"I believe this incident on Himalayan glaciers might contribute to increasing the credibility of the IPCC," the deputy chief said. He stressed that no human institution is infallible, but if it can admit to its mistakes and learn from them, then this should only enhance its reputation.
Jean-Pascal van Ypersele said the IPCC's claim that Himalayan glaciers were in danger of disappearing by 2035 was not in line with the panel's own review procedures.
"In this particular instance, an error had been made and procedures had not been followed," he said. He explained that the reviewers did not have enough time to invest in producing this part of the report, but was quick to stress that the review process had been strengthened last autumn.
The organisation was forced to admit its mistake after an article in New Scientist revealed that the year 2035 did not come from peer-reviewed scientific literature but was first put forward in an interview in 1999 by Indian glaciologist Syed Hasnain. The year resurfaced in a 2005 report by conservation group WWF, which is cited in the IPCC's 2007 report.
However, Van Ypersele downplayed the implications of the mistake, saying that it was only one page of a 938-page report and had "not [been] given a lot of visibility". It did not feature in the glaciology chapter but in the Asia chapter, which is much further into the report and is not highlighted in the summary for policymakers, he added.
Van Ypersele said a 2006 email from Austrian glaciologist Georg Kaser, who noticed the error, had not reached the right person.
"He provided correct information but not to the correct person at the correct time," Van Ypersele lamented, adding that the most severe criticism had come after the plenary at which the report was finalised. "It is a combination of very unfortunate things."
Pachauri under fire
IPCC chairman Rajendra Pachauri has come under pressure to resign as a result of the blunder. Pachauri also finds himself under scrutiny over his personal finances amid accusations that he made a profit from his work on climate change.
Van Ypersele fended off the accusations. "He really does not have a life that you could envy," he said, adding that Dr. Pachauri has dedicated his life to his work and was always travelling and lecturing.
Despite admitting that Pachauri's dismissal of the Indian report questioning the melting rate of the Himalayan glaciers as voodoo science "was not ideal," he said it was impossible for someone who gives speeches all the time to avoid making occasional mistakes.
John Schellnhuber, who advises the German government on climate change, joined Van Ypersele in insisting that accusations that Pachauri profits financially from his work are unfounded.
"It is pathetic to ask Dr. Pachauri to step down just because of the Himalayan glacier thing," Schellnhuber said. "He lives like a monk in India, and all the money he receives, he gives to his foundation."
Nevertheless, Schellnhuber said the IPCC would have to reconsider its use of literature.
"There is the question of 'grey literature'," he said. In the past, the organisation has tried to use every possible source for the sake of being comprehensive, rather than aiming for strict quality control.
The IPCC researchers were speaking at a Tipping Point conference in Brussels bringing scientists and artists together to fight climate change.
Despite supporting arts, van Ypersele stressed that he has always maintained the difference between his role as the vice-chairman of the IPCC and the "role of a militant".
"I am trying to be very careful not to bring the IPCC, which is supposed to be policy-relevant, into a policy prescriptive role," he said.