Washington  - Former US vice president Al Gore on Wednesday urged a stronger global effort to combat climate change as governments gear up for a tough year of negotiations on a new global treaty to lower greenhouse-gas emissions.

Gore, who shared the 2007 Nobel Peace Prize for his efforts to raise awareness of global warming, said he rejected as a "false choice" the debate between tackling climate change and averting a recession that has taken hold in the United States and many other economies.

"The solutions to the climate crisis are the very same solutions that will address our economic and national security crises, as well," Gore said in testimony before the US Senate's Foreign Relations Committee.

At issue was an "urgent and unprecedented threat to the existence of our civilization" as a warming planet threatens to unleash stronger storms, more droughts, rising sea levels and other dangers.

President Barack Obama signalled an immediate shift in US climate policy at the start of his administration, promising to cut greenhouse-gas emissions 80 per cent by
2050.

Earlier this week he named Todd Stern as a special envoy for climate change to lead negotiations on a new global treaty. He also signed executive orders allowing US states like California to enact tougher vehicle emissions rules - the first step towards reversing a Bush administration block on such state action.

Governments have resolved to agree by the end of this year on an enhanced climate deal that would place further restrictions on countries' greenhouse-gas emissions. The Kyoto Protocol, the world's first attempt at setting international targets, expires in 2012. It was never adopted by the US.

Gore said it was critical that a new deal be reached by the end of this year. US leadership would be key to getting other countries on board a new treaty, which must include commitments from industrial and developing economies and will be thrashed out at a climate summit in Copenhagen in December.

"A fair, effective and balanced treaty will put in place the global architecture that will place the world, at long last and in the nick of time, on a path toward solving the climate crisis," Gore told the committee.

But Gore said the United States would have to enact its own domestic limits on emissions by the end of this year in order to "regain its credibility" ahead of the Copenhagen talks.

Obama has called for a cap-and-trade programme that would force heavily polluting companies to pay for their emissions. But the plan faces some opposition from Congress - especially in the midst of a serious recession - and passage by the end of this year is in doubt. dpa