Climate change is no longer a distant threat for Europe—it is a very real and immediate challenge that could reshape life across the continent for generations to come. A new major study published in Nature Medicine, led by the London School of Hygiene & Tropical Medicine, has delivered a sobering warning: without strong action, more than 2.3 million people in European cities could die by the end of this century due to rapidly rising temperatures. This editorial explores the science, the cities at risk, public health concerns, and the urgent need for action.

The Study’s Stark Findings

Researchers studied data from 854 cities in 30 European countries, looking at how temperature changes could affect peoples’ risk of dying. They found that the number of deaths tied to heat will rise steeply over the coming decades, and this increase will far outweigh any decline in deaths due to cold weather. In other words, the warming climate is expected to do much more harm than good when it comes to public health.

Southern and central Europe will be affected most. Mediterranean cities, in particular, will see the highest increases in deaths. For example, Barcelona could see over 246,000 deaths, Rome 147,738, and Athens nearly 88,000 by 2099 due to the impact of heat waves and high temperatures. These cities already face hot summers, and their older populations are more at risk when the heat gets extreme.

Not Just a Mediterranean Problem

Although southern Europe will be harder hit, the rest of the continent is not free from danger. For a short time, places in Northern Europe like Sweden, Finland, and Ireland may see fewer deaths because of warmer winters. However, these gains will not last. As extreme temperatures become more common, even cities like Helsinki and Stockholm could see new risks from heat, and the overall number of deaths across Europe will still rise sharply.

Why the Numbers Are So High

There are two key reasons for this dramatic increase in risk:

• Europe is warming faster than any other continent, with temperatures rising at twice the global average rate.

• Cities have lots of buildings and paved areas, which trap heat and create what scientists call "urban heat islands." Older people, children, and those with health problems are especially vulnerable.

The researchers stress that even optimistic adaptation plans will not be enough. Adding more trees, improving insulation, and using air conditioning will help, but without major cuts to carbon pollution, the projected death toll remains alarming.

Can Adaptation Help?

Efforts to adapt to rising temperatures—like planting more greenery in cities, building water features, and making homes more efficient—are important. These changes can cool cities and make life easier during heatwaves. But the new research shows that adaptation alone will not save enough lives, especially in the most at-risk areas like Italy, Spain, and Greece.

Only Drastic Emissions Cuts Will Work

The study makes a clear call: only deep, rapid reductions in greenhouse gas emissions can prevent this looming public health disaster. If carbon emissions are quickly lowered, up to 70% of the forecast deaths could be avoided. This means acting now to reduce dependence on oil, gas, and coal, and switching to renewable energy sources like wind and solar power.

Public Health Is at Stake

Climate change is not only about hotter weather and environmental impacts. It poses a direct threat to health on a massive scale. Extreme heat can cause heart attacks, strokes, miscarriages, and serious mental health issues. In June 2025 alone, over 2,300 people died in Europe due to extreme heat waves—an alarming sign of what may come if stronger actions are not taken