Yes, but preventing the melting of the Arctic ice cap requires that U-turn happening sometime around 2000 or earlier, and I don't see that happening. I expect the intertia already in the system is going to see substantial release of methane from former permafrost in the decade ahead, and even if we make substantial progress in a very short period of time, it'll be 20 years for that impact of that methane spike to fade.

This is like turning a super-tanker ... the lag between a hard turn on the rudder and the actual turn of the vessel is quite long. Add in that we were previously pushing the rudder hard the other way, and there is already momentum to the turn in the opposite direction.

What we would be aiming at in a hard, sudden change in policy is the limitation of the biosphere impact of the current Great Extinction event, hopefully avoiding a number of substantial biosphere system collapses, and retaining a prospect of complex industrial society surviving the century ahead. Both of those are laudable goals. But the time to make the turn and substantially mitigate all extreme climate change impacts was the 80's and the 90's.

I've been accused of being a Marxist, yet while Harpo's my favourite, it's Groucho I'm always quoting. Odd, that.