French Foreign Minister Laurent Fabius presented the revised text just before negotiators headed into closed overnight meetings. While the final agreement is due on Friday, some experts speculated talks will bleed into the weekend.
"It does look like there's some work to be done," said Rachel Cleetus, the lead economist and climate policy manager for the Union of Concerned Scientist's Climate and Energy Program.
"But I think there's a lot of hope and optimism that Paris will deliver a positive outcome," she added. "But we won't know until we see that final agreement."
At 27 pages, the revised draft trimmed the number brackets -- which indicate contested text -- from 1,622 in the pre-COP text to 48. Sticking points include how to finance mitigation and adaptation in developing countries, what level of commitments should be expected for wealthy versus poor nations, and the tracking of progress toward those commitments.
Also remaining is the broader question of how ambitious the agreement will be. The language of the current draft states the need to hold "the increase in the global average temperature to well below 2 °C above preindustrial levels" and to pursue "efforts to limit the temperature increase to 1.5 °C."
Forming the backbone of the climate pact are emissions-reduction pledges, known as Intended Nationally Determined Contributions, which were submitted by participating countries ahead of the conference. But as HuffPost reported, those promises fall well short of what scientists say is necessary to stave off catastrophic climate change, including the devastating floods, droughts, storms and food shortages it could continue to bring.
"There is a clear understanding that INDCs are not enough," said Cleetus. "But a strong signal from Paris that we can build ambition over time could do the trick."
That ambition, Cleetus said, needs to reflect mitigation as well as adaptation -- both driven by "adequate finance." And how quickly this needs to happen also remains up for debate. The latest text uses the phrase, "as soon as possible" as the loose deadline for reaching "the peaking of greenhouse gas emissions." It also recommends that countries "undertake rapid reductions thereafter towards reaching greenhouse gas emissions neutrality in the second half of the century." Some climate experts prefer a more concrete, earlier date.
Critical in all this is the "recognition that whatever temperature threshold, 1.5-degrees Celsius or 2-degrees Celsius, will result in a fair amount of climate impacts," said Cleetus. "We definitely need to help countries cope."
In 2009, developed countries pledged to send $100 billion annually to developing countries to support their climate change initiatives. Yet details remain unclear. An announcement by Secretary of State John Kerry on Wednesday that the U.S. will commit more than $800 million a year to financing climate adaptation in developing countries was a "very positive sign," Cleetus said.
Not everyone is hopeful. "Unfortunately, I expect the text to not meet the necessary ambition and clarity on climate finance," Guido Schmidt-Traub, executive director of the U.S. Sustainable Development Solutions Network, told HuffPost in an email.
Still, experts do seem to agree that spirits are far higher in Paris than at previous climate meetings, such as in Copenhagen in 2009, which was plagued by the same failed attempts and artificial promises as previous summits.
"The difference in Paris," said Cleetus, is that "parties came here to make an agreement. The question now is just how ambitious that agreement is going to be."
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