Why Joburg is Africa's top polluter
It's far easier to cut emissions at a local than at a national level, survey's leader says
Johannesburg has made it to number 13 in a list of leading cities, but not in a good way.
The city is 13th on a list of the world’s top 500 polluting cities. Other South African cities on the list — the first of its kind — are Cape Town (89th), Durban (102nd) and Port Elizabeth (335th).
Bloemfontein also gets a mention: It is 467th on the list when it comes to carbon footprint per capita. Johannesburg is 432nd on this list, but no other South African cities feature.
Joburg has the highest carbon footprint of any African city, according to researchers from the Norwegian University of Science and Technology who published their work in the journal Environmental Research Letters.
It is responsible for 28.9% of South Africa’s carbon footprint, and Cape Town is responsible for 7.4%.The only global cities with a worse pollution problem than Joburg are:1. Seoul, South Korea
2. Guangzhou, China
3. New York, US
4. Hong Kong, China
5. Los Angeles, US
6. Shanghai, China
8. Chicago, US
9. Tokyo/Yokohama, Japan
10. Riyadh, Saudi Arabia
11. Dubai, United Arab Emirates
12. Wuxi, China
And the only other African city in the top 500 is Banha, an important transport hub between Cairo and Alexandria. It is 17th on the list and responsible for 42.4% of Egypt's carbon footprint.
The researchers have created a website, citycarbonfootprints.info, which portrays the carbon footprint of every 250m x 250m area of land in the world.
The paper’s lead author, Daniel Moran, says he was surprised at just how concentrated carbon footprints are.
“The top 100 highest-footprint cities worldwide drive roughly 20% of the global carbon footprint,” he said. “This means concerted action by a small number of local mayors and governments can significantly reduce national total carbon footprints.”Moran said only about a third of the average individual’s carbon footprint is under their control. Most of our footprint was determined by buildings, commuting and energy use — issues directly under the influence of local governments.
Urban areas are home to about 54% of the global population and account for more than 70% of energy use, the researchers say. They are also centres for concentrated economic growth: one estimate suggests that 60% of global GDP is generated by just 600 urban centres.
Moran’s team began with the knowledge that economists have touted this concentration of buying power as an opportunity to develop economic growth strategies focused on a few local governments.
If emissions footprints were similarly highly concentrated, they correctly hypothesised, then a relatively small number of local governments could have a disproportionate effect on reducing emissions.
One of the key drivers behind the model they developed is the widely accepted paradigm that income is a strong predictor of carbon footprint. The more disposable income you have, the more likely you are to buy goods, travel overseas or drive an expensive, fancy car.
Moran and his team used income as a proxy for carbon footprint intensity, then matched it with data from other published research to calculate and refine carbon footprint numbers at the national and subnational level.
They also used national statistics on urban versus rural spending patterns, regional purchasing power data from a private market intelligence firm, and a population map.
The result is a global model that predicts the purchasing power, population and purchasing patterns for every grid cell worldwide.
To identify cities, they used a European Union model that identifies urban areas as contiguous densely populated areas, which may mean “Johannesburg” also includes Ekurhuleni and Tshwane.
While many of the urban areas with the highest carbon footprints are in countries with high footprints, 41 of the top 200 are in countries where total and per capita emissions are low.Here, Moran says, population and affluence in the urban areas combine to drive footprints at a similar scale to counterparts in the highest-income countries.
The researchers were also able to see the effect of wealthy enclaves, particularly in the US and in China, Moran said.
However, many of the cities with the highest footprints are also the richest, and thus have plenty of power to do something about it, Moran said.
“The fact that carbon footprints are highly concentrated in affluent cities means that targeted measures in a few places and by selected coalitions can have a large effect covering important consumption hotspots,” he said.
Mayors and citizens may also be willing to take more radical steps, such as switching the whole city over to green electricity, restricting private cars in the city centre or aggressively rewarding vehicle electrification.
Compared to countries, cities and local governments are often more nimble and can target the most effective solutions in different districts and demographic segments, Moran said.