Dr Rajendra Pachauri, chairman of the Intergovernmental Panel on Climate Change, apologised for the way his organisation handled complaints about mistakes in its report, and for criticising an opposing piece of research as "voodoo science".
But he also accused politicians and prominent critics of "a new form of persecution" against scientists who support the conept of global warming.
It had been incorrect to give the impression, in media interviews, that he was advocating specific actions such as green taxes to combat climate change.
"I will try to clarify that I'm not prescribing anything as a solution," he said.
"Maybe I should be more careful (in media interviews) in laying down certain riders. One learns from that and I'm learning."
The IPCC has been accused of moving too slowly to correct errors in its reports on climate change, which played a significant role in last year's Copenhagen summit.
For example, it wrongly claimed that all Himalayan glaciers would disappear before 2035 even though its mistake had been pointed out before the summit began.
Dr Pachauri said: "Our response has been much too late and much too inadequate."
A report by the Indian government which undermined the IPCC's glacier statement was attacked as "voodoo science" by Dr Pachauri, but he has now conceded that it was an "intemperate statement" and that he "should not have used such words".
Dr Pachauri, 70, dismissed calls fro his resignation and insisted he woudl remain IPCC chairman until after the publication of its next report in 2014.
In February The Sunday Telegraph disclosed a series of factual errors and poor sources of evidence in the IPCC's influential report to government leaders.
Dr Pachauri said in an article for The Guardian: "I sincerely hope the world is not witnessing a new form of persecution of those who defy conventional ignorance and pay a terrible price for their scientifically valid beliefs."