Articles - 2015: The growing challenge of heat in Europe's cities

 

Unlike floods or storms, extreme heat leaves little visible damage behind. There are no collapsed bridges or destroyed buildings to assess, and few physical loss indicators that align with the way catastrophe risk has traditionally been measured. This has made heat far harder to represent within conventional approaches to risk modelling, despite it being Europe’s deadliest weather-related hazard. The heatwave highlighted how rising temperatures, dense development and growing populations were pushing cities to the centre of Europe's future climate risk, requiring new approaches to designing and financing urban resilience.

 

The years since 2015 have only reinforced the trend. Europe has repeatedly experienced record-breaking heat, including the UK's first recorded temperature above 40°C in 2022, an estimated 67,873 heat-related deaths across Europe that same year, and a further estimated 50,798 deaths in 2023. This summer, another omega block again settled over Europe, bringing record June temperatures to both France and the UK.

 

Recent years have also seen increasing attention given to nature-based solutions as a practical way of reducing urban temperatures. International agreements such as the Sendai Framework for Disaster Risk Reduction and the Paris Agreement gave greater prominence to ecosystem-based adaptation, while European programmes including GrowGreen and Connecting Nature demonstrated how trees, parks, green roofs and other green infrastructure could provide measurable cooling benefits.

 

Today, urban cooling is becoming an increasingly common feature of resilience planning. The UK's Climate Change Committee has recommended introducing a statutory duty requiring local authorities to address overheating risks, from cooling public buildings to incorporating heat resilience into new developments. The question for insurers, property owners and city authorities is no longer whether to build for heat, but how. A recent WRN analysis, City heat -

 

The reason is straightforward: green infrastructure reduces temperatures before an extreme event occurs. Trees provide shade, vegetation cools the surrounding air through evapotranspiration and green roofs reduce heat absorbed by buildings. Reviews have shown neighbourhood-scale cooling from a range of nature-based solutions, while UK studies have found green façades can reduce neighbourhood temperatures by as much as 5.0°C.

 

Cooler cities carry benefits that extend well beyond temperature reduction alone. They ease pressure on healthcare systems, cut energy demand, boost workforce productivity and protect infrastructure during prolonged heatwaves. The healthcare impact alone is significant, with NHS England estimating that heat-related mortality already costs around £6.8 billion annually, rising to £14.7 billion per year by the 2050s. As a result, urban greening is increasingly becoming part of conversations around resilience, asset management and long-term risk.

 

Through its participation in the EU-funded NATURANCE programme, the Willis Research Network explored how innovative financing could complement physical adaptation. Rather than replacing existing emergency planning, the programme examined how predefined heat thresholds could automatically release funding when dangerous conditions developed. This would allow support to reach people faster, instead of waiting on funding decisions once a heatwave is already underway. 

 

A worked example for Central East London showed how a parametric structure, using wet-bulb temperature data tiered to the UK's five-level heat-health alert system, could plug into the city's existing emergency protocol individuals experiencing homelessness. The protocol already had funding; what it lacked was a mechanism to release it when needed most. Trigger-based financing applied to existing funds, rather than insurance as a standalone product, emerged as the more viable path forward.

 

Through its participation in the EU-funded NATURANCE programme, the Willis Research Network explored how innovative financing could complement physical adaptation. Building resilience to heat therefore requires both approaches. Designing cooler cities reduces the risk before an event develops, while financing mechanisms improve the ability to respond when thresholds are exceeded.

 

More broadly, the experiences of European cities during the summer of 2026 demonstrate that heat is increasingly acting as a multiplier of risk. Across Europe, prolonged periods of extreme temperature have contributed to health impacts, strained infrastructure and created conditions for significant wildfires, demonstrating how a single hazard can cascade across interconnected systems. As Europe continues to warm faster than any other continent, the resilience of its cities will increasingly be defined not only by their ability to withstand extreme heat, but by their capacity to anticipate, manage and adapt to the wider risks it creates.