With over two-thirds of the world’s population expected to live in cities by 2050, new data from the World Resources Institute (WRI) reveals the stark challenges urban areas will face due to climate change. The analysis, focused on the 1,000 largest cities globally, highlights the growing threats from extreme heat, disease, and energy demand, with low-income regions particularly vulnerable.
Under a scenario of 3 degrees Celsius (5.4 degrees Fahrenheit) of warming above pre-industrial levels, cities could endure significantly longer and more frequent heat waves compared to 1.5 degrees Celsius (2.7 degrees Fahrenheit) of warming. This would trigger skyrocketing demand for cooling and heighten risks from diseases such as dengue and Zika. The report underscores the urgent need for climate adaptation investments to protect urban populations.
“The difference between 1.5 degrees and 3 degrees has life or death consequences for billions of people,” said Rogier van den Berg, Global Director at WRI Ross Center for Sustainable Cities. “This data should serve as a wakeup call to city and national leaders to start preparing for a much hotter world while slashing emissions.”
Heat Waves, Energy Demand, and Disease Risks on the Rise
WRI’s analysis, supported by Bloomberg Philanthropies, examined climate hazards across 996 cities, home to 2.1 billion people (26% of the global population). The data reveals that at 3 degrees Celsius, most cities could face more intense and prolonged heat waves, with the longest heat waves lasting up to 24.5 days, compared to 16.3 days at 1.5 degrees. The number of cities experiencing heat waves lasting a month or longer could increase fivefold, affecting 302 million people.
In addition, cooling demand is projected to soar. At 3 degrees Celsius, 194 million people in urban areas could experience a 100% increase in cooling needs, putting immense strain on energy infrastructure, especially in low-income cities.
Warmer temperatures will also foster conditions for mosquito-borne diseases like dengue and Zika. In Brazil, for instance, 11 major cities could face high arbovirus transmission risk for six months of the year under 3 degrees Celsius warming.
Disproportionate Impacts on Low-Income Regions
Sub-Saharan Africa, Latin America, and Southeast Asia are among the regions that could be hardest hit. Sub-Saharan cities may experience a 56% increase in heat wave frequency and 25 more peak arbovirus transmission days annually. Similarly, Latin American cities could see a significant rise in heat wave frequency and disease transmission risks. In Indonesia, cities like Yogyakarta and Jember could experience a dramatic increase in the number of peak arbovirus days.
“Climate change has profoundly unequal impacts across and within cities,” said Anjali Mahendra, Director of Global Research at WRI Ross Center. “Low-income cities often have fewer resources to cope, making it critical to increase financing for adaptation and direct it to the hardest-hit areas.”
As cities are expected to grow by another 2.5 billion people by 2050, largely in lower-income regions, the need for swift climate action becomes even more pressing. National and local governments must collaborate to increase funding for adaptation, accelerate emissions reductions, and use data-driven approaches to prioritize high-risk areas.
“This research makes it clear that we can’t afford to delay action on climate change,” said Antha Williams, head of Bloomberg Philanthropies’ Environment program. “National and local governments must work together to protect millions of urban lives from the worst impacts of climate change.”
The findings were released in conjunction with the COP28 Local Climate Action Summit, which underscored the pivotal role that cities play in climate action and called for stronger multi-level partnerships to enhance climate adaptation and resilience efforts.