A giant birthday cake was unveiled on the sidelines of the talks in Bali to commemorate December 11, 1997 when the world's most ambitious environment treaty was born in the eponymous Japanese city.

Two parties followed in the evening, one hosted by Japanese green groups and the other by the UN Framework Convention on Climate Change (UNFCCC).

The Kyoto Protocol took effect on February 16, 2005 after gruelling negotiations to complete its rulebook on curbing greenhouse-gas emissions.

But, in its present form, it will not do enough to stem the surge in pollution, which scientists say is badly damaging the Earth's climate system.

Worse droughts and floods, rising sea levels and more violent storms lie just decades away, they warn.

The conference of 190 countries is seeking a "Bali Roadmap" to set the parameters for further negotiations leading to a new accord to accelerate cuts in greenhouse-gas emissions after 2012, when the protocol's current pledges expire.

European Environment Commissioner Stavros Dimas said just three days remained for ensuring a new pact "is sufficiently ambitious to tackle the climate challenge we face."

"I believe that this conference is on track to deliver good results, but the next three days will be decisive and I have no doubt that there will be some difficult discussions," he said.

Talks on the Bali Roadmap are struggling on key questions on how extensive the post-2012 negotiation mandate should be and whether these parlays should be set a two-year deadline.

One of the rows is over a previous commitment made by Kyoto's industrialised countries, which said they had an "ambition" to reduce their own carbon emissions by between 25 and 40 percent by 2020 compared with 1990 levels.

The 25-40 percent figure holds major resonance, as it chimes with an estimate by the UN's Nobel-winning scientific panel for limiting warming to around two degrees Celsius (3.6 degrees Fahrenheit) over pre-industrial times.

Attempts by the European Union (EU) to enshrine this tentative commitment in the Bali text have come under attack from group that includes the United States, Japan and Canada.

They argue that such figures would prejudge the negotiations for the post-2012 accord.

"It's not enough to say we want to continue to negotiate. There must be named targets... otherwise we'll be afraid to go home," said German Environment Minister Sigmar Gabriel.

But green activists warned against changes that would turn the much-vaunted roadmap into a directionless fudge.

"Ministers cannot leave Bali without an ambitious mandate. People won't buy it," said WWF's Hans Verolme.

UNFCCC Executive Director Yvo de Boer, however, stressed that the figures of 25-40 percent had never been cemented as a reduction "target" for rich countries, and was more of a guideline.

These and other thorny details are expected to be shunted over to environment ministers, whose meeting from Wednesday to Friday will end the conference.

Late Monday, the talks notched up their first significant success with a decision on how to administer a fund to bolster the defences of poor countries that lack the money, technology and skills to cope with climate change.

It will be financed by a levy of two percent on transactions under the Clean Development Mechanism (CDM), a piece of Kyoto machinery by which rich countries get carbon credits. They can offset these credits against their emissions targets, provided they invest in clean-energy projects in poor countries.

Green activists and development groups lashed the United States for failing to support the Adaptation Fund, given estimates that poor countries will need as much as 86 billion dollars a year to cope with the ravages of climate change.

The Bali talks are taking place against a backdrop of dark scientific warnings about climate change and growing public and political awareness.

The issue's profile has grow rapidly this year, capped by the awarding of the Nobel Peace Prize on Monday to climate campaigner Al Gore and the UN's paramount scientific body on global warming, the Intergovernmental Panel on Climate Change (IPCC).

One consequence of climate change's rise has been recognition that it is now spilling over into many other domains. For the first time, finance ministers staged their first meeting in parallel with the UNFCCC meeting, preceded by a two-day meeting at the weekend of trade ministers.