City dwellers are bearing the brunt of extreme temperatures. Thanks to a phenomenon that makes urban areas hotter than their surroundings, cities such as Pretoria are as much as 6°C hotter than they could be.
Layered on top of the hottest months ever recorded, this means cities are killing their inhabitants.
The heat comes from decades of poor planning. Since the 1950s, the global focus of city infrastructure planning has been on cars, and on getting as many people as possible into tall buildings. In South Africa’s six big cities, this means tarmac crisscrossing what used to be fields and bushveld, big cement slabs providing parking for the cars they bring in, and high-rise apartment and office blocks sucking in their occupants. This both creates and traps heat, which leads to an urban heat island. This effect is worse at night, with cities storing heat – like an oven.
Consequently, during the summer of 2015-2016 temperature records have tumbled in these cities, with the midday heat going into the high 30s and low 40s.
The World Health Organisation (WHO) says urban heat islands, which both raise temperatures and trap pollutants, will have to disappear this century if future generations are to live healthy lives in cities. This need is particularly acute as half the world’s population now lives in urban environments.
The organisation says gases – particularly carbon monoxide, nitrogen oxides, volatile organic compounds and particulate matter (dust) – create a petrochemical smog that smothers cities. In India and China, urban heat islands have trapped so many pollutants that children have been kept out of school and entire industries have had to be shut down. In colder climates, heatwaves have combined with the pre-existing heat stress in cities to kill tens of thousands of people. The WHO estimates that air pollution and heat stress kill about four million people a year.
It says the combination of hot days and nights weakens the body to a level where it cannot recover.
Local figures for those affected are hard to find because little national research has been done, but Johannesburg is consistently ranked as one of the most polluted cities in the world, thanks to its heat island trapping dust from mining and many other pollutants. The WHO puts Pretoria in second place, followed by Cape Town and Durban.
The State of Green Infrastructure study into Gauteng’s urban planning, conducted by the Gauteng City-Region Observatory, found that historical development patterns had left its major metros – Tshwane, Ekurhuleni and Johannesburg – with serious problems.
“The region is facing worryingly high levels of dirty air, heat island effects, intense storms, polluted and even toxic water systems, shortages of land for food production, and a situation where people increasingly spend their lives in … artificially regulated building environments.”
The study does, however, acknowledge work being done in the region to undo this history of bad spatial development, with the cities envisaging a totally different version of themselves by mid-century.
According to research by Carolyn Hardy of the department of mechanical engineering science at the University of Johannesburg, it is only recently that urban planners have tried to turn this sort of urban planning in another direction.
The problem now is that budgets are small and any tweaking has to happen on top of existing infrastructure.
The current El Niño has exacerbated this problem, with record temperatures being set across South Africa. The phenomenon, which has seen the Pacific Ocean warmed by a record 3°C, leads to extreme heat and drought in the southern hemisphere.
Research by the City of Johannesburg for its 2040 strategy shows that, if not tackled, climate change will pile pressure on top of the existing urban heat island and see temperatures in summer push closer towards 50°C, rather than the high 30s that are now common.
Valerie Durant of the University of Pretoria says the solution is a comprehensive shift in the way cities are organised. The key step will be in greening cities, with an emphasis on public transport, meaning roads and parking lots can rather be used as urban forests and gardens. “We need to implement sustainable intensive urban agriculture.”
This could happen relatively easily, with roofs converted for gardening and encouraging vertical gardens to proliferate. Borrowing from cities elsewhere, motorways can be built under a layer of green infrastructure to create both more space for green space and reduce the heat effect of the tar.
Johannesburg, Cape Town and eThekwini have included this sort of thinking in their long-term strategies. Each city has begun a fundamental shift away from having one person in a car, with a large investment in rapid bus systems and cycling lanes. Johannesburg’s “corridors of freedom” will also try to use the shift in transport to change the spatial dynamic of the city, mixing low-cost and high-cost housing projects with business districts so people do not have to travel as much.
Large green areas will also be wrapped around the city, with public parks and sports areas encouraging people to spend less time in air-conditioned offices and homes.
This will add to the city’s 10-million trees and will also create space for urban gardens so fresh produce does not have to come in from the countryside. These measures are part of a wider initiative at local government level to make cities climate proof, so they are ready for when things get worse.
The Council for Scientific and Industrial Research predicts that the interior of the country will warm by up to 6°C this century, with the coast warming at half that rate. For cities that do not tackle their historically poor development, that will mean summers could become so severe that people will be unable to function in them.
Fortunately for South Africans, the metros are aware of this danger and are already changing their landscape.
Motor City takes a new direction
Detroit in the United States used to be the pulsing heart of the automobile revolution. The city built massive highways to bring people in to its car factories, and skyscrapers to house the companies that employed them.
Research by its municipal authority in the 1990s showed that this had created a heat island that pushed temperatures up by about 8°C. The 2009 economic collapse changed this, as the city’s car manufacturers closed shop overnight. Detroit is now a test case for rebuilding a city to be ecologically friendly.
Abandoned suburbs have been turned into urban farms that produce food, which is then bartered for other services. A new society is being built, with its lessons being replicated on a smaller scale in other cities around the US.
Urban planning courses at universities are using this as a case study, to show how resilient cities can be built on top of existing ones.
Researchers at the University of Michigan have found that this change has had a profound influence on the city’s heat island, with temperatures and pollution levels dropping significantly. Subsequent projects have started to examine the impact on people’s health. – Sipho Kings
Hubs of pollution act
The emission of greenhouse gases caused by humans means the world is getting hotter at a rate hitherto unseen in history.
The United Nation’s climate change body says this will lead to “irreversible change” this century if emissions are not lowered.
The world is already, on average, nearly 1°C hotter than it was before the industrial revolution kicked off. Southern Africa has warmed at double this rate. After a record-setting 2014 and 2015, the UK meteorological office is warning that 2016 is likely be the hottest year ever recorded.
The key is to lower carbon emissions, and cities, with their increasing population and financial muscle, are a key part of this. The C40 cities initiative has pulled together the world’s largest cities to act unilaterally to reduce carbon emissions.
This group signalled its ambition by holding a conference on the periphery of the COP21 climate conference in Paris late last year. South African cities are key partners of this initiative, and Johannesburg recently hosted the C40 annual conference.
South Africa as a whole has pledged to lower its greenhouse gas emissions by 42% by 2025. – Sipho Kings