This summer, Europe is discovering what climate change feels like after dark. Across southern and central cities, so-called “tropical nights” — when temperatures fail to dip below 20°C — have surged. Once confined to the Mediterranean coast, they now stretch into Paris, Vienna, and Warsaw. Scientists warn that the danger is not just discomfort but physiological stress that pushes vulnerable bodies past their limits.
For Madeleine Thomson, Head of Impacts and Adaptation at Wellcome, the lesson is clear: heat is already a health crisis, and Europe’s health systems remain dangerously unprepared.
Heat That Lingers
April reporting by Sky News highlighted how the number of tropical nights in Europe has tripled in some regions since the 1960s, and is accelerating as global temperatures climb. Madeleine Thomson was blunt: “Europe is heating up, and we’re not prepared…extreme heat doesn’t just kill — it also increases the risk of heart disease, pregnancy complications, and poor mental health.”
Medical evidence backs her up. Sustained night-time heat prevents the body from cooling and recovering, making cardiovascular collapse, dehydration, and kidney stress more likely. For hospitals, the impact is immediate: spikes in admissions for heart failure and respiratory distress, often compounded by air pollution and wildfire smoke.
The Death Toll Mounts
This summer alone has been deadly. A rapid analysis by Imperial College London and the London School of Hygiene & Tropical Medicine found that 2,300 people died across 12 European cities during a ten-day late-June heatwave, with about 1,500 of those deaths directly linked to climate change that intensified the event.
The findings reinforce what climate epidemiologists have long argued: mortality figures understate the real toll. Heat often shows up as secondary causes — kidney failure, cardiac arrest, stroke — leaving many deaths “invisible” in official records.
Fire and Smoke
Heat has also fueled Europe’s most destructive wildfire season in years. By mid-August, around 400,000 hectares had burned, nearly double the long-term average. In Spain alone, flames scorched 158,000 hectares, forcing the deployment of 2,000 additional troops to support firefighting crews.
The fires have killed at least six people, including two firefighters, and forced tens of thousands to evacuate. But the health consequences extend beyond flames: smoke exacerbates asthma, chronic obstructive pulmonary disease, and cardiovascular illness, adding yet another burden on emergency rooms.
Counting the Economic Costs
Europe’s economies are also feeling the strain. Allianz Research estimates that the summer’s heatwaves could shave 0.5 percentage points off Europe’s GDP in 2025, with Spain’s output declining by as much as 1.4 points as labor productivity slumps on extreme-heat days.
For Thomson, the economic costs only reinforce the central point: heat is not just a climate issue. It is a health emergency with cascading consequences for communities, hospitals, and economies.
Thomson’s Trajectory
Thomson has spent over 25 years at the nexus of climate science and health. At Columbia University’s International Research Institute for Climate and Society, she directed the WHO Collaborating Centre on Malaria Early Warning Systems, pioneering methods that used rainfall and temperature forecasts to predict disease outbreaks. She also served as a Senior Research Scholar at Columbia’s Mailman School of Public Health, where her team explored how climate influences nutrition, hydrometeorological disasters, and infectious disease.
Now at Wellcome, she leads the foundation’s push to make climate and health a global priority. Wellcome’s strategy emphasizes funding interdisciplinary research, building networks that connect meteorologists with public-health officials, and translating science into policy and practice.
Integrated Surveillance: From Malaria to Heat
The thread running through her career is the call for integrated surveillance — merging climate data with health data so risks can be spotted early. At a 2024 World Meteorological Organization conference, she warned: “We can’t do climate and health without the climate. We need integrated surveillance and climate services for health and can no longer afford to be flying blind.”
That integration is starting to take shape through the WHO–WMO ClimaHealth portal, a knowledge-sharing platform Thomson helped champion, which brings together case studies, datasets, and policy tools for climate–health adaptation.
What Adaptation Could Look Like
In practice, a heat-ready health system would take several forms:
- Forecast-driven alerts. Night-time minima and heat indices would trigger hospital surge plans, ambulance staging, and outreach to at-risk patients.
- Cooling access. Cities would guarantee transit-accessible cooling centers, hydration stations, and shaded shelters, especially for vulnerable groups.
- Urban design. More tree canopy, water features, and reflective surfaces would reduce street-level temperatures in heat islands.
- Labor and education policies. Workplaces and schools would shift hours or move indoors during peak heat, with legal protections for outdoor workers.
- Smoke-health integration. Public-health messaging would combine heat and air-quality alerts, providing advice on masks, filtration, and exertion limits.
These are the measures Thomson has consistently advocated: practical, scalable interventions that save lives now and prevent the staggering mortality increases projected for the future.
Policy Gaps
The EU has begun to recognize the risk. In 2021, it adopted a new Climate Adaptation Strategy, emphasizing health resilience. Yet implementation varies widely, and funding remains limited. Cities like Paris and Barcelona have piloted cooling centers and greening projects, but few countries treat heat as a systemic health risk rather than a seasonal weather nuisance.
Thomson argues that must change. “Extreme heat isn’t just a summer inconvenience,” she told Sky News. “It’s a driver of long-term health burdens that will only grow if we fail to act.”
Conclusion
The mortality data from this summer — 2,300 deaths in just ten days — is a glimpse of what unchecked warming means for Europe. Add in record-breaking tropical nights, unprecedented fire seasons, and economic losses, and the conclusion is unavoidable.
For Madeleine Thomson, the choice is stark but simple: Europe can either integrate science, health, and policy to adapt, or it can resign itself to preventable deaths. The science demands preparation, not delay.
