IN 2019, IT IS IMPOSSIBLE to think about economic growth without confronting its most immediate implication.

We already know that over the next hundred years the earth will become warmer; the question is by just how much. The costs of climate change would be quite different if the planet got warmer by 1.5°C, or 2°C, or more.

The overwhelming scientific consensus is that human activity is responsible for climate change, and the only way to stay on a course to avoid catastrophe is to reduce carbon emissions.² Under the 2015 Paris Agreement, nations set a target to limit warming to a limit of 2°C, with a more ambitious target of 1.5°C. Based on the scientific evidence, the IPCC report concludes that in order to limit warming to 2°C, CO2 equivalent (CO2e) emissions³ would need to be reduced by 25 percent by 2030 (compared to the 2010 level) and go to zero by 2070. To reach 1.5°C, CO2e emissions would need to go down by 45 percent by 2030 and to zero by 2050.

Climate change is massively inequitable. The lion’s share of CO2e emissions are being generated either in rich countries or to produce what people consume in rich countries. But the greatest share of the cost is, and will be, experienced in poor countries. Does it make it an intractable problem, given that those who must solve it have no strong impetus to do so? Or is there some hope?