Although sceptics have been gnawing away at the credibility of climate science for years, over the last five months they have made enormous leaps owing to the hacking of emails from the Climate Research Unit at the University of East Anglia and the discovery of a number of alleged mistakes in the benchmark reports of the IPCC.



While the "revelations" have been milked for all they are worth, and a lot more, the science remains rock solid. If instead of cherry-picking two or three that lend themselves to spin, you read the 1000 or so emails that were posted on a Russian server the picture that emerges is one of an enormously dedicated group of men and women doing their best to carry out research of the highest quality.



If there were a conspiracy among scientists to manipulate the truth, you would expect the evidence to be there in spades in these private emails. But it's not. Instead they show scientists working their backsides off to do good science, with email exchanges stopping briefly on Christmas Eve to be resumed on Boxing Day, with apologies to colleagues for taking time out to have surgery or get married, all with a sub-text of worry about the implications of their work for the future of humanity.



Rather than cover-ups, we read private emails from one scientist to Phil Jones, the CRU head who has been forced to step down pending an inquiry, saying he has been watching the sceptics blogs and, anticipating misrepresentation, says "this last aspect needs to be tackled more candidly in AR4 than in the SOD, and we need to discuss how to do this". Others show them bending over backwards to be open.



Before the leak of the CRU emails, one colleague emailed others in response to attacks by sceptics on Phil Jones:



"The sad thing here is that Phil Jones is one of the true gentlemen of our field. I have known Phil for most of my scientific career. He is the antithesis of the secretive, "data destroying" character the CEI and Michaels are trying to portray to the outside world."



And the emails reveal the enormous external pressure they were under. They show they were constantly accused of being frauds and cheats; their work was twisted and misrepresented; and they were bombarded with vexatious freedom of information requestsorchestrated by denialists. In short, they were caught up in a hot political debate that they did not really understand or want to be part of, yet they were the target of savvy, secretive and ruthless organisations ready to pounce on anything they said or wrote.



This is the real story exposed of "Climategate". Instead, the scientists in question have seen their professional reputations trashed in the world's media for no cause, to the point where Phil Jones has been on the verge of suicide. It has been the most egregious and unfounded attack on the integrity of a profession we have ever seen.



Yet the science remains rock solid



Since the leaking of the CRU emails the worldwide press have reported a series of "mistakes" in the IPCC reports that have allowed the denial lobby to claim that the entire IPCC process and the body of climate science should be junked. It turns out that almost all of the mistakes are fabrications. How could this have happened?



The first and only significant error identified in the IPCC report is the claim that 80 per cent of Himalayan glaciers are very likely to disappear by 2035. This was a serious mistake for a scientific report that should not have got through the review process. But let's be very clear about its significance:



The error occurred in Volume 2 of the Fourth Assessment Report (AR4), the volume on the impacts of climate change. Volume 1 reports and assesses the physical basis for climate science, including projections of warming. Chapter 4 contains an extensive discussion of glaciers, snow and ice. Projections for glaciers are also discussed in Chapter 10. No one has challenged any of the statements in these chapters, prepared by teams including the world's leading glaciologists, which carefully lay out what is known.



The error occurred in Volume 2 of the Fourth Assessment Report (AR4), the volume on the impacts of climate change. Volume 1 reports and assesses the physical basis for climate science, including projections of warming. Chapter 4 contains an extensive discussion of glaciers, snow and ice. Projections for glaciers are also discussed in Chapter 10. No one has challenged any of the statements in these chapters, prepared by teams including the world's leading glaciologists, which carefully lay out what is known. The erroneous "2035" claim was nowhere highlighted by the IPCC. It appeared neither in the chapter summary, the report summary or the crucial Summary for Policymakers. In no sense was it a central claim of the IPCC report, as some newspapers have said.

The erroneous "2035" claim was nowhere highlighted by the IPCC. It appeared neither in the chapter summary, the report summary or the crucial Summary for Policymakers. In no sense was it a central claim of the IPCC report, as some newspapers have said. It was a glaring error that should have been picked up earlier, but it was so deeply buried in the report that denialists around the world, with all of their supposed scientific expertise, did not pick it up for two years. In fact, they did not pick it up at all; it was first pointed out by Georg Kaser and others. Kaser is an eminent glacier expert who was a lead author of Chapter 4 in Volume 1.

Although mistakes like this one should not occur, to suggest that it has any bearing on the credibility of the science of AR4 is absurd. The more remarkable fact is that so few errors have been identified in AR4, and none at all in the crucial Volume 1 which sets out the physical basis for climate change. On page 493 of Volume 2, where the "2035" mistake occurs, I count 20 factual claims that are falsifiable. Multiply that by the 3,000 or so pages in AR4 and you can see how utterly trivial that single mistake is.



