Leading article: Sceptics have their uses

The climate change sceptics have done us all a favour. This may seem a curious view for a newspaper so committed to the cause of environmental sustainability. But, by challenging the consensus view of global warming, the sceptics have tested the flabbier assumptions of that consensus and forced the proponents of the majority view to sharpen their arguments.

The story began on Friday 13 November last year, when files from a back-up server at the University of East Anglia's Climate Research Unit were copied on to the internet. No one knows how they got there. It may have been no more than a security flaw exploited by a climate change sceptic web geek, but the timing, a month before the Copenhagen summit at which world leaders were to agree action to mitigate global warming, could not have been better scheduled by the opponents of such action.

The files contained emails that suggested that climate scientists had used "tricks" to manipulate the data on warming, and to "hide the decline" in temperatures.

As it happened, the furore over the leaked emails had no effect on what happened at Copenhagen. The failure to reach a more substantial agreement owed more to the dynamics of Chinese politics and culture than to an ideological frenzy on the English-speaking internet. But the media interest in Copenhagen looped back into the sceptical narrative, and has driven it in the weeks since. In those weeks, the sceptics have won two more propaganda victories. First, it turned out that a claim that the glaciers of the Himalayas might melt by 2035, which had been endorsed by the guardians of scientific orthodoxy, the Intergovernmental Panel on Climate Change (IPCC), was unfounded. Then the doubters seized on another IPCC study, which repeated a claim that 40 per cent of the Amazon rainforest might die off, and sourced it to a non-peer-reviewed paper produced for the green pressure group, WWF.

These may seem to be details. Indeed, the Amazon case is a matter of mere sloppy footnoting, as there are peer-reviewed sources for the prediction that 40 per cent of the rainforest could be turned into savannah by only a small rise in average temperatures. But details matter.

They matter because they provide fuel for the sceptics' propaganda, which has in turn had a marked effect on public opinion. A Populus survey for the BBC in November found that 83 per cent of respondents thought that "the Earth's climate is changing and global warming taking place", with only 15 per cent disagreeing. That had changed last week to 75 per cent agreeing and 25 per cent disagreeing. This was trumpeted by the Daily Mail yesterday under the headline, "How our belief in global warming is draining away." It might be thought that the striking thing about the poll finding is that the public continues to accept the threat of climate change by such an overwhelming margin.

Details also matter because rigour and transparency are important. The sceptics have a point, when they suggest that the very fact of the overwhelming consensus among scientists had induced a form of groupthink, institutionalised by the IPCC. This seems to have meant that the scientists at the University of East Anglia became more concerned with what their data looked like than with its evidential value. For that, as for so much else in public policy, openness is the answer. However, if transparency is to be enjoined on the scientists, it must also apply to the ideologues, business interests and genuine sceptics that are seeking to persuade us that human-made climate change is a myth.

That is why our special report today seeks to hold up to public view the networks and the oil industry funding that sustain the propaganda effort against the consensus that has developed over the past four decades by the cumulative process of testing the theory against the evidence. Thus we should be grateful to sceptics, even if the cult-like belief in conspiracy theory of many of them gives the healthy instinct of scepticism a bad name.

After the past three months, it must be expected that the science will now be presented in a way that it is more robust, and more focused on the need to rebut the populist myths of the so-called sceptics. Openness on both sides will, we believe, only strengthen popular understanding that the climate is affected by human activity, and that the need for a collective policy response is urgent.