We all create our own reality, and shut out the voices we do not want to hear. But there is no issue we are less willing to entertain than man-made climate change. Here, three worlds seem to exist in virtual isolation. In the physical world, global warming appears to be spilling over into runaway feedback: the most dangerous situation humankind has ever encountered. In the political world - at the climate talks in Poznan, for instance - our governments seem to be responding to something quite different, a minor nuisance that can be addressed in due course. Only the Plane Stupid protesters who occupied part of Stansted airport yesterday appear to have understood the scale and speed of this crisis. In cyberspace, by contrast, the response spreading fastest and furthest is flat-out denial.

The most popular article on the Guardian's website last week was the report showing that 2008 is likely to be the coolest year since 2000. As the Met Office predicted, global temperatures have been held down by the La Niña event in the Pacific Ocean. This news prompted a race on the Guardian's comment thread to reach the outer limits of idiocy. Of the 440 responses posted by lunchtime yesterday, about 80% insisted that manmade climate change is a hoax. Here's a sample of the conversation:

"This is a scam to get your money ... The only people buying into 'global warming' have no experience with any of the sciences."

"If we spend any money or cost one person their job because of this fraud it would be a crime. When will one of our politicians stand up and call this for what it is, bullshit!"

"What a set of jokers these professors are ... I think I understand more about climate change than them and I don't get paid a big fat salary with all the perks to go with it."

And so on, and on and on. The new figures have prompted similar observations all over the web. Until now, the "sceptics" have assured us that you can't believe the temperature readings at all; that the scientists at the Met Office, who produced the latest figures, are all liars; and that even if it were true that temperatures have risen, it doesn't mean anything. Now the temperature record - though only for 2008 - can suddenly be trusted, and the widest possible inferences be drawn from the latest figures, though not, of course, from the records of the preceding century. This is madness.

Scrambled up in these comment threads are the memes planted in the public mind by the professional deniers employed by fossil fuel companies. On the Guardian's forums, you'll find endless claims that the hockeystick graph of global temperatures has been debunked; that sunspots are largely responsible for current temperature changes; that the world's glaciers are advancing; that global warming theory depends entirely on computer models; that most climate scientists in the 1970s were predicting a new ice age. None of this is true, but it doesn't matter. The professional deniers are paid not to win the argument but to cause as much confusion and delay as possible. To judge by the Comment threads, they have succeeded magnificently.

There is no pool so shallow that a thousand bloggers won't drown in it. Take the latest claims from the former broadcaster David Bellamy. You may remember that Bellamy came famously unstuck three years ago when he stated that 555 of the 625 glaciers being observed by the World Glacier Monitoring Service were growing. Now he has made an even stranger allegation. In early November the Express ran an interview with Bellamy under the headline "BBC shunned me for denying climate change". "The sad fact is," he explained, "that since I said I didn't believe human beings caused global warming I've not been allowed to make a TV programme." He had been brave enough to state that global warming was "poppycock", and that caused the end of his career. "Back then, at the BBC you had to toe the line and I wasn't doing that."

This article, on the web, received more hits than almost anything else the Express has published; so 10 days ago the paper interviewed Bellamy again. He took the opportunity to explain just how far the conspiracy had spread. "Have you noticed there is a wind turbine on Teletubbies? That's subliminal advertising, isn't it?"

There is just one problem with this story: it is bollocks from start to finish. Bellamy last presented a programme on the BBC in 1994. The first time he publicly challenged the theory of manmade climate change was 10 years later, in 2004, when he claimed in the Daily Mail that it was "poppycock". Until at least the year 2000 he supported the theory.

In 1992, for instance, he signed an open letter, published in the Guardian, urging George Bush Sr "to fight global warming ... We are convinced that the continued emission of carbon dioxide at current rates could result in dramatic and devastating climate change in all regions of the world." In 1996 he signed a letter to the Times, arguing: "Continued increases in the global emissions of carbon dioxide from the burning of fossil fuels are likely to lead to climate change at a rate greater than the Earth has experienced at any time during the last 10,000 years." In the same year he called for the replacement of fossil fuels with wind power. In 2000 he announced that he was supporting a plan to sue climate change "criminals": governments and industries that blocked attempts to stop global warming (all references are on my website). But Bellamy's new claims about the end of his career have been repeated as gospel in several newspapers and all over the web.

In his fascinating book Carbon Detox, George Marshall argues that people are not persuaded by information. Our views are formed by the views of the people with whom we mix. Of the narratives that might penetrate these circles, we are more likely to listen to those that offer us some reward. A story that tells us that the world is cooking and that we'll have to make sacrifices for the sake of future generations is less likely to be accepted than the more rewarding idea that climate change is a conspiracy hatched by scheming governments and venal scientists, and that strong, independent-minded people should unite to defend their freedoms.

He proposes that instead of arguing for sacrifice, environmentalists should show where the rewards might lie: that understanding what the science is saying and planning accordingly is the smart thing to do, which will protect your interests more effectively than flinging abuse at scientists. We should emphasise the old-fashioned virtues of uniting in the face of a crisis, of resourcefulness and community action. Projects like the transition towns network and proposals for a green new deal tell a story which people are more willing to hear.

Marshall is right: we have to change the way we talk about this issue. You don't believe me? Then just read the gibberish that follows when this article is published online.



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