Cities located in the Global South are increasingly vulnerable to extreme heat due to the absence of cooling green areas, according to a recent study.
Recent research reveals that cities in the Global South are particularly susceptible to extreme heat because they lack cooling green spaces.
The investigation found that cities in the Global South offer only 70% of the “cooling capacity” that their counterparts in the Global North provide through urban greenery.
As temperatures rise and urban areas experience “urban heat island” effects—where cities become hotter than surrounding rural areas—there is an increase in heat-related illnesses and fatalities.
Implementing urban green spaces can mitigate this risk by lowering outdoor temperatures and creating essential safe havens.
This research, conducted by a global team from universities such as Nanjing, Exeter, Aarhus, and North Carolina State, suggests there is a significant opportunity to improve urban cooling in the Global South while addressing inequality.
Professor Tim Lenton from the Global Systems Institute at the University of Exeter stated, “Urban greenery is a powerful tool for combating the potentially deadly impacts of severe heat and humidity.”
“Currently, many deaths linked to climate change occur in the slums of Global South cities, particularly in the hottest regions of India.
“Our research indicates that green spaces can lower surface temperatures in an average city by around 3°C during warm seasons—an essential difference during heatwaves.”
The cooling benefits of urban green environments, especially forests, result from shade provision and the process of transpirational cooling, where water evaporates.
This recent study utilized satellite data from the world’s 500 largest cities to evaluate their “cooling capacity,” which measures how effectively urban greenery can cool city surfaces.
The cities that rank highest for cooling capacity are all in the USA, with Charlotte and Raleigh-Durham leading, followed by Kansas City and Baltimore. Many US cities have lower population densities, leading to urban “sprawl,” which allows for more green spaces and consequently enhances cooling.
Mogadishu in Somalia has the least cooling capacity, followed by Sana’a in Yemen and Rosario in Argentina. Notably, Chicago is the fourth lowest, being the only American city with a cooling capacity below 1°C.
‘Cooling benefit’
The Global South, which encompasses regions in Africa, Latin America, and much of Asia, includes areas most vulnerable to extreme heat.
An earlier study indicated that without significant climate policy changes, over a fifth of the world’s population could be exposed to dangerously high temperatures by 2100, especially in countries like India and Nigeria.
This latest research analyzed population density and geographic location to assess the “cooling benefit” for average citizens—since green spaces are most often located in wealthier neighborhoods.
Professor Chi Xu from Nanjing University noted that while cities in the Global South are behind regarding cooling capacity, the average resident experiences a cooling benefit of only 2.2°C, compared to 3.4°C for those living in the Global North.
He explained, “These gaps stem primarily from the amount of vegetation present, but the cooling efficiency tends to be more effective in the Global North, likely due to better management of green areas and different species of trees.”
Professor Jens-Christian Svenning from Aarhus University’s Center for Ecological Dynamics in a Novel Biosphere (ECONOVO) remarked, “The positive aspect is that this nature-based approach to cooling can be significantly enhanced across the Global South, addressing future heat challenges for millions.”
Professor Rob Dunn from North Carolina State University commented, “Reintroducing greenery into urban areas won’t be straightforward and could incur initial costs; however, it is crucial for ensuring cities remain habitable in the near term. It’s also important to safeguard existing green areas, however minimal they may be.”
Suggested improvements could involve creating ground-level green spaces, vertical and rooftop gardens, or even forests to shield urban residents from extreme heat.
