If there were any lingering doubts, they should now be dispelled. Gordon Brown will not be a green prime minister. As the Chancellor stood in parliament on 6 December and rattled off a few piecemeal environmental sops, environmentalists' hopes that he might actually have read and understood the Stern report were dashed on the rocks of reality. Climate change may be, in Sir Nicholas's words, "the greatest market failure the world has ever seen", but this is a failure that Brown seems determined to compound.
Brown's pre-Budget report wasn't all bad. The increase of air passenger duty from £5 to £10 is to be welcomed, particularly as it has made easyJet unhappy: a worthy aim in itself. But by only raising petrol prices in line with inflation, Brown has ensured that travelling by car will remain the default transport for almost everyone. Raising fuel taxes could have achieved the same objective as road pricing, with much less hassle and potential invasion of privacy. By refusing to make driving more expensive, the Chancellor wears his surrender to the motoring lobby as a bright green badge of failure.
If Stern is at all disappointed by Brown's timidity, he is keeping shtum for now - though if the Times is to be believed, Stern has already been "frozen out" of Brown's inner circle because of his forthright views on the urgency of tackling climate change. But Stern is not alone: the Environment Secretary, David Miliband, has been showing some very positive signs of "getting it" on climate - though it is worrying that not one of the more ambitious proposals outlined in Miliband's letter to Brown (leaked to the media back in October) actually made it into the Chancellor's statement.
I know it's probably too much to ask, but is there any chance that the Labour Party could skip the middleman and go straight on to Miliband for the next PM? The Environment Secretary's musings on carbon rationing were perhaps the single most significant piece of thinking to come out of this government all year. It is now clear that we have less than a decade to turn greenhouse-gas emissions around if we are to have any chance of stabilising the global climate with in the scientific "safety line" of a 2°C temperature increase. A Brown term (or even worse, two) would put off serious measures such as the in troduction of carbon rationing for longer than either the country or the planet can afford.
Failing a Miliband coup, I hope that Labour loses the next election. Ideally, the Greens would sweep the board - but the party needs to make big changes before it can have serious political credibility: first and foremost, by electing a recognisable leader. At the moment there is a constant muddle of frequently shifting "principal speakers" and even I - a party member - can never remember who they are. And, regrettably, without a fair electoral system, the Greens will never be anything other than a marginal force.
Even so, it should not be forgotten that the group that has made the most challenging recent statement on climate change is not the Green Party, nor even Friends of the Earth: it is the Tories, in the shape of David Cameron's Quality of Life policy group. (Full disclosure: I am an adviser.) Less than a week before Brown's pre-Budget statement, the Conservative group's first report was headlined with the plea: "Don't give up on 2oC." As this column has noted before, both Stern and Sir David King - the government's chief scientific adviser - have, in effect, given up on the two-degree limit, despite the high probability that crossing that threshold will eliminate half of life on earth: a mass extinction that will undoubtedly include a significant proportion of the planet's human population.
The first sentence of the Quality of Life report is spot on, and illustrates what too many seem to have forgotten: when it comes to climate change, "the politics must fit the science and not the other way round". Here, even Friends of the Earth falls down: its current campaign for 3 per cent year-on-year cuts in UK emissions would almost certainly fail to achieve the target of 400-450 parts per million of greenhouse gases in the atmosphere necessary to stay below the two-degree limit (though action jointly with other countries is vital to achieve any target at all).
Yet reports from the Quality of Life group are worth the paper they are written on only if the Conservative Party takes them into its official manifesto come the next election. This will be the Conservative leader's key test. Where Brown has failed, can Cameron now succeed?