Speaking to CNBC Nicholas Stern, chair of the Grantham Research Institute on Climate Change and the Environment, said that there was a "great mood" to resolve remaining issues.
"If you measure in terms of brackets in (the) text – brackets is unagreed text – I think in the two days that we had up to last night when the latest version came down, we went from 350 brackets down to about 50," he said. "So we're moving towards agreement here."
"There is a difference of course between what developed countries do and what developing countries do and there are discussions still, not quite finalized, on flows of finance, and those are important too," he added.
According to Reuters, delegates said there was a split in relation to who should pay for developing nations to transition to low carbon economies, as well as money to mitigate the impact of global warming across the planet.
Going into the last 24 to 36 hours, Stern said that, overall, he thought parties were close to an agreement.
"As (Baseball legend) Yogi Berra has said, 'it ain't over til it's over' but we have to be very optimistic but (also) very careful, because in a state of affairs where you look for consensus, you do get last minute hold outs."
Stern added that the text being worked on was "really quite strong" and "charting a course."
"It's saying the transition to (a) low carbon economy is where we're going, it's very attractive, it's the growth story," he added.