Amsterdam, Netherlands ? The president-elect won’t be there, but an Obama buzz will crackle through the conference hall when negotiators gather Monday for a final push toward a sweeping new global warming treaty.

“America is back,” says Sen. John Kerry, underscoring that Barack Obama’s election signals a U.S. intent to regain a leadership role on climate change.

“After eight years of obstruction and delay and denial, the United States is going to rejoin the world community in tackling this global challenge,” said the Massachusetts Democrat, in line to become chairman of the Senate Foreign Relations Committee.

Delegates from nearly 190 countries gather for two weeks in Poznan, Poland, meeting for fourth time in the past year. Previous talks have witnessed bickering, clashes and compromise in what the top U.N. climate official calls the most difficult and complex international negotiation in history.

They have set a deadline of December 2009 to complete an accord on reducing worldwide emissions of greenhouse gases blamed for changing the Earth’s climate.

Delegates say Obama’s election promises to energize a process that until now has been burdened by a U.S. reluctance to endorse any international climate regime.

“In Poznan there will be a buzz — we can call it the American buzz,” said Jake Schmidt, of the Natural Resources Defense Council. “The U.S. is back in the conversation, and back with a leader that gets it.”

At the same time, a global financial crisis has struck just when governments must commit to spending hundreds of billions of dollars to fight climate change.

A report by the U.N. climate change secretariat estimates that at least $200 billion will be needed annually to cut carbon emissions 25 per cent below 2000 levels by 2030. Hundreds of billions more may be needed for poor countries to deal with such effects of global warming as rising seas, water scarcity and shifts in farming, it said.

Some 9,000 delegates, activists and researchers will attend the Poznan meeting, which ends with a two-day summit of U.N. Secretary General Ban Ki-moon, 150 environmental ministers, and Kerry and other U.S. congressmen who are instructed to report back to Obama.

It comes as new data suggests carbon emissions are increasing rather than declining, adding vigor to scientists’ warnings that higher average temperatures will lead to more extreme storms, droughts and floods. U.N. monitors said last this month that total emissions from more than 40 reporting countries grew by 2.3 percent between 2000 to 2006.

“The need for real progress has never been more urgent,” U.N. climate chief Yvo de Boer said in a video message to delegates.

The Poznan conference is the halfway mark in a two-year negotiation to replace the 1997 Kyoto Protocol, which obliged 37 industrial countries to slash carbon emissions below 1990 levels by an average 5 percent by 2012.

Washington refused to ratify the protocol. President George W. Bush argued it would hurt the U.S. economy while making no demands on emerging economic powers like China, which has surpassed the U.S. as the world’s biggest polluter.

A breakthrough came at last December’s talks when China and other developing countries agreed to share the burden of controlling emissions — though without accepting the same limits as the industrial countries, and only if they get help to switch to lower-carbon economies.

Conferences since then have explored ways of raising the huge sums required, of giving incentives to countries to curb deforestation, on setting new emissions targets for industrial countries and on transferring technologies to less developed countries.