UN climate change officials have gathered in Bali for what are expected to be contentious talks on a replacement to the Kyoto Protocol.
Officials told delegates from about 190 countries that the eyes of the world would be on the 12-day meeting, and that time was running out in the fight against global warming.
"We're already seeing many of the impacts of climate change," Yvo de Boer, head of the UN climate change secretariat, said.
"We are on a very dangerous path."
The conference, which begins on December 3, will attempt to kickstart talks over the Kyoto Protocol which is due to expire in 2012.
A new agreement must be concluded within two years to give countries time to ratify it and ensure an uninterrupted transition.
"There is a very clear signal from the scientific community that we need to act on this issue," said de Boer.
"We have to turn the trend of global emissions in the next 10 to 15 years."
Global warming
The Kyoto pact, signed a decade ago, required industrial nations to reduce carbon dioxide and other heat-trapping gasses emitted by power plants and other industrial, agricultural and transportation sources.
Only 36 nations signed up to the pact, with the US and China, the world's biggest greenhouse gas emitters, remaining outside.
But prospects for a global deal were boosted recently when Kevin Rudd, whose party swept to power in Australia one week ago, immediately put signing the Kyoto pact at the top of his international agenda.
Australia had previously refused to sign the agreement.
George Bush, the US president who opposed Kyoto as a threat to US economic growth, also recently suggested the US would take part beyond 2012.
"We'd like to see consensus on the launch of negotiations. We want to see a Bali roadmap," said Paula Dobriansky, US undersecretary of state for democracy and global affairs.
"We will go to Bali with openness, flexibility."
China factor
Senior Beijing officials were reported by the Reuters news agency last week as saying that China would do more to strengthen its existing domestic targets to improve energy efficiency and curb greenhouse gas emissions, if other world powers shared relevant technologies.
"If help is forthcoming, if international cooperation is as it should be ... we will definitely do more," Yu Qingtai, a climate change negotiator, was quoted as saying.
Delegates at the Bali conference will also consider whether cuts in carbon emissions should be mandatory or voluntary, how to reduce deforestation, and ways to help poor countries expected to be hardest hit by worsening droughts, floods and violent storms.