem, with the most vulnerable often the worst impacted with poorer neighbourhoods more likely to experience higher temperatures.

Night crawler

Urban heat is particularly significant in cities at night because building materials such as cement store heat during daylight hours and emit it after sunset. This thermal retention creates health challenges and especially affects sensitive populations such as young children and older adults.

Most urban areas showed stark temperature differences, according to Arup. The warmest locations had minimal greenery (less than 6 per cent plant coverage), while the coolest areas — found primarily in parklands separate from housing and business districts ­ — were heavily vegetated (exceeding 70 per cent coverage). This vegetation disparity led to significant temperature variations across these cities.

Photo by Igor Karimov 🇺🇦 on Unsplash

It is also worth noting that the Nature Magazine research found that the problems will be worse in the poorer, more southern parts of Europe. There was a strong Mediterranean effect, with the highest net effects in eastern Spain, southern France, Italy and Malta, which corresponds to a region in which the rate of climate warming is faster than elsewhere. A central Europe hotspot is also apparent, covering Poland and southern Germany as well as Switzerland and Austria.

The next question is what can be done. The World Bank, which runs the Global Platform for Sustainable Cities, is concerned about the threat of extreme heat in urban settings and particularly its adverse impacts on health. In a keynote report last October it said it could see the benefit of shifting towards a focus on targeted interventions and boosting preparedness away from just looking at integrated measures such as urban cooling.

Future investments might include a standalone heat-focused project that would state an explicit link between investment activities and urban heat. The Bank is aware it can make more effort to address urban heat with its own investments, such as by identifying their impacts on urban heat within the local context and focusing more on protecting vulnerable groups from heat-related risks. Given the size of its investment portfolio, this is significant.

But city leaders need to be thinking about they can do on a smaller scale. There is a growing consensus around the need for nature-based solutions that help mitigate the heat effects without involving major new construction. Introducing street trees, urban parks, green roofs, and wetlands can all lower urban temperatures.

The C40 Cities think tank and campaign group has asked members to sign up to a pledge to allocate 30 per cent to 40 per cent of their total built-up city surface area to green spaces or to permeable spaces such as water-absorbent pavements, infiltration trenches, and swales (or rain contours) that capture rainwater directly where it lands. It may take time to deliver results, but each initiative will help reduce the drumbeat of doomy news.