A new study ranks the 205 cities most threatened by rising temperatures (also considering population vulnerability)

A new study from the University of Oxford has ranked 205 of the world's largest cities according to their risk from extreme heat. Rising global temperatures are becoming a threat to health especially in urban contexts characterized by high population density and socioeconomic disparities. As the research states, in fact, the risk is not due to simple exposure to heat. The effects on people also depend on population vulnerability and the ability to cope with increasingly hotter cities.

Extreme heat in the city: looking beyond the temperatures

During the'heat wave Between late June and early July 2025, thousands of excess deaths occurred in Europe (2.305 in just 12 major cities). Projections suggest the numbers are set to rise sharply, driven by factors such as an aging population and intensifying climate risks.

According to the 2022 IPCC report, urban populations are exposed to a “disproportionately high risk“: in the city, in fact, anthropogenic warming, the soil cover, the population density and socioeconomic disparities exacerbate the effects of rising temperatures. Heat, in short, is not the same everywhere. In addition to exposure, a study just published in Sustainable Cities and Society, other risk components must be considered, especially those linked to adaptability to an increasingly warmer climate.

How do you explain Nethmi Jayaratne Kariyawasam of the Oxford Smith School of Enterprise and the Environment, lead author of the research,

"It's not just exposure to high temperatures that matters for risk. Our study highlights the importance of global heat-related risk assessments, which reveal the diverse mechanisms through which heat-related urban risk emerges. In many large cities, particularly in Asia and Africa, extreme heat coincides with high vulnerability and limited capacity to cope. This combination can substantially increase heat-related risk and, in some cases, have life-threatening consequences."

The world's most at-risk cities: the study's results

The study examined 205 cities with a population greater than one million and classified them based on a harmonized score that considers a series of key risk indicators beyond simple heat exposure. Among the factors considered are demographic and socioeconomic conditions that increase susceptibility to heat-related illnesses and mortality, such as age and economic resources, as well as access to cooling infrastructure such as air conditioning and ecological barriers such as tree cover.

India, Pakistan, Nigeria, and Ghana These countries are home to the largest number of cities with high risk scores: over 95% of the most at-risk cities are located in South and Southeast Asia and sub-Saharan Africa. Major tourist destinations and international business centers, including Cairo (Egypt), Bangkok (Thailand), Hanoi (Vietnam), and Jaipur (India), also appear among the top 50 cities.

The most at-risk city in the world, according to research, is Basra, IraqTo find the top city in the Northern Hemisphere, scroll down to 75th place in the ranking, where Phoenix, in the United States, is located. The European cities most at risk are Bucharest, Rome, Barcelona, ​​Milan, Paris, and Warsaw, followed by Madrid, Munich, and Berlin.

Air conditioning is not a sustainable solution

The results, the researchers explain, demonstrate that exposure alone is not sufficient to predict risk. Several highly exposed cities (for example, Kuala Lumpur, Bangkok and Jeddah) rank lower thanks to a strong ability to adapt – which includes increased vegetation cover and more affordable energy – while others (such as Karachi, Faisalabad in Pakistan, and Kaduna in Nigeria) face high risk despite showing moderate heat exposure.

La vulnerability to heat It also depends on the socioeconomic situation and infrastructural deficiencies. As the study states,

While air conditioning can reduce acute heat stress for those who have access to it, relying on it as the primary adaptation strategy is unsustainable, especially given its high costs and high energy consumption. Rising demand for fossil-fuel-generated electricity, the high content of global-warming refrigerant gases, and waste heat emissions can exacerbate urban warming over time.

As the doctor explained Radhika Khosla, associate professor at the Smith School of Enterprise and the Environment, who co-supervised the research,

Demand for air conditioning is rising worldwide, yet many cannot afford it. And if we overly rely on this energy-intensive form of cooling, we risk further exacerbating global warming, triggering a vicious cycle. To extend adaptation and thermal comfort to everyone, we must consider a multifaceted approach to ensuring people's safety, starting with solutions that include passive cooling and energy-efficient technologies like fans and air conditioners.

Here are three insights that might interest you:

Urban Microclimate: How Heat Shapes the Cities of the Future
Why trees alone won't stop urban heat
Green Medellín: The City That Beats the Heat with Nature