A growing sense of urgency is pushing world leaders to agree a new treaty to fight climate change but the U.S. presidential election might still foil hopes of a deal by the end of 2009, experts told a Reuters summit.

Many countries, including the United States and its main industrial allies in the Group of Eight, want a climate pact agreed by the end of 2009 to help slow warming that may bring more floods, droughts, heatwaves and rising seas.

"There is a sense of urgency," Yvo de Boer, head of the U.N. Climate Change Secretariat, said of the mood among world leaders facing with mounting evidence of global warming. But he said not all were ready to sign up to a 2009 deadline.

Investors want to know long-term rules as soon as possible to decide whether there will be penalties on greenhouse gas emissions from coal-fired power plants, for instance, or tax breaks for windmills.

The United Nations wants a deal in place by the end of 2009 to give three years for ratification by national parliaments before the expiry of the Kyoto Protocol, the main U.N. plan for fighting global warming until 2012.

Many experts told a Reuters Environment Summit this week that 2009 was possible but talks would slip because of factors including the U.S. presidential election in 2008 and the complexity of dividing curbs between rich and poor.

"There's every reason to believe in the possibility" of a deal by the end of 2009, said Achim Steiner, head of the U.N. Environment Program.

"A lot will hinge on essentially what happens in the United States, and there we have every reason to believe that the position of he United States over the next few years will not be the same as it was," he said.

President George W. Bush decided in 2001 against implementing the U.N.'s Kyoto Protocol in a break with most of his industrial allies except Australia.

SPILL OVER

"I absolutely do," said Charlie Crist, the Republican governor of Florida, when asked if he believed in a world deal by the end of 2009. "I'm an optimist". A new president will need time to work out policies after taking over in January 2009.

Many U.S. presidential candidates argue that the United States needs to take a stronger role in U.N. climate talks. But many other nations are reluctant to make big promises until Washington's policies are clear.

"My feeling is that we will at least be pretty close to an agreement" on a new global deal to replace Kyoto by the end of 2009, said Rajendra Pachauri, head of the U.N. Climate Panel. "It may spill over by a few months."

Kyoto binds 36 rich nations to cap emissions of greenhouse gases until 2012 and a new global deal would seek to engage outsiders such as the United States and developing countries such as China, India and Brazil.

"We need to feel the urgency that the planet demands of us. We are the planet's conscience," Brazilian Environment Minister Marina Silva said. "If it depended on me, on Brazil and other leaders in various parts of the world, I think we will" have an accord by end 2009.

De Boer said that a meeting of U.N. environment ministers in December in Bali should set a 2009 deadline. "Otherwise conceivably the process could go on indefinitely," he said.

Governments took eight years to ratify Kyoto, from 1997 to 2005.

Bush said Kyoto would cost too much and wrongly omitted binding targets for developing nations. In a shift, he now wants major emitters to agree long-term targets for curbs by the end of 2008 to bolster chances of a U.N. pact in 2009.

And Australia might shift course if an election due within weeks brings the opposition Labor Party government to power. Labor is committed to ratifying Kyoto.

Climate change "is the ultimate challenge to the international community, and to that extent it is a challenge we can't fail," said Peter Garrett, Labor's environment spokesman.

Australia Florida George W. Bush Charlie crist