Global South cities have only 70% of cooling capacity as North ones: Study

Cities in the Global South are equipped with only about 70 per cent of the "cooling capacity" provided by urban greenery in cities in the Global North and are, therefore, are more vulnerable to extreme heat, a new research has found.

As the planet warms, researchers said that rising temperatures, along with 'urban heat island' effects, make cities hotter than rural areas. As a result, heat-related illness and deaths in these areas are becoming more common.

An international team, including researchers from the University of Exeter, UK, analysed satellite data on 500 of the world's largest cities to assess 'cooling capacity' -- how much do the urban green spaces cool down a city's surface temperatures?

"Our analysis suggests green spaces can cool the surface temperature in the average city by about 3 degrees Celsius during warm seasons -- a vital difference during extreme heat," author Timothy M. Lenton, from the University of Exeter, said.

"However, a concerning disparity is evident; on average Global South cities have only two-thirds the cooling capacity and cooling benefit compared to Global North cities," the authors wrote in the study published in the journal Nature Communications.

The disparity stems from differences in both quantity and quality of urban green infrastructure among cities, they said.

The researchers said that tropical and sub-tropical cities, which are located closer to the equator, tend to have relatively weaker cooling capacities.

"As Global South countries are predominantly located at low latitudes, this pattern leads to a situation in which Global South cities, which tend to be hotter and relatively lower-income, have, on average, approximately two-thirds the cooling capacity of the Global North cities," the authors wrote.

Therefore, they said that the cities that most need to rely on green infrastructure are, at present, those that are least able to do so.

Urban green spaces bring a cooling effect by providing shade and causing evaporation of water, the authors explained.

Over 50 Indian cities too were analysed, including Delhi, Pune and Chennai. Previous studies have estimated current climate policies to leave more than a fifth of humanity exposed to dangerously hot temperatures by 2100, with the largest at-risk populations in India and Nigeria, the researchers said.

"Currently, the people dying due to climate change are often in the slums of cities in the Global South, such as the hottest parts of India," Lenton said.

The researchers also found that there is "vast potential" to enhance urban cooling in the Global South and reduce inequality.

Mogadishu, a Somalian city, was found to have the lowest cooling capacity, followed by Sana'a in Yemen and Rosario in Argentina.