Hanging over everything is the growing recognition that the United States isn’t going to play. Not this year, perhaps not in any year. If Congress couldn’t pass a climate bill so feeble that it consisted of little but loopholes while Barack Obama was president and the Democrats had a majority in both houses, where does hope lie for action in other circumstances? Last Tuesday the Guardian reported that of 48 Republican contenders for the Senate elections in November only one accepted that man-made climate change is taking place. Who was he? Mike Castle of Delaware. The following day he was defeated by the Tea Party candidate Christine O’Donnell, producing a full house of science deniers. The enlightenment? Fun while it lasted.

What all this means is that there is not a single effective instrument for containing man-made global warming anywhere on earth. The response to climate change, which was described by Lord Stern as “a result of the greatest market failure the world has seen”, is the greatest political failure the world has ever seen.