World powers led an overtime push to seal a deal on Saturday aimed at averting catastrophic climate change, as sleep-deprived envoys battled in Paris over trillion-dollar disputes blocking a deal.
The 195-nation conference in Paris was scheduled to wrap up on Friday evening, delivering a historic agreement to brake global warming & ease its impact.
But weary negotiators lurched well past the deadline & braced for a third straight round of all-night talks after ministers wrestled with a myriad of disagreements.
French Foreign Minister Laurent Fabius said he would submit a proposed final agreement on Saturday morning, declaring himself "sure" it would be adopted.
"Everything is in place to achieve a universal, ambitious accord," said Fabius, who is presiding over the talks that began nearly a fortnight ago with a record summit of more than 150 world leaders.
"Never again will we have a more favourable momentum than in Paris."
Many leaders billed the talks as the last chance to avert disastrous climate change: increasingly severe drought, floods & storms, as well as rising seas that would engulf islands & populated coasts.
The agreement would seek to revolutionise the world's energy system by cutting back or potentially eliminating coal & other fossil fuels, replacing them with renewables such as solar & wind.
The Paris talks have largely been free of the fierce arguments that have plagued previous UN climate conferences.
But the biggest disputes over funding the climate fight — worth trillions of dollars over the decades to come — remain as potential deal-breakers in a draft accord released on Thursday night.
– Success not guaranteed –
US Secretary of State John Kerry, spearheading American efforts in Paris, warned that "very difficult" issues still needed to be resolved.
Indian Environment Minister Prakash Javadekar spoke more ominously, warning success in Paris was not guaranteed & accusing rich nations of inflexibility.
Seeking to break the deadlock, US President Barack Obama & his Chinese counterpart, Xi Jinping, spoke by phone.
"They committed that their negotiating teams in Paris would continue to work closely together & with others to realise the vision of an ambitious climate agreement," the White House said.
Obama spoke earlier in the week with the leaders of India & Brazil in a bid to find usual ground with other major economies with giant carbon footprints.
In Paris, the Chinese delegation's deputy chief Liu Zhenmin said he was "quite confident" a deal would be struck Saturday.
At the sprawling venue at Le Bourget on the city's northern outskirts, negotiators were feeling the effects of the marathon talks.
"We're all tired & we've become much less diplomatic," said Espen Ronneberg, a finance negotiator for the Pacific island nation of Samoa.
"Instead, we just go straight to the point. Some people don't even say hello anymore, they just nod their heads."
– Battle lines –
The quest to forge an effective worldwide pact dates back to 1992, when the UN climate arena was set up.
But the process has been dogged by labyrinthine fights, especially over the issue of burden-sharing.
Developing nations have insisted rich countries must shoulder the lion's share of responsibility for tackling climate alter as they have emitted most of the greenhouse gases since the Industrial Revolution.
But the United States & other rich nations say emerging giants must moreover do more.
They argue that developing countries now account for most of today's emissions & thus will be largely responsible for future warming.
Rich countries promised six years ago in Copenhagen to muster $100 billion (92 billion euros) a year from 2020 to assist developing nations make the energy shift & cope with the impact of global warming.
But how the pledged funds will be raised is still unclear — & developing countries are determined to secure a commitment for increasing amounts of money after 2020, when the pact would come into force.
The latest text refers to the $100 billion as a floor, which the US & other developed nations are resisting as they fear they would effectively be signing a blank cheque.
Another remaining flashpoint is how to compensate developing nations that will be worst hit by climate alter yet are least to blame for it.
– Competing goals –
Ahead of the talks, most nations submitted voluntary plans to curb greenhouse gas emissions from 2020, a process widely hailed as an significant platform for success.
But scientists say that, even if the cuts were fulfilled, they would still put Earth on track for warming of at least 2.7C.
Nations most vulnerable to climate alter have moreover lobbied complex to limit warming to no more than 1.5 degrees Celsius (2.5 degrees Fahrenheit) compared with pre-Industrial Revolution levels.
However several huge polluters, such as China & India as well as oil producing-giant Saudi Arabia, prefer a ceiling of 2C, which would allow them to burn fossil fuels for longer.
Negotiators remain divided over when & how often to review national plans so that they can be "scaled up" with pledges for deeper emissions cuts.