As the world waits on the US, a sense of déjà vu in Denmark?

Sums like that are not on offer. The Europeans have talked about a deal in the range of $100 billion a year, but that depends on the Americans ponying up, and so far the US has been as coy about its willingness to pay as about its willingness to rein in emissions. Everyone outside the US knows that this is - overwhelmingly - a problem we’ve caused; since the carbon molecule has a residence time of over a century in the atmosphere, it will be the decades before the Chinese, despite their vastly larger numbers, are as responsible for climate change as Americans. But if Obama puts a realistic number on the table, Senator James Inhofe (R-Armageddon) will be on hand to take it off. (Inhofe originally announced he was going to Denmark as a “one-man truth squad,” but then added John Barasso (R-WY) and “a secret person” to his delegation). In our poisonous politics, the idea of the US meeting anything like its moral obligation seems small - and without that, the politics gets harder for everyone else in the world.

Against this backdrop, there’s a lot of important and less flashy stuff that has to move forwards if we’re ever going to reach an agreement. Nations with large swaths of forest, for instance, seem willing to make a deal to stop their destruction. It’s cheap compared with the other steps we’ll need to take, so it will probably happen - though the devil is deeply in the details. The same with credits for farmers for keeping carbon in the soil - it could be a big help, or a loophole large enough to drive an endless fleet of combines through.

And then there are the plumbing questions. How do you monitor and then enforce any agreement? How do you draw something up that doesn’t require treaty approval by the US Senate (no one thinks there are 67 votes for a real climate policy)? How do you give credit for actions already taken? How do you keep carbon trading from turning into one more Wall Street boondoggle?

One thing will surely be tested: whether civil society is capable of really pushing the process. Activists will be descending from all directions, but the deck is stacked against them. The conference centre, where the media will be mostly cooped up, is miles from town. And the environmentalists themselves are deeply split. There are groups that, for all intents and purposes, are part of the negotiations - whose experts have spent careers working on one part of the treaty or another, and are deeply invested in its success. There are less formal groups - many of them veterans of the anti-globalisation movement - determined to shut down the whole process. They won’t succeed, but it’s completely conceivable that tear gas will drift across the Radhuspladsen before the month is out. And there are thousands of young people, about to be disillusioned by their first exposure to big time power politics.

Having been to Kyoto (which at least took place in the daylight) there’s a sense of overwhelming déjà vu as I head towards Denmark. There, too, most of the world was lined up to do something, but waiting on a signal from the US, whose negotiators had been doing its best to weaken the treaty in hopes it might pass Senate muster. There was the same will-he-come anxiety, then centred on Al Gore, who flew in at the last minute to offer some small concessions and let the conference proceed. In those days China hadn’t yet emerged as a huge carbon source. In those days the Arctic hadn’t yet melted. But in those days, as in this one, everyone was waiting on the US