As the world continues to warm, urban areas are increasingly at the forefront of the climate crisis. A recent analysis by the World Resources Institute (WRI) reveals a stark contrast in climate impacts between a world that warms by 1.5°C and one that sees a 3°C rise, with cities facing some of the most severe consequences.
More than half of the world’s population currently resides in cities, and this figure is expected to rise to two-thirds by 2050, placing immense pressure on infrastructure and public health systems. Low-income cities, particularly in sub-Saharan Africa, Latin America, and Southeast Asia, are poised to bear the brunt of this crisis.
Heat waves: a growing threat
One of the most immediate threats is the increasing frequency and severity of heat waves. Under the current trajectory of 3°C warming, the world’s largest cities will experience both longer and more frequent heat waves. The WRI’s research, which examines climate data from 996 of the largest global cities, shows that at 1.5°C, the longest heat wave might last an average of 16.3 days annually. However, in a 3°C scenario, this figure leaps to 24.5 days, with more than 16% of cities – home to 302 million people – facing heat waves lasting a month or longer every year.
The number of heat waves is also projected to increase, further straining public health, labor capacity, and productivity. A 3°C world will see an average of 6.4 heat waves per year in cities, compared to 4.9 at 1.5°C. The rising heat will not only disrupt daily life but will also significantly elevate the demand for cooling, creating a cascading effect on energy infrastructure. According to the report, 194 million people could face a doubling in cooling demand at 3°C warming – a staggering increase from the 8.7 million affected at 1.5°C.
Public health risks from climate-driven disease spread
Higher temperatures also create optimal conditions for the spread of diseases like dengue, Zika, West Nile, and yellow fever, as mosquitoes that carry these viruses thrive in warmer environments. The WRI analysis suggests that under a 3°C warming scenario, cities could experience six additional peak transmission days for arbovirus-carrying mosquitoes annually.
The geographic distribution of this threat is far from uniform. For example, Brazil, which is already grappling with a dengue crisis, could see its largest cities face high arbovirus risks for at least six months each year at 3°C warming.
While the analysis indicates a reduction in malaria transmission days globally at higher temperatures, cities in temperate regions, including parts of Europe and North America, may experience an uptick in malaria risk.
This geographical shift adds further complexity to managing disease outbreaks, particularly for regions unaccustomed to dealing with these types of public health emergencies.
The disproportionate impact on low-income cities
The WRI findings highlight how climate change exacerbates existing inequalities, with low-income cities bearing the worst of the impacts. Sub-Saharan Africa, in particular, is projected to face the largest increases in heat wave frequency and arbovirus transmission days.
The region could see a 56% rise in heat waves, experiencing an average of 6.5 annually at 3°C warming, along with an additional 25 peak arbovirus transmission days, bringing the annual total to 129 days.
Latin American cities will also see a significant increase in heat wave frequency, with an estimated 48% rise. Southeast Asia is another region facing compounding risks, particularly in Indonesia, where cities like Yogyakarta and Padang could see peak arbovirus days increase by hundreds at 3°C warming.
“Climate change has profoundly unequal impacts both across cities and within cities,” said Anjali Mahendra, Director of Global Research at the WRI Ross Center. “Cities in low-income countries are often more afflicted and have fewer resources to cope, which means we need to drastically increase financing for adaptation and find ways to direct it to the hardest-hit cities and communities.”
Infrastructure strain and the need for investment
The escalating climate impacts on cities will also strain infrastructure systems, particularly energy and healthcare.
The massive rise in cooling demand highlights the urgent need for investment in resilient energy infrastructure. The WRI’s analysis makes it clear that cities must prepare for a future where energy access is not only about meeting growing demand but also ensuring that vulnerable populations can cope with extreme heat without exacerbating greenhouse gas emissions.
Furthermore, the increased risk of disease outbreaks in urban centers will challenge public health systems that are already stretched thin, particularly in low-income cities.
Investing in climate adaptation measures that strengthen public health infrastructure will be crucial to saving lives.
The WRI report emphasizes that national and local governments must collaborate more effectively to address the growing climate crisis in urban areas.
“The difference between 1.5 degrees C and 3 degrees C has life or death consequences for billions of people worldwide,” said Rogier van den Berg, Global Director of the WRI Ross Center for Sustainable Cities. “This data should serve as a wake-up call to every city and national government leader: now is the time to start preparing cities for a much hotter world, while doing everything we can to slash emissions.”
The report advocates for the use of city-specific climate data to inform investments and policies. This approach, supported by tools developed by WRI and backed by Bloomberg Philanthropies, could help cities better prepare for the unique challenges they face.
“Better data is the key to sound decision-making, especially during this era of accelerating climate impacts,” said Eric Mackres, Senior Manager, Data and Tools, at WRI Ross Center.
As the world edges closer to 3°C of warming, cities must be at the center of climate action. Without swift and decisive measures to reduce emissions and increase adaptation funding, billions of people – particularly in low-income cities – will face life-threatening health risks, infrastructure failures, and economic instability. This research underscores the need for immediate, data-driven action to protect urban populations from the worsening effects of climate change.
“This research makes it clear that we can’t afford to delay action on climate change any longer as dire consequences await cities in a 3 degrees C world,” said Antha Williams, who leads the Bloomberg Philanthropies’ Environment program. “Now it’s more important than ever for national and local governments to come together to accelerate progress and protect the millions of lives in urban communities from the threatening impacts of climate change.”
Dataset:
City-scale climate hazards at 1.5°C, 2.0°C, and 3.0°C of global warming (2024), World Resources Institute
Technical note:
Wong, T. and E. Mackres, City-Scale, City-Relevant Climate Hazard Indicators Under 1.5°C, 2.0°C, and 3.0°C of Global Warming (2024), World Resources Institute | DOI: 10.46830/writn.23.00154
Article Source:
Press Release/Material by World Resources Institute (WRI)
Featured image credit: lifeforstock | Freepik
