It won't take decades, because we are not going to do anything. Well, there might be a bit of corruption. Politicians have relatives who can make big money on

It won't take decades, because we are not going to do anything. Well, there might be a bit of corruption. Politicians have relatives who can make big money on environmental projects. The financial industry is all excited about carbon trading, with high-frequency trading and insider trading and intentional crashes and lots more fun. Political "donations" have to be generated somehow, and the lingering possibility of legislation does that well no matter which side a politician has chosen. Crashing the economy to combat climate change seems like an abstract far-off concept until you lose your source of income. Most countries aren't about to crash their economies. The ones that do so will end up under new management after revolution or after being conquered in their weakened state.