Dr Rajendra Pachauri, the chairman of the Intergovernmental Panel on Climate Change (IPCC), also apologised for describing as "voodoo science" an Indian government report that challenged the IPCC's claims about the rapid melting of Himalayan glaciers.
70-year-old Pachauri, the Director General of New Delhi-based The Energy and Resources Institute, said he now plans to adopt a neutral advisory role and focus in future on presenting the science on climate change rather than advocating policies.
On the IPCC's tardiness in responding to complaints and correcting errors - such as its claim that all Himalayan glaciers would disappear by 2035 - he said: "Our response has been much too late and much too inadequate."
Claiming support of all the world's governments, Pachauri rejected calls for his resignation and insisted he would remain as chairman until after publication of the IPCC's next report in 2014.
He denied that by remaining in post, he was undermining the IPCC's chances of regaining credibility with the public. "It is not correct to say there are people who don't trust me", Pachauri told The Times newspaper.
He admitted that it had been a mistake to give the impression, in many interviews, that he was advocating specific actions to cut emissions.
Last year he called for higher taxes on aviation and motoring, and advised people to eat less meat. He also proposed that hotel rooms should have electricity meters to charge people extra for using air conditioning.
"I will try to clarify that I'm not prescribing anything as a solution. Maybe I should be more careful (in media interviews) in laying down certain riders. One learns from that and I'm learning," said the head of the IPCC, which shared the 2007 Nobel Peace Prize with former US Vice President Al Gore.
Of his "voodoo science" comment, Dr Pachauri said: "It was an intemperate statement. I shouldn't have used those words. I have to show respect to people who have worked on a particular subject."
He said the review of the IPCC announced this month would not consider his role or his actions. The review, by a panel drawn from the world's leading science academies, will only consider the IPCC's procedures.
Pachauri said he wanted more power over the IPCC secretariat and an extra USD 1 million a year to fund its work, on top of the USD 5 million it already receives.
The IPCC is planning to recruit more staff to help it to promote its work and defend itself against attacks by climate sceptics.
On the issue of conflict of interest as the chief of TERI, the British daily said a report had found that there was no evidence of "personal fiduciary benefits" to Pachauri.
"No evidence was found that indicated personal fiduciary benefits accruing to Pachauri from his various advisory roles that would have led to a conflict of interest," the Times quoted a KPMG report as saying.