Climate change is taking place even faster than the worst predictions made by the UN's Nobel prize-winning panel on climate change, Al Gore said this morning.

The former US vice-president and winner of the 2007 Nobel Peace Prize said that there were forecasts that the North Pole ice cap could disappear during summer months within five years.

Mr Gore, who shared the Nobel with the panel for his own efforts to counter climate change, said: "We could take the whole session talking just about the new scientific evidence of the last few weeks and months.

"The climate crisis is significantly worse and unfolding more rapidly than those on the pessimistic side of the IPCC [International Panel on Climate Change] projections had warned us."

Mr Gore added that any of the main Democrat or Republican candidates would make a better US President than his own nemesis, George Bush, who defeated him in the controversial presidential race in 2000, in the fight against global warming.

He said that John McCain, the Republican front-runner, had a "reasonable position that did not go far enough", while he believed that the evangelical background of other Republican candidates meant that they would be driven by moral reasons to do more on climate change.

But for the maker of An Inconvenient Truth, the film that gave warning of the emergency of global warning, only a compulsory, global carbon trading system could really tackle global warming.

He argued that seemingly expensive renewable energy sources were actually comparable in price with fossil fuels when carbon costs were taken into account, "when coal is adjusted to reflect its true price, the cost of capturing carbon from burning coal".

Sharing the platform, Bono, the U2 frontman, accused the world's richest countries of reneging on promises made in 2005 for a $50 billion rise in aid by 2010. Overall, aid to Africa fell in real terms in 2006.

The musician said: "The G-8 are not making good on their commitments. This is a scandal. It makes the kind of dialogue that social movements have been having with governments look preposterous."

But, ever keen to share his personal contacts with world leaders, he said he had fresh verbal pledges from the leaders of Germany and France.

"[Chancellor] Angela Merkel has promised to meet her commitment and that is courageous" given Germany's other spending, he said.

President Sarkozy of France told him last week that he, too, would try to keep his country's promise to the world's poorest people.

Bono said: "Sarkozy said: 'It is very hard for me, I made a promise to the French people to make their lives better, but I commit to you — we will get to work and keep our promise'."

There had been some successes. "There are now two million Africans on retroviral drugs and that is pretty astonishing," Bono said.

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