I wonder what this city would be like if you stripped away the forest. I wonder to what extent the world's largest man made forest actually slurps up a lot of soot and carbon in the air (mostly from car but also factory smoke), and turns it into timber and roots. I imagine that each and every day when the forest sighs, huge amounts of fresh air are pumped into the streets of Johannesburg, and without these sighs of relief, Johannesburg would feel oppressive, even prison-like. Instead, if you actually live here, you find it is leafy and pleasant.
One of the concerns climate scientists often express is the 'tipping point' effect of warming, where the planet's lungs - the Amazon - begins to decline as warming breaches a maximum temperature threshold for forest making. If you actually travel to South America, you'll find vast areas around the Amazon that are sort've bushy and grassy, and you'd wonder: "How come there's dense forest right there, and not here?" The answer is that subtle variations are enough to persuade forests not to try. And the concern is that the warming trend may be enough to impact on large swathes of the Amazon - turning it into a carbon emitter.
I'm guessing that Johannesburg is fairly unique in that it is so high above sea level, meaning it will always have a milder climate. So far it seems climate change is going mean wetter weather in Rosebank and greater Gauteng. And if we take this summer - and one swallow doesn't make a summer - but potentially we can look forward to cooler summers.
This might be good news for the big lungs of Johannesburg, and the people who call Johannesburg home.