"You cannot possibly keep waiting forever for new evidence of global warming to act," Rajendra Pachauri, head of the Intergovernmental Panel on Climate Change (IPCC), said on the sidelines of the UN climate talks in Durban.

The 12-day marathon, ending on Friday, seeks to limit warming to 2.0 Celsius (3.6 degree Fahrenheit), a commonly-accepted danger threshold.

Underpinning this goal is a raft of scientific evidence -- the IPCC's 2007 4th Assessment Report among them -- which says the data for dangerous, man-made global warming is unequivocal.

On current trajectories, according to an assessment by German academics released on Monday, Earth is headed for a sizzling increase of 3.5 degrees Celsius (6.3 degrees Fahrenheit) above pre-industrial times.

Previously published research says this scenario is a near-guarantee of disaster-inducing storms, droughts and floods across swathes of the globe.

But major actors in the climate drama -- China, India, the United States to name three -- have said during the talks that some key decisions should be postponed until after the IPCC's multi-volume 5th assessment report, due out in 2013-2014.

The IPCC produces every five to six years the definitive reference guide for policy makers on global warming and its impacts.

"The (2007) 4th assessment report has enough substance, which provides the basis for taking action," Pachauri told AFP in the interview on Wednesday.

"If the world accepts this scientific reality, then surely they should do something about it.

"Certainly, the next report might close a few gaps, make a few refinements. But to say that we will wait for the next report seems like escapism," he said.

Pachauri applauded South African President Jacob Zuma for underscoring in his keynote address the importance of chaining action on greenhouse-gas emissions "to the demands of science."

In a Special Report released in November, the IPCC warned that climate change was on track to, in effect, create weather on steroids, boosting the intensity or frequency of extreme events ranging from heatwaves to hurricanes to diluvian downpours.

Natarajan met top negotiators from the European Union, the United States and the BASIC (Brazil, South Africa and China) other nations.

Government negotiators and ministers have gathered to agree on the next steps for combating climate change. Developments over the past week, however, indicate deep divisions between developed and developing nations especially on the obligations to reduce carbon emissions.

Under the 1997 Kyoto Protocol, 37 developed countries have been placed under international legal obligations to reduce carbon emissions during a first commitment period, which expires next year.

Some countries like Japan and Canada are withdrawing from the treaty, citing it's ineffectiveness because it leaves out the bulk of carbon emission produced by China, India and the US.

The EU is willing to sign up for a second commitment period under the Kyoto Protocol if emerging economies also agree to take binding carbon emissions cuts in the future. The bloc wants to begin discussions on the treaty by next year.

India has said that it will consider a legally binding treaty post-2020 providing developed nations fulfill "fundamental imperatives" in areas of mitigation finance and technology as well as addressing concerns of equity, unilateral trade barriers and intellectual property rights. It also wants a mid-year scientific assessment of the situation.

Natarajan said that India understood the EU's keenness for all emerging economies to have cuts, especially against the backdrop of the financial crisis.

"But we reminded them that they have already undertaken these commitments," she said.

The negotiations for the past two weeks were also hit by speculation that the alliance of BASIC group was divided, especially after China declared its willingness to consider a legally binding treaty after 2020.

Natarajan dismissed any such divisions.

"I want to emphasise the unity BASIC and other developing countries have has shown here," she said.