BANGKOK • Time is running out to save the Paris Agreement, United Nations climate experts warned at a key Bangkok meeting, as rich nations were accused of shirking their responsibility for environmental damage.

The six-day UN conference opened yesterday with an urgent plea from delegates to finalise a "rule book" governing the Paris Agreement, the most ambitious global pact yet to address the impact of climate change.

The rule book will have guidelines for the treaty's 197 signatories on how to provide support to developing countries worst affected, and manage the impact of climate change.

If nations cannot reach an agreement by a December summit in Poland - known as COP24 - the Paris Agreement, carved out in 2015, will be at risk.

"The credibility of the process... is at stake," Mr Michal Kurtyka, president-designate of COP24, said at the opening of yesterday's meeting. "We are not moving as swiftly as we can," he added. "We need concrete propositions and solutions now."

Money is at the heart of issue. The Paris pact has promised US$100 billion (S$137 billion) annually from 2020 to poor nations coping with floods, heatwaves, rising sea levels and super storms made worse by climate change.

Developing countries favour grants from public sources and demand visibility on how donor nations intend to scale up this amount.

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Rich countries want more private capital in the mix and prefer projects with profit potential.

Pressure is mounting on developed nations to take on more long-term financial responsibility given that their progress has exacerbated climate change.

As the impact gets worse, "the poorest and most vulnerable, who have contributed almost nothing to the problem, suffer more", Ms Patricia Espinosa of UN Climate Change said in a statement.

The Paris Agreement promises to cap the rise in global temperatures at "well below" 2 deg C. But current pledges by countries would allow it to climb by more than 3 deg C.

The talks have also been marked by high-profile exits. President Donald Trump announced last year that the United States was leaving the agreement, and has refused to honour a US$2 billion pledge.

AGENCE FRANCE-PRESSE