The world is speeding towards a climate catastrophe, UN chief Ban Ki-moon warned yesterday, urging rapid progress in talks to cut emissions and tackle global warming.

"Our foot is stuck on the accelerator and we are heading towards an abyss," the UN secretary general said in a speech to the World Climate Conference.

Mr Ban, who this week visited the Arctic to witness first hand the changes wrought by global warming, warned that many of the "more distant scenarios" predicted by scientists were "happening now."

"Scientists have been accused for years of scaremongering. But the real scaremongers are those who say we cannot afford climate action - that it will hold back economic growth," he said.

"They are wrong. Climate change could spell widespread disaster," Mr Ban warned.

The UN leader pinned his hopes of a breakthrough on a summit of world leaders in New York on September 22 to discuss climate change.

Talks on an agreement to extend the Kyoto protocol on emissions cuts in time for December's Copenhagen conference had been too limited and slow, he said.

"We have 15 negotiating days left until Copenhagen. We cannot afford limited progress. We need rapid progress," he added, criticising "inertia" towards climate change.

"In New York, (I) expect candid and constructive discussions. I expect serious bridge building. I expect strong outcomes," Mr Ban told delegates and ministers from some 150 countries at the meeting in Geneva. The UN chief warned that the price of failure in Copenhagen would be high "not just for future generations, but for this generation."

Mr Ban later reiterated that a pledge by the G8 leading industrialised countries this summer for a long-term 80 per cent cut in emissions by 2050 was not sufficient.

"I continue to believe that they should have a mid-term target, I'm going to continue on that with the G8 and G20 (leading economies)," he told journalists.

Visibly sobered by his Arctic visit, Mr Ban warned that rising sea levels, partly generated by melting ice, would threaten major cities and potentially up to 130 million people.