What a difference three months makes. Back in November, the world broadly agreed that emissions of carbon dioxide were heating up the planet and that we needed to do something about it, even if we couldn't agree exactly what. And though we'd had the usual pre-summit rollercoaster ride of dire predictions and naive exhortations (yes, I plead guilty to some of those), even hardheaded types dared to hope that Copenhagen might produce the basis of a global climate treaty.

As late as December 7, 56 newspapers around the world could declare in in a common, Guardian-led editorial: "The politicians in Copenhagen have the power to shape history's judgment on this generation: one that saw a ­challenge and rose to it, or one so stupid that we saw calamity coming but did nothing to avert it."

Now, with climate science under siege and climate politics in disarray, that sounds like the rhetoric of another age. The American commentator Walter Russell Mead recently captured the mood: "The global warming movement as we have known it is dead … basically, Sarah Palin 1, Al Gore zip." A senior British diplomat compares those trying to secure global action on climate change post-Copenhagen to "small groups wandering in different directions around the battlefield like a beaten army". A leading scientist offers an equally pithy assessment: "Everybody is completely clueless."

Not depressed yet? This weekend a BBC poll showed a dramatic fall in the number of people who believe warming is happening; carbon markets have ­tumbled; a Guardian survey of over 30 leading figures involved in climate negotiations found almost none who believed a global deal was possible this year; in Australia a man who described climate change as "absolute crap" could soon be prime minister.

What went wrong? How long have you got: the leak of the "climategate" emails that showed scientists behaving just as tribally as their detractors, the ­Intergovernmental Panel on Climate Change's great ­glacier meltdown (enough "gates" for now), the abject failure of ­Copenhagen, Obama's Massachusetts disaster and a bitterly cold winter in much of Europe and the U.S. If you doubt the effect of the last of these, take a look at stories like "The mini-ice age starts here" in the Daily Mail, or the website entitled If Global warming Is Real Then Why Is It Cold?. Add to that lot a mildly hysterical binary culture in which the case for action on climate change is either unanswerable or in tatters, and the perfect storm is complete.