The Stern review, published in 2006, pointed to a 75% chance that global temperatures would rise by between two and three degrees above the long-term average; he now believes we are “on track for something like four “. Had he known the way the situation would evolve, he says, “I think I would have been a bit more blunt. I would have been much more strong about the risks of a four- or five-degree rise.”

That would be 4° to 5°C aka 7° to 9°F aka the end of civilization as we know it (see World Bank Climate Report: ‘A 4°C [7°F] World Can, And Must, Be Avoided’ To Avert ‘Devastating’ Impacts).