But haven't many more mistakes been found in AR4? No. The only other claimed error that has any substance is the statement that "55% of its [the Netherlands] territory is below sea-level". This figure was supplied by the Dutch Government. It is slightly misleading because the correct statement is that 55% per cent of the Netherlands is at risk of flooding,although the Dutch Ministry of Transport says that 60% of the country is below the high water level. The confusion may have implications for the Netherlands' dike planning but has no bearing whatever on the science of climate change.



There are three additional "errors" in AR4 that have attracted press attention and sparked denialist frenzies. They are analysed on the Realclimate website.



"Africagate" refers to the claim that AR4 overstated the potential decline in crop yields in Africa. The figures in AR4 have since been shown to be an accurate assessment.

"Africagate" refers to the claim that AR4 overstated the potential decline in crop yields in Africa. The figures in AR4 have since been shown to be an accurate assessment. "Disastergate" is the allegation that the IPCC erroneously attributed some of the rising costs of disasters to climate change. In fact, the section in question is hedged around with caution and the expert whose work was said to be misused by the IPCC has declared that the IPCC has fairly represented his findings.

"Disastergate" is the allegation that the IPCC erroneously attributed some of the rising costs of disasters to climate change. In fact, the section in question is hedged around with caution and the expert whose work was said to be misused by the IPCC has declared that the IPCC has fairly represented his findings. "Amazongate", a story that opened with the claim: "A startling report by the United Nations climate watchdog that global warming might wipe out 40% of the Amazon rainforest was based on an unsubstantiated claim by green campaigners who had little scientific expertise". The story is plain wrong, with the expert on whose work the IPCC relied stating that the information is correct, although the referencing is incomplete.

Apart from the fact that these three "gates" are beat-ups with no basis in their criticism of the IPCC, they have one feature in common - the stories were all written by Jonathan Leake, science and environment editor of The Sunday Times.



Leake has close links with deniers and in fact based these stories directly on wild and unsubstantiated claims by sceptic bloggers, as uncovered by Tim Holmes. In the case of Amazongate, Leake had been informed by another expert that, while the referencing was inadequate, the claim in AR4 is correct and, if anything, an understatement. But Leake disregarded this and quoted that same expert in his story to exactly the reverse effect, as if he were a severe critic of the IPCC.



On the role of Leake I can do no better than quote Tim Holmes:



"While it is wholly unsurprising that the denial lobby should be attempting to push baseless and misleading stories to the press, what is surprising is the press's willingness to swallow them. In this case, two experts in the relevant field told a Times journalist explicitly that, in spite of a minor referencing error, the IPCC had got its facts right. That journalist simply ignored them. Instead, he deliberately put out the opposite line - one fed to him by a prominent climate change denier - as fact. The implications are deeply disturbing, not only for our prospects of tackling climate change, but for basic standards of honesty and integrity in journalism."



Leake's stories have been reproduced in the other Murdoch broadsheets, The Australianand the Wall Street Journal and of course have been amplified on Fox News, and are themselves now being referred to as "Leakegate".



Bloggers and columnists, who attack climate science without ever opening an IPCC report or speaking to a real climate scientists, imagine that the body of climate science is a house of cards, and taking away one or two will cause it to collapse. In fact the scientific case for global warming is like a mountain built up by adding one rock at a time over many years. Even if all of the alleged errors were true it would amount to picking off a handful of rocks from the top of the mountain, leaving the rest unchanged and unmoved.



Yet these alleged mistakes - non-existent or trivial - with no implications whatever for the robustness of climate science have been deployed in a sophisticated campaign to blacken the reputations of the scientists responsible for alerting us to the perils of global warming.



Perception versus reality



Unfortunately, the chorus of declarations that the climate scientists got it wrong has had no impact on the earth's climate. Indeed, those who study the climate itself rather than the bogus debate in the newspapers and the blogosphere understand that climate science and popular perceptions of climate science are diverging rapidly, not least because the news on the former is getting worse.



Soon after AR4 appeared in early 2007, those familiar with the science began to say that as a result of the consensus process and the natural caution of scientists, the Fourth Assessment Report had seriously understated the risks from climate change, particularly in its selection of scenarios and its estimates of likely sea-level rise.



Rather than rehearse the evidence for these warnings, well known to those who follow the science, let me make mention of a number of developments in climate science that have been published or reported in the five months since the leaking of the Climategate emails. It is evidence that warming is more alarming than previously thought yet which has been buried in the avalanche of confected stories claiming that climate scientists have exaggerated.



I have tried to find some new studies that go the other way in the hope I can counterbalance this bleak story, but have not succeeded.



Over the last five months, a vast gulf has opened up between the media-stoked perception that the climate science has been exaggerated and the research-driven evidence that the true situation is worse than we thought.



Just when we should be urging immediate and deep cuts in global greenhouse gas emissions, the public is being lulled into disbelief, scepticism and apathy by a sustained and politically driven assault on the credibility of climate science. For this we will all pay dearly.



Tomorrow: Where are the defenders of science?

