The two weeks of talks come amid increasingly dire warnings about the warming of the planet. In mid-November, the Nobel Prize-winning scientists on the U.N. Intergovernmental Panel on Climate Change released a report stating that greenhouse gas emissions must begin to decline by 2015 and be cut at least in half by 2050 to avert global disasters like drought, rising seas and mass species extinctions.
And last week, the U.N. Development Program released a report warning that rising temperatures, if not held in check, will cause large-scale humanitarian disasters: displacing millions of people through flooding and threatening others with starvation and lack of drinking water.
Against this backdrop, the Bali conference's aim is to begin negotiations for an emissions-reduction treaty to succeed the Kyoto Protocol, which will expire in 2012. The protocol, which 175 nations agreed to in 1997, requires 36 industrialized countries to reduce greenhouse gas emissions by an average of 5 percent below 1990 levels by 2010.
The United States and Australia, however, never agreed to the treaty.
The U.N. hopes to begin a process that will bring in both the United States and developing countries--which are not required to make any emissions cuts under Kyoto. The goal is to complete the negotiations by 2009 to give countries time to ratify and implement the treaty by 2012.
Some U.N. leaders were cautiously optimistic. Rajendra K. Pachauri, chairman of the IPCC, told reporters he expects "a likely agreement on a roadmap" to come out of Bali, according to Agence France-Presse.
"There is an unprecedented awareness among the public and leaders now. This augurs some seriousness towards the discussions that take place and the negotiation of post-2012 commitments," he said.
Many experts, however, believe that that a new global agreement by 2009 will be difficult to achieve.
"The goal of a deal in 2009 is extraordinarily ambitious," Elliot Diringer, of the Pew Center on Global Climate Change, told Reuters.
There are many sticking points. President Bush, in outlining his reasons for opposing the Kyoto treaty , argued that binding agreements to cap emissions would be too harmful to the U.S. economy, and that reductions should also be required of developing but quickly industrializing countries such as China and India.
In recent days, the administration has reiterated its position that it doesn't plan to make any commitments to specific emissions reductions in Bali.
"We would like to see a consensus on the launch of negotiations," Under Secretary of State Paula Dobiansky, who will head the U.S. delegation to Bali, told the Associated Press. "We want a framework that is global in nature so that it can be environmentally effective and economically sustainable."
But within the United States, there is some building political pressure to act. Some in Congress recently pushed for mandatory emissions-capping legislation. Sen. Barbara Boxer, D-Calif., has scheduled a vote for this week that would require reducing emissions 70 percent by mid-century.
And in Australia, Prime Minister-elect Kevin Rudd said last week that he plans to submit the Kyoto Protocol to the Australian Parliament to ratify. That would make the U.S. the only industrialized nation outside the Kyoto Protocol.
A Chinese official, meanwhile, recently told Reuters that China would be reluctant to agree to binding carbon reduction commitments without the promise of financial aid from industrialized countries.
"Only when I know what technology I have can I calculate how much I can reduce emissions; only when I have funding assurances," Gao Guangsheng, director general of climate change at the National Development and Reform Commission, told Reuters.
Given these limitations, "I think the best plausible outcome from Bali is a process that isn't explicitly about commitments at the outset," said the Pew Center's Elliot Diringer, "but could evolve into a negotiation about commitments."
Many other topics will be on the table in Bali in addition to emissions-cut commitments. Delegates may discuss setting aside money to help countries adapt to some inevitable effects of climate change and compensating some developing countries for reducing deforestation, which creates more greenhouse gasses.