Urban green spaces are urgently needed across the Global South

Green spaces are becoming essential lifelines as global temperatures continue to rise. Increasing levels of heat are turning our cities into insufferable melting pots, where concrete and asphalt amplify the issue.

Rising heat is especially severe across cities of the Global South. Here, a lack of greenery compounded by rapid urbanization and inadequate infrastructure exacerbates already harsh living conditions.

A recent study has revealed that these cities have only about 70% of their “cooling capacity” compared to cities in the Global North, making them significantly more vulnerable to heat stress.

The rising threat of global warming in urban areas of the South is further intensified by the urban heat island effect, a phenomenon where dense construction and limited vegetation cause cities to be significantly warmer than their surrounding rural regions.

This worsens heat-related illnesses, disproportionately affecting low-income communities and creating a dire public health crisis for these vulnerable regions.

The power of green spaces

However, a cure for the relentless heat might not be as far-fetched as it seems. The introduction of urban green spaces is proven to be a highly effective approach to combat scorching temperatures.

The research team – including experts from the universities of Nanjing, Exeter, Aarhus, and North Carolina State – has found that there is “vast potential” to enhance urban cooling in the Global South and reduce inequality.

“Urban greenery is a really effective way of tackling what can be fatal effects of extreme heat and humidity,” said Professor Tim Lenton from the Global Systems Institute at the University of Exeter.

“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. Our analysis suggests green spaces can cool the surface temperature in the average city by about 3°C during warm seasons – a vital difference during extreme heat.”

The cooling effect of urban green spaces

The cooling effect of green spaces in cities, particularly urban forests, is attributed to shading and transpirational cooling, which is the evaporation of water.

The study utilized satellite data from the world’s 500 largest cities to gauge their cooling capacity – the extent to which urban green spaces could reduce a city’s surface temperatures.

The top ten cities with the highest cooling capacity were all located in the United States, with Charlotte and Raleigh-Durham in North Carolina topping the list.

Many US cities benefit from their low population density, despite this causing a side effect of “urban sprawl.” Low population density allows for larger green spaces and a significant cooling effect.

On the opposite end of the spectrum, cities like Mogadishu in Somalia, Sana’a in Yemen, and Rosario in Argentina were found to have the lowest cooling capacity.

Cooling benefits in the Global South

The Global South, which spans Africa, Latin America, and large parts of Asia, is where the risk of exposure to extreme heat is most severe.

A prior study warns that existing climate policies may leave over a fifth of the world’s population exposed to dangerously high temperatures by the year 2100 – with the most vulnerable sections located in India and Nigeria.

“The differences are mostly due to quantity of vegetation, but efficiency of cooling is also better in the Global North – possibly due to management of green spaces and different tree species,” said Professor Chi Xu of Nanjing University.

A greener future

Despite the disparities in cooling capacity and benefits, there is still a silver lining. “The good news is that this nature-based solution to cooling can be substantially improved across the Global South, helping to tackle future heat stress for billions of people,” said Professor Jens-Christian Svenning.

According to Professor Rob Dunn of NC State, creating a greener urban environment is not an easy task, but it’s a critical step toward making cities habitable in the near future.

“It won’t be easy to regreen cities. It can be expensive in the short-term. Yet, it will be key to making cities liveable in the immediate future. Also key will be working to prevent the loss of green space in those cities that have it, or at least that have a little,” said Professor Dunn.

“Changes could include ground-level green spaces and vertical and rooftop gardens, or even forests, to help protect city people from extreme heat.”

The study is published in the journal Nature Communications.

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