Hope from Paris

DID the Paris climate accord save civilisation? Maybe. That may not sound like a ringing endorsement, but it's actually the best climate news we've had in a very long time. This agreement could still follow the path of the 1997 Kyoto Protocol, which seemed like a big deal but ended up being completely ineffectual. But there have been important changes in the world since then, which may finally have created the preconditions for action on global warming before it's too late.

Until very recently there were two huge roadblocks in the way of any kind of global deal on climate: China's soaring consumption of coal, and the implacable opposition of America's Republican Party. The first seemed to mean that global greenhouse emissions would rise inexorably no matter what wealthy countries did, while the second meant that the biggest of those wealthy countries was unable to make credible promises, and hence unable to lead.

But there have been important changes on both fronts.