Cities in the Global South are facing increased exposure to extreme heat due to a lack of cooling green spaces, according to a new study. Researchers found that Global South cities have only 70% of the “cooling capacity” provided by urban greenery in the Global North. This is a significant concern as temperatures are on the rise, and the “urban heat island” effect further exacerbates the heat in cities compared to rural areas. This has led to a rise in heat-related illnesses and deaths, especially in the slums of cities in the Global South.
Urban green spaces play a critical role in reducing the risk of heat-related illnesses by cooling down outdoor environments and providing vital refuges. The research, led by an international team including universities such as Nanjing, Exeter, Aarhus, and North Carolina State, highlights the vast potential to enhance urban cooling in the Global South and reduce inequality. Professor Tim Lenton of the University of Exeter emphasized the effectiveness of urban greenery in tackling the fatal effects of extreme heat and humidity, particularly in the hottest parts of cities in the Global South where people are most at risk.
The study utilized satellite data on the world’s 500 largest cities to assess their “cooling capacity” through urban green spaces. The top cities with the highest cooling capacity were all in the USA, reflecting the benefits of green spaces and low population density in these areas. Conversely, cities with the lowest cooling capacity included Mogadishu in Somalia, Sana’a in Yemen, and Rosario in Argentina. The study also highlighted the importance of green spaces’ cooling effects, especially urban forests, which are attributed to shading and transpirational cooling.
The Global South, comprising regions in Africa, Latin America, and much of Asia, faces the highest risk from extreme heat, with India and Nigeria having the largest at-risk populations. The study estimated the “cooling benefit” received by the average citizen in Global South cities to be lower compared to those in the Global North, mainly due to differences in the quantity of vegetation and the efficiency of cooling. Professor Chi Xu of Nanjing University noted that while the Global South cities lag behind in cooling capacity, there is potential for improvement to address future heat stress for billions of individuals.
Professor Jens-Christian Svenning from Aarhus University highlighted the positive impact of nature-based solutions in improving urban cooling across the Global South. However, he also acknowledged the challenges and costs associated with regreening cities in the short term. Professor Rob Dunn of North Carolina State University emphasized the importance of preserving existing green spaces in cities and implementing innovative solutions such as ground-level green spaces, vertical gardens, rooftop gardens, and urban forests. These efforts will be essential in creating livable cities and protecting populations from the increasing threat of extreme heat in the coming years.