Diplomats have lamented the "snail's pace" of this week's haggle in Bonn, accusing one another of rehashing well-rehearsed positions and holding up the real work of line-by-line text bartering.
Today will be the sixth-to-last negotiating day, with five more to follow in October, before the highly-anticipated November 30-December 11 UN conference opens in Paris in the presence of heads of state.
Delegates said the Bonn preparatory round, which opened Monday, made piecemeal progress on some of the detailed discussions, but the overall objective of a universal deal remained far off.
"The time for talking about concepts and general chit chat is over," said Gurdial Singh Nijar, a Malaysian negotiator and spokesman for the Like Minded Developing Nations bloc, which includes China, India, and many African, South American, Middle Eastern and Asian countries.
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"Only through direct, inclusive and interactive negotiations will parties be able to narrow down differences, find convergence and ultimately achieve consensus," he said in a statement.
The Paris agreement is meant to slow the march of dangerous global warming by slashing climate-altering greenhouse gas emissions from mankind's unbridled burning of fossil fuels.
The overarching goal is to limit average warming to two degrees Celsius over pre-Industrial Revolution levels.
Fundamental divisions remain over how to share out carbon-emissions cuts between rich nations, which have polluted for longer, and emerging giants such as China and India powering fast-growing economies and populations.
"Everyone says: 'we're not making progress' but no one says: 'I'll withdraw this or that proposal'. Nobody wants to give up anything essential.