Johannesburg has become the fastest location in the country to register property and get an electricity connection, followed by Cape Town and eThekwini (Bloomberg)
Cities have always been hotter than the countryside. Concrete and tar soak up and exacerbate heat. Trees, which do the opposite thing, are replaced by tall buildings which instead reflect and trap heat. That creates what is known as an urban heat island. This is a bubble of hot air that sits over all our cities, making them stiflingly hot when compared to the countryside around them.
For the capital city, Pretoria, this effect means people living in the CBD have to contend with temperatures that are already some 6°C hotter than they would be if the city wasn’t there. Durban, Johannesburg, Cape Town and the metros all have a similar problem.
The World Health Organisation said in research last year that these heat islands trap carbon monoxide, nitrogen oxides, dust and volatile organic compounds in a petrochemical smog. Combine this with heat stress, and it kills four million people a year across the globe. Heat stress is when the air is so hot that sweating no longer helps to cool people down, so they start to boil. This tends to overwhelm the young and old, leading to hospitalisation and death.
Its research said Johannesburg has the most polluted heat island, closely followed by Cape Town and Durban.
But until now, little research had been done into how global warming will dovetail with that heat island effect – to make things much worse. New research from the University of Sussex – “Heat island effect could double climate change cost for world’s cities” – has put a number to the warming, and to the economic cost.
Looking at more than a thousand of the world’s biggest cities, the research in Nature Climate Change said the worst-hit cities would be over 8°C hotter than they are now.
This would cost 10.9% of their gross domestic product each year, in things such as people dying from heat exhaustion and businesses losing productivity. More energy will be needed to cool buildings, which in turn will warm the cities more, while hospitals become overwhelmed by people needing to be treated for heat exhaustion.
The average impact for cities across the world will be in losing 5.6% of their gross domestic product. That will, in effect, mean that cities enter a spiral of becoming poorer and poorer.
That is if the world continues to release greenhouse gases at a rate near what it is doing now. And, while emissions have plateaued in the last year, events such as the United States leaving the Paris Agreement on tackling climate change mean emissions will continue without dropping significantly.
The researchers warned about events such as this: “Any hard-won victories over climate change on a global scale could be wiped out by the effects of uncontrolled urban heat islands.”
Half of the world’s population lives in cities, which consume 78% of the world’s energy and produce 80% of its gross domestic product.
Reducing carbon emissions and the impact of each city’s urban heat island is therefore critical for the future of humanity, according to the researchers.
Initiatives such as the C40 Cities Climate Leadership Group, which South Africa’s big metros are members of, have ambitious plans to reduce their own impact on warming the planet and ensure they lessen the impact of their urban heat islands and local warming.
The Sussex researchers give a nod to this city-based action, saying: “It is clear that we have until now underestimated the dramatic impact that local policies could make in reducing urban warming.”
Johannesburg has started initiatives such as its “corridors of freedom” to lower emissions and heat coming from people driving their own cars. These also mix housing with business districts so people don’t have to travel for work. On top of that, the city plans to add to its green forest of 10-million trees with more green spaces and sports areas so people get out and about, rather than spending time in air-conditioned offices.
The warnings are being sounded, while the solutions are there to be used. Mayors and governments just have to heed them and use the tools at hand.