Lord Turnbull, the former head of the UK civil service, says the government must push for new leadership of the Intergovernmental Panel on Climate Change (IPCC).
He says new leaders are needed to re-build trust in climate science following the "Climategate" e-mails affair and the IPCC's glacier mistake.
Lord Turnbull made his comments in a report on Climategate published by the climate-sceptic think-tank the Global Warming Policy Foundation (GWPF), of which he is a trustee.
The government has not yet said whether it will use its influence to seek new leadership of the IPCC.
A change at the top of IPCC was implicitly recommended in a recent review by the InterAcademy Council (IAC), which represents the world's leading science academies.
The report said the IPCC's leadership should serve no more than one term of office; but the current chairman, the Indian engineer and economist Professor Rajendra Pachauri, is already into his second term.
Professor Pachauri has faced relentless attack from climate sceptics for several years. He has been increasingly outspoken about the increase in emissions of the greenhouse gases that are accepted by almost all scientists to have warmed the planet.
But he was widely blamed for a delay in addressing the IPCC's error over the projected date for the melting of Himalayan glaciers.
I understand that privately he believes the glacier error is being used by industry-sponsored campaigners as another stick to beat him. And when asked about his future at the launch of the InterAcademy Council report, he replied ambivalently.
His future will be determined by a meeting of the IPCC at Busan, in South Korea, next month, where government delegates will make key decisions about reforming the panel.
The UK has previously been a major actor at the IPCC. One expert close to government told BBC News the decision might be influenced by the desire of Prime Minister David Cameron not to undermine UK relations with India.
I understand that France will not seek Professor Pachauri's resignation. And if India decides to make this an issue of national pride, it will be hard for other major nations to put in a challenge.
But critics will argue that credibility of the IPCC itself will be undermined if governments fail to act on all the reforming recommendations of the IAC - and that includes finding a new leadership to continue work on the panel's next assessment report, the AR5, expected around 2015.
In a foreword to the Global Warming Policy Foundation report, Lord Turnbull says: "The government should demand that the changes recommended by the IAC in practice, governance and leadership should be implemented immediately for the Fifth Assessment."
Later he told BBC News: "It is crystal clear that the IAC intends Professor Pachauri to go now."
Commenting on the troubles faced by the IPCC and the University of East Anglia (UEA) - which was at the heart of the Climategate affair - the UK's former top mandarin warned: "Gone are the times when the 'authorities' could largely assert their message without challenge using their superior resources, and thereby ensure that difficult issues remain hidden.
"We increasingly live in the world of Erin Brockovich versus Pacific Gas and Electric, where committed individuals with few resources can dig away at an issue.
"Armed with strengthened rights to information and the forensic power of the internet they will eventually get to the truth, and quick but superficial inquiries will not stand in their way."
The e-mails issue came to light in November last year, when hundreds of messages between CRU scientists and their peers around the world were posted on the internet, along with other documents.
Critics said the e-mail exchanges revealed an attempt by the researchers to manipulate data and three independent reviews were initiated into the affair. None of these reviews found evidence of scientific malpractice.
Andrew Miller, chairman of the House of Commons Science & Technology Committee, who was not involved in the GWPF report, agreed that the IAC's recommendations on changing leadership of the IPCC should be taken very seriously.
"Any decision about the chairman of IPCC must be taken for the sole reason of restoring confidence in the IPCC," he told BBC News.
"Political considerations must not play a part in whether the chairman should stay in post or not."
He indicated that his committee would make further investigations into conduct at the University of East Anglia.
But he rejected a separate demand from Lord Turnbull for a parliamentary review of climate science. "Lord Lawson (founder of the GWPF) appears to be trying to re-write the basics of climate science, but neither science committee in the Commons or Lords would waste its resources on such a futile task," he said.
"The vast majority of scientists round the world accept that climate change is a critically important issue, and it is almost always non-scientists who want to argue about that."
The new GWPF report is written by the climate-sceptic blogger and author Andrew Montford.
He concludes that the enquiries into Climategate were inadequate and will be unlikely to restore public confidence in the work of the Climatic Research Unit (CRU) at UEA.
His report complains that the enquiries commissioned by UEA did not offer sceptics the chance to give oral evidence. He points to many instances where he says the enquiries failed properly to investigate serious allegations against academics at UEA.
A UEA spokesman said: "Three independent reviews have found in favour of the integrity and honesty of the scientists in the Climatic Research Unit. CRU's published outputs have been subject to expert peer review for more than three decades and remain open to scrutiny by anyone.
"Each of the reviews was independent of the university and one was conducted by a committee of the House of Commons.
"We would observe that the GWPF report appears to offer nothing new or previously unavailable, and that it has failed to acknowledge the further exhaustive examination undertaken by the US Environmental Protection Agency (published 29 July 2010) which also found no evidence to support the allegations made against CRU."