NUSA DUA, Indonesia -- A historic agreement reached here Saturday afternoon paves the way for a new global warming treaty that for the first time will include binding emission reductions from major economies such as the United States and also commitments from developing nations like China and India.

The "Bali Road Map" approved after two tense weeks of talks requires about 180 countries to reach agreement by 2009 on a treaty pressing for "deep cuts" in emissions from all governments. There is no specific target named in the United Nations document, but it nonetheless appeared to satisfy most with a reference to key findings from the Nobel Peace Prize-winning Intergovernmental Panel on Climate Change.

Also in the text is a first-ever program to help halt destruction of tropical rainforests, a source of 20 percent of heat-trapping emissions every year, as well as a much more sweeping set of goals for helping the poorest countries adapt to inevitable climate change.

"This is a real breakthrough, a real opportunity for the international community to successfully fight climate change," U.N. climate chief Yvo de Boer told reporters.

But it almost didn't happen.

Closed-door negotiations dragged into early Saturday morning without consensus, forcing delegates to return for one final session a few hours later. Many participants were working on little or no sleep.

Frustration poured out when the talks resumed as China and India openly criticized the U.N. conference's organizers for scheduling two sessions at the same time. De Boer, trying to apologize for the miscommunication, left the room in tears.

The drama continued when the United States raised objections after a last-minute change expanded the role it would play in helping poor nations cut their emissions by sharing low- and zero-carbon energy technologies. The U.S. objections prompted a chorus of boos and hisses -- and a series of harsh speeches.

"There's an old saying, 'If you're not willing to lead, get out of the way.' And I would ask the United States, we've asked for your leadership, we seek your leadership, but if for some reason, you're not willing to lead, leave it to the rest of us," declared Papua New Guinea delegate Kevin Conrad. "Please get out of the way."

The entire U.N. agreement rested in the balance, and U.S. Undersecretary of State Paula Dobrianky blinked.

"We have come a long way here," she said about 30 minutes after first raising her complaint. "In this, the United States is very committed to this effort and just wants to really ensure we all will act together. With that, Mr. Chairman, let me say to you we will go forward and join consensus in this today."

A standing ovation followed as delegates realized they were one big step closer to adopting the Bali agreement.

White House Council on Environmental Quality Chairman Jim Connaughton downplayed the dispute. "We understand many delegations were concerned," he said in an interview. "But they wanted to be sure that we were satisfied as well."

Tear down the 'Berlin Wall'

Perhaps the biggest shift to emerge from the U.N. conference came from the major developing countries that are now on record accepting "nationally appropriate mitigation actions" that must be "measurable, reportable and verifiable."

It is not a cap on their absolute emissions. But it is a major reversal on a previous 12-year-old agreement -- known in U.N. parlance as the 'Berlin Mandate' -- that had excluded China, India and other developing countries from taking significant steps toward reducing emissions.