Even if a deal is reached at the UN climate change talks in Copenhagen next week it will only be the first step towards the far more radical cuts that are needed in global carbon emissions, Al Gore, the former US Vice-President, told The Times last night.

Mr Gore said that to avoid the worst ravages of climate change world leaders would have to come together again to set more drastic reductions than those now planned.

“Even a final treaty will have to set the stage for other tougher reductions at a later date,” he said. “We have already overshot the safe levels of CO2 in the atmosphere.”