World leaders in Copenhagen were expected to talk late into the night (this morning NZT) to try to shift the deadlock that has emerged between industrialised countries, the big developing countries and poor nations.
But it is looking increasingly likely that whatever is announced, there will be much work left to be continued at renewed talks in Mexico next year.
Al Gore has called on leaders to pull forward the next stage of talks to the middle of 2010 rather than waiting until the end of the year.
After a disappointing few days there was renewed hope going into the final meeting that leaders might be able to strike a deal.
US Secretary of State Hillary Clinton's offer of a $100 billion a year fund from 2020 to provide long-term help for poor countries to adapt to the effects of climate change has been hailed as a "game-changer" following days of hard-ball tactics and a general breakdown of trust.
Emphasising the high stakes involved, a leaked UN draft report showed that the emission cuts tabled at Copenhagen so far would lead to world warming by an estimated 3C - worse than the 2C many countries are aiming for.
Prime Minister John Key remains hopeful of a deal at Copenhagen but thinks if progress is to be made, ambitions need to be lowered.
Addressing the conference yesterday, Mr Key called on the big economies to show leadership, saying New Zealand was acutely aware of the danger climate change posed for its Pacific Island neighbours and big powers needed to consider the plight of vulnerable nations.
"Progress will require commitment, compromise and cash.
"But now is the time for us all to face the reality: that of all the options on the table at Copenhagen, failure is the one we can all least afford."
New Zealand was committed to playing its part, Mr Key said, citing its emissions trading scheme.
He pushed New Zealand concerns around forests and agricultural emissions and argued against constraints on the carbon market.
"The wrong rules could significantly undermine New Zealand's future as a food producer to the world for no environmental gain."
Speaking to Radio New Zealand yesterday, Mr Key said it was too soon to give up on a deal.
"We want to see some progress being made. I think in one sense maybe even if we start from a lower base, just getting everyone on the same page and starting to move forward is potentially one of the most important things that we can do."
Meanwhile a spokesman for Mr Key, Kevin Taylor, questioned reports that the Prime Minister was bumped from a BBC climate change debate because he told the broadcaster he might not not be able to attend.
Mr Taylor said the PM told the BBC when he was first approached that he was not going to Copenhagen and referred the producers to Environment Minister Nick Smith. But when Mr Key announced he would attend Copenhagen he spoke to the BBC again, he said.
"As late as last week I was talking to [their producer] and it was all go," said Mr Taylor.
The PM then heard rumours that Australian Prime Minister Kevin Rudd might have replaced him and learned the truth only when he arrived in London en route to the climate talks, he said.
A representative of the BBC's partner in the broadcast, the Danish Broadcasting Corporation, said this week that it was the BBC's decision who would take part, but hinted that he did not think Mr Key's appearance was ever confirmed by the broadcasters.
- ADDITIONAL REPORTING: NZPA