A schoolboy rides his bicycle past a billboard of for UN climate change conference in Nusa Dua, Bali, Indonesia, 28 Nov. 2007

Twenty thousand delegates, observers, business leaders, and government ministers from 190 countries meet in Bali, Indonesia, from December 3-14. They are gathering to discuss life after the Kyoto Protocol, the U.N. treaty on climate change, which expires in 2012.

The Bali meeting will engage delegates in dozens of technical, scientific and financial discussions relating to the current climate change protocol. But they are also meeting to consider the building blocks and a timetable for crafting a new, post-Kyoto agreement.

Climate negotiator Harlan Watson expects to reach consensus for a 'Bali Roadmap'

Harlan Watson is a member of the United States delegation. He says negotiators must come to a consensus over a Bali Roadmap that will advance talks under the United Nations Framework on Climate Change and "develop a framework that includes all major economies."

Much attention will focus on what the United States both says and does on the climate change issue. The U.S. signed the original U.N. Framework and Convention on Climate Change but didn't ratify the subsequent treaty.

When the Bush Administration later withdrew from Kyoto altogether, they argued that the treaty would hurt the U.S. economy. The Administration also said the treaty failed to require industrial developing nations, such as China and India, to comply with binding curbs on emissions of climate-changing greenhouse gases.

Watson says any new framework must address greenhouse gas emissions "in a way that would be both environmentally effective and economic sustainable."

The United States favors voluntary commitments over binding ones to curb greenhouse gas emissions. Elliot Diringer, with the PEW Center on Global Climate Change, argues that voluntary action outside a global treaty by the world's largest polluter is not an effective course.

"What is essential here is developing a comprehensive agreement that does establish binding international commitments for all the major economies." Diringer says flexibility is a critical component since all nations approach the issues differently. "Some might have targets as you see under Kyoto now, but some might have other types of commitments, policy commitments for instance."

Diringer says this approach offers some of the flexibility that the Bush Administration has been calling for. "But the critical difference is that we think that all these different approaches need to be integrated into a package based on binding international commitments."

Diringer says countries are not going to put forward their best effort unless they can be confident that other countries are contributing their fair share. "That," he says, "is best assured through a set of multilateral commitments."

California governor Arnold Schwarzenegger says his state's action on California far exceeds that of the federal government

The Bali meeting is expected to draw large delegations from non-governmental and business groups, the United States Congress and many U.S. state officials. Celebrated climate change activists like former Vice President Al Gore, California governor Arnold Schwarzenegger and actor Leonardo DiCaprio are likely to propose environmental policies significantly different from those advanced by the White House. For example, activists are likely to support a law pending in the U.S. Congress that would put a cap on U.S. carbon emissions.

World Resources Institute's Jonathan Pershing says a U.S law that caps emissions will put the country in a better position to negotiate globally

Jonathan Pershing, with the World Resources Institute, says there is a good chance the legislation will pass. "It looks for a major reduction on the order of 70 percent in the [carbon] capped sectors by 2050. That is a huge number. That is the equivalent of the European level of emissions changes and targets and puts the U.S. in a very different place in a subsequent negotiation."

But observers say any post-Kyoto agreement must also include growing economies like China, which is quickly overtaking the United States as the world's largest polluter. Pershing says the good news is that China has begun to put sustainability on its economic agenda. "They've got a 20 percent renewable target which is more aggressive than anything except a handful of the most aggressive of U.S. states."

Negotiators hope to write a new treaty by 2009. Nations will then have three years to ratify it before the Kyoto Protocol expires in 2012. Pershing worries that 2009 may be too ambitious a timeline because the lead-up falls during a U.S. presidential campaign and the final year of the Bush administration.