A "flat Earth love-in". That's how one MP described the debate he witnessed in parliament last week. The politics with which citizens of the United States, Canada and Australia are now wearily familiar, in which elected representatives denounce both scientific evidence and the researchers who produce it, have arrived in Britain.

A couple of years ago I decided to stop arguing with climate change deniers. It was driving me mad. Spend too much time grappling with the convolutions of people like Nigel Lawson, Christopher Monckton, Mail and Telegraph columnists David Rose and Christopher Booker, and some of it rubs off on you. I began to feel like the man in the celebrated cartoon: "I can't come to bed yet, dear. Someone is wrong on the internet."

But this, in Westminster, is something new: a group of parliamentarians, some of them, like John Redwood, Peter Lilley, Andrew Tyrie and Graham Stringer, senior and experienced, prepared to abandon all caution and declare an all-out war on the evidence. Listening to the debate on Tuesday, I had the sense that they were undergoing an initiation test, like Mara gang members acquiring a facial tattoo. To show you are a true believer, you must disfigure your political record by reciting a ream of nonsense in parliament. So, with a heavy heart, I find myself going in again.

They appeared to have two aims: to torpedo the report being published next week by the Intergovernmental Panel on Climate Change and to strike down the UK's Climate Change Act. Were it not for the fact that they now represent a powerful current of opinion within parliament, in which the environment secretary swims, I would bang my head three times against the wall then move on. But their power and reach, their clanking certainties and outrageous misrepresentations demand a response.

The debate was proposed by a Conservative MP named David TC Davies, who used his speech to produce a long list of conspiracy theories and zombie myths: claims that have been repeatedly debunked but keep resurfacing. Here are a couple of examples, to give you a sense of the distance some of our elected representatives have established between themselves and the evidence.

"It is not proven," Davies said, "that the carbon dioxide that has gone into the atmosphere is responsible for the relatively small amount of warming that has taken place since industrialisation." Well, of course it's not proven – nothing is. But the evidence is impressive. Perhaps Davies is unaware of the mountain of scientific work on the subject, investigating the likely contribution of sunspots, volcanoes and other natural causes, and measuring changes in the amount of radiation reflected back to the Earth's surface by greenhouse gases. These studies attribute most of the warming of the past few decades to us.

Davies insisted that "in the 1970s everyone was predicting a forthcoming ice age". But a study of the peer-reviewed literature on climate change published between 1965 and 1979 found just seven articles suggesting that the world might be cooling, and 44 proposing that it was likely to get warmer. The "emphasis on greenhouse warming", it concludes, "dominated the scientific literature even then". There were several stories in the popular press suggesting an impending ice age but scientists cannot be blamed for that, any more than they can be blamed for Davies's claim that "it is an ice age that we should be worried about".

On he went, churning through familiar fables and wild conspiracies about the role of the Met Office, which "did everything possible to withhold its evidence and calculations" by, er, publishing them on its website. The bastards. But one statement stands out. Davies maintained that according to a parliamentary answer he'd received, "every person in the country will be paying between £4,700 and £5,300 a year towards the government's climate change policies". I looked up the answer. It says nothing of the kind.

The figures he was given are the average per person for all energy costs between 2010 and 2050: "all capital, operating and fuel costs for the whole energy system including cars, trains, planes, power stations, boilers and insulation". Climate change policies account for a very small part of the total. The answer was provided just eight days before the debate. It is hard to understand how Davies could have remembered the figures but forgotten what they represented.

He's not the only one who mangled the evidence like this. The Labour MP Graham Stringer joined the witch-hunt by claiming that the Met Office's research department – the Hadley Centre, based in Exeter – had been discredited by an inquiry led by Lord (Ronald) Oxburgh. But Oxburgh's inquiry investigated (and largely exonerated) a completely different body at the other end of the country: the University of East Anglia's climatic research unit. What makes this really odd is that Stringer, as a member of the Commons science and technology committee, conducted a parallel inquiry into the unit, during which he was noted for his aggressive questioning. How could he have forgotten which body was the subject of these investigations?

Even if we are to believe that these elected representatives have such poor memories or such feeble powers of comprehension, Davies and Stringer both owe the House of Commons a correction.

It was cheering to see a Conservative minister, Greg Barker, mount a robust defence of the science, especially as one of his colleagues, the environment secretary Owen Paterson, has now publicly rejected it, siding with the fossil fuel lobbyists against the evidence. But for how much longer will the government hold the line against the flat-Earthers in its own ranks? Will we soon find ourselves in the position of Australia, with a prime minister who once described manmade global warming as "absolute crap"?

Never underestimate the willingness of powerful people to ignore the evidence they find inconvenient. Never underestimate their willingness to appease industrial lobbyists by repeating the nonsense they generate. Never underestimate their readiness to sacrifice the common interests of humankind for the sake of a belief they refuse to abandon.

Twitter: @georgemonbiot. A fully referenced version of this article can be found at monbiot.com