This Friday, the Intergovernmental Panel on Climate Change (IPCC) is set to publish the first instalment of its three-part, 2,000-page draught-excluder, the memorably titled Fifth Assessment. This, like its predecessor, which was published at the height of climate-change mania in 2007, will tell us ‘unequivocally’ that climate change is happening, that the situation is perilous, and that there is a sliding scale of bad scenarios awaiting us in the warmed-up future.

As such, the prophecies leaked from the draft version sound a comfortably familiar note of terror, like the ever-resurrected bad guy in a tired horror-movie franchise. We’ll be told that the glaciers are melting quicker than thought, that sea levels could rise by three feet and that temperatures could rise by up to 4.8 degrees Celsius this century. And, on the back of The Science, the old alarmist lags have once again been demanding that we do something. In the words of Lord Stern, author of the environmentally friendly The Stern Review in 2006, we need to decide what ‘kind of world we want to present to our children and grandchildren’. That is, one scorched by our present greed or saved by our cutting back. That’s the point of the IPCC’s infrequent assessments. They constitute the Word of a very secular God, the expert, the scientist. They tell us what we ought to do. No questioning. No debate. And therefore, no politics.

But there’s one big fat sceptical fly stuck in the IPCC’s ointment. And that’s the small matter of a distinct absence of global warming over the past 15 years, despite the IPCC’s models insisting otherwise. In December 2012, for instance, the UK Met Office released a forecast, suggesting not only had global temperatures not risen for over a decade, but also that they were unlikely to rise significantly in the period up to 2017. Likewise, earlier this year, even someone as committed to climate-change alarmism as James Hansen, the recently retired head of NASA’s climate-change research arm, admitted that the ‘five-year-mean global temperature has been flat for the last decade’. In the draft version of the report, the IPCC does acknowledge that the ‘the rate of warming over the past 15 years is smaller than the trend since 1951′. In fact, the IPCC now admits that the rate of warming between 1998 and 2012 was about half the average rate since 1951. And as it stands, no one is quite certain why this is, with everything from the oceans’ ability to absorb heat to the solar cycle being blamed.

This admission poses a problem for the politicians and campaigners who have been busy using The Science, with the IPCC its chief vessel on Earth, to justify their political visions. It looks as if things are not as straightforward as they have desperately been wanting us to believe. Little wonder then, as the Associated Press reports, that several governments have been objecting to the way the global-warming ‘pause’ has been presented by the IPCC. Germany, with the distinctly green Chancellor Merkel at the helm, wanted any reference to the slowdown in global warming to be deleted; the US wanted everything to be attributed to an oceanic heat transfer; and Belgium was annoyed that 1998 was registered as the start of the ‘pause’ because, well, the government felt it was really hot that year. For critics – variously described by climate-change advocates as ‘sceptics’ or even ‘deniers’ – the IPCC’s problems, and the palpable interference of governments in what is often presented as a purely science-led process, shows that the science is not really as scientific as is made out. Rather, say the critics, the science has been compromised by politics: it has been politicised.

In a way, of course, this is true. The status of the IPCC’s reports as the unvarnished truth, to be acted upon by governments and citizens alike, has always been a myth. For a start, the IPCC, and those closely associated with its championing, are not exactly experts in climatology. Lord Stern, for instance, is an economist, and the chairman of the IPCC, Rajendra Pachauri, is a railway engineer. Moreover, as the Fourth Assessment revealed, the research, such as it was, was too often made to fit the global-warming agenda rather than to determine it. This was exemplified by a falsehood about Himalayan glaciers melting in just a few decades that was lifted from New Scientist magazine rather than peer-reviewed studies. Indeed, as Canadian journalist and author Donna Laframboise told spiked in 2012, 30 per cent of the references in the Fourth Assessment were from newspaper and magazine articles, unpublished master’s theses, reports produced by green groups, and even press releases. The IPCC’s science was selected to fit the argument, not the other way around. But there’s a bigger problem here than the IPCC’s consistently dodgy science, underpinned by behind-the-scenes politicking. Because while it’s partially right to say that the IPCC has always been a thoroughly politicised institution, rather than a purely scientific one, that isn’t the main issue. The important thing to grasp is that the IPCC has acquired this role, this supreme policy-determining function, in the absence of politics proper. The science of climate change has, over the past two decades, become a substitute for political argument, a means to justify and legitimate policies and politicians. Whereas once a political vision, an idea of the good life, might have guided a set of policies, now it is The Science, and a modelled idea of the not-so-good life, which determines policies. Climate-change science is therefore called upon to fill in the big ideas-shaped hole at the heart of contemporary public and political life. It is there to tell us, and our rulers, what to do. The IPCC exists because of a profound political need for it to.

The problem, then, is not that the IPCC is too political. Rather, it’s that the debate about the future, about what kind of society we want to live in, is not political enough. Just as facts cannot give rise to values, the science will never be able to tell us what we ought to do. That remains a question for the people, not the experts. Tim Black is deputy editor of spiked.