The time is up,” says a top UN official as 192 nations begin their meeting on Monday at the Bella Centre to come to an agreement on climate change. He also mentions that challenges to the credibility of climate change science would not undermine the summit.

The executive secretary of the United Nations framework convention on climate change, Yvo de Boer, said on Sunday that Copenhagen could be a turning point because there had been “unprecedented” acceptance among nations to take action. He mentioned that, with China and India offering to reduce the intensity of their emissions, the condition was different from any time in the past 17 years for a successful outcome of what is called the conference of parties, or COP-15.

“Within two weeks, governments must give their adequate response to the urgent challenge of climate change,” he said, adding that “negotiators now have the clearest signal ever from world leaders to craft solid proposals to implement rapid action.”

The meeting in Copenhagen has been organised by the UN framework.

Leaked emails from the University of East Anglia have left the scientific community in a disarray, in the run- up to the conference, as claims were made that key climate data were manipulated. De Boer said that whenever there was a challenge to the quality of science, it must be addressed. The inter-governmental panel on climate change would do just that.

He said he had spoken to the panel chairman, R K Pachauri, and the latter had told him that he would talk about it during his address before the plenary session of the summit on Monday. He said the panel had gone through a “robust process” of peer review and about 2,500 scientists had looked at works of others to come to the conclusion about climate change in their fourth assessment report.

Nevertheless, the leakage of the emails has cast a shadow on the credibility of the panel and the summit.

De Boer said three points under negotiation at the summit would decide how successful the meeting turned out to be. But what was crucial was the amount of money that must be committed upfront so that climate change work could begin right after the conference.

“What we need as quick start money is $10 billion each for three years from 2010 to 2012,” he said, adding that the developed nations must commit to this amount. In the long run, de Boer said, hundreds of billions of dollars would be needed for mitigation and adaptation.

The three layers of action, according to de Boer, included ambitious commitments to cut and limit emissions by developed nations, immediate funding and a long-term funding commitment and a long-term shared vision on a low-emission future for all.