Weary ministers were locked Thursday in marathon UN talks aimed at braking the juggernaut of climate change, facing decisions on deal-breaking rows as a deadline loomed just over 24 hours away.
After 11 days' wrangling, delegations grappled for a 195-nation pact to crimp climate-altering emissions from coal, oil and gas, sparing future generations from worsening drought, floods and storms, and island-engulfing seas.
As all-night talks returned to disputes that have festered for more than two decades, French President Francois Hollande stepped in, seeking to inject a sense of urgency.
"It is important in this last phase that we remind the negotiators why they are here," Hollande said in Paris.
"They are not there simply in the name of their countries... they are there to sort out the issue of the future of the planet."
French Foreign Minister and conference host Laurent Fabius said he planned to produce a new text, based on the overnight talks, and that it was still possible to forge the historic accord by Friday's scheduled close.
"I hope, I hope that tomorrow we will have finished," Fabius said.
Setting the tone for the late-night haggle, a host of nations from all sides of the disputes voiced entrenched positions.
Delegates said, though, that the mood was still positive, and the toxic ambience of past climate talks had so far been absent.
Developing nations insist the United States and other established economic powerhouses must shoulder the lion's share of responsibility as they have emitted most of the greenhouse gases since the Industrial Revolution.
Rich nations argue emerging giants must also do more. Developing countries now account for most of today's emissions and thus will stoke tomorrow's warming.
South African negotiator Alf Wills said there had been no progress in the "big political issues", but everyone was expecting to confront them in the final hours.
"Many options cross our red lines," Luxembourg negotiator Carole Dieschbourg, representing the European Union, told other delegates.
One of the battlegrounds is what cap on global warming to enshrine in the accord, set to take effect in 2020.
Many nations most vulnerable to climate change want to limit warming to no more than 1.5 degrees Celsius (2.5 degrees Fahrenheit) over pre-Industrial Revolution levels.
However several big polluters, such as the United States, China and India, prefer a ceiling of 2C, which would allow them to burn fossil fuels for a while longer.
Barbados's environment minister, Denis Lowe, representing a bloc of Caribbean nations among the most vulnerable to rising sea levels, told the late-night session 1.5C was non-negotiable.
"We will not sign off on an agreement that represents the certain extinction of our people," Lowe said.
One of the biggest potential deal-busters remains money.
Rich countries promised six years ago in Copenhagen to muster $100 billion (92 billion euros) a year from 2020 to help developing nations make the costly shift to clean energy, and to cope with the impact of global warming.
But how the pledged funds will be raised still remains unclear -- and developing countries are pushing for a promise to ramp up the aid in future.
Another trigger issue is how to compensate developing nations that will be worst hit by climate change yet are least to blame for it, as they have emitted the least greenhouse gas.
Most nations submitted to the UN before Paris their voluntary plans to curb greenhouse gas emissions from 2020, a process that was widely hailed as an important 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.
Another battle front is over when and how often to review national plans so that they can be "scaled up" with pledges for deeper emissions cuts.
But some developing nations insist they should not be pressured into deeper reductions.
Despite the hurdles, negotiators and long-time observers said a deal could be reached in Paris.
"There is a lot of hard work, long hours to go," Elina Bardram, head of the European Union's climate delegation, said on Thursday.
"But I remain very confident that political determination will also be projected into the negotiation rooms and that we will end with a very solid... agreement."
Green groups are worried the outcome may end up so compromised that it will not do nearly enough to tame global warming.
Previous UN climate conferences have extended well past their scheduled finishing times, meaning talks could go into the weekend.
But Fabius has said he is determined for the Paris talks, which began on November 30 with a record-breaking summit of 150 world leaders, to end on Friday.