The Intergovernmental Panel on Climate Change has listened to and learned from recent criticism, but the threat of global warming is real and must be tackled, the group's head said Saturday.

Rajendra Pachuari, the embattled head of the Nobel Peace Prize-winning panel of experts, has been criticized for endorsing climate projections based on faulty or inaccurate evidence.

"There's been a lot of talking about climate change. It's an area under strict scrutiny," he acknowledged at a panel discussion at the annual meeting of the Inter-American Development Bank.

"We at the IPCC, we've listened, we've learnt, we've done something about it."

He defended the panel's much-criticized fourth assessment report, which he said "has a great deal of robust material and findings."

The report has been pilloried for claiming erroneously that the Himalayan glaciers were in imminent danger of melting and the group has also been forced onto the offensive by a series of email exchanges made public by a hacker that appear to show climate experts seeking to hide or misrepresent evidence.

Joining Pachuari was Yvo de Boer, the United Nations official who headed efforts to secure a new international agreement on climate change, but announced his resignation after a major summit on a new deal in Copenhagen last year.

De Boer urged progress in the follow-up summit to Copenhagen, to be held in Cancun in November.

He said funding for the fight against climate change would be a major hurdle to address, and warned that a proposed 100-billion-dollar fund to help developing nations tackle global warming would be difficult to fund solely through contributions from rich nations.

"There's a large perception, especially in the developing world, that the entire 100 billion, it's going to come from public financing. I think that extremely unlikely, I don't see industrialized countries... mobilizing another 100 billion a year for climate change," he said.

He also said the Cancun conference would need to address the challenge of managing and distributing funds.

"If in Mexico we can make a significant advance in terms of addressing the resources mobilization, the resources management and the resources disbursement challenges in a way that effectively blends public and private finance towards the development priorities of developing countries, we'll probably have resolved the most difficult issue in this entire process."