Ranking the world’s most vulnerable cities for heat risk – Oxford research
New research from the University of Oxford has analysed 205 global cities to determine where people are most at risk from rising global temperatures. The paper, published today in Sustainable Cities and Societies, looked at key indicators of risk across hazard exposure, vulnerability, and coping capacity.
India, Pakistan, Nigeria and Ghana host the largest number of cities with high risk scores, and more than 95% of the most at-risk cities are in South and Southeast Asia and Sub-Saharan Africa. Major tourist destinations and international business hubs, including Cairo (Egypt), Bangkok (Thailand), Hanoi (Vietnam) and Jaipur (India) are also ranked in the top 50. The analysis identifies the city of Al Basrah in Iraq as the world’s most at-risk.
“It isn’t just exposure to hot temperatures that matters for risk,” explains lead author Nethmi Jayaratne Kariyawasam, a DPhil researcher at the Oxford Smith School of Enterprise and the Environment. “Our study highlights the importance of multi-faceted global heat risk assessments, which reveal the diverse pathways through which urban heat risk emerges.
In many major cities, particularly across Asia and Africa, extreme heat coincides with high vulnerability and limited coping capacity. This combination can substantially increase heat risk and, in some cases, have life-threatening consequences.”
The study ranks 205 cities with a population of over 1 million, and defines a core set of risk indicators that allows for consistent cross-city comparison, rather than providing an exhaustive account of all factors that influence urban heat risk.
The factors considered include the demographic and socioeconomic conditions that increase susceptibility to heat-related illness and mortality, such as age and financial means, as well as access to cooling infrastructure such as air conditioning, and ecological buffers such as tree cover.
Radhika Khosla, Associate Professor at the University of Oxford, who co-supervised Nethmi’s research said, “Our study shows that heat risk planning needs to explicitly address not just exposure to high temperatures, but vulnerability and coping capacity.
Air conditioning demand is increasing worldwide, but many cannot afford it. And if we over-rely on this energy-intensive form of cooling, we risk further global warming in a vicious cycle. In order to scale adaptation and thermal comfort for all, we must consider a nuanced approach to keeping people safe, sequencing solutions with passive cooling and low-energy technologies such as fans and coolers being the first step.”
Jesus Lizana, Associate Professor at the University of Oxford and co-supervisor of the research, said: "This study provides the first globally harmonised and directly comparable assessment of urban heat risk across cities worldwide. This provides a powerful tool for identifying where adaptation efforts are most urgently needed and, in the future, as datasets continue to improve, future iterations of this framework could support the monitoring of climate adaptation progress and urban heat resilience at the global scale."
