Nations are taking firm positions with little room for stepping back. But there is always the hope of a magical solution. Lowering expectations is step one.
One of the toughest disputes is over which countries should commit to reducing their levels of greenhouse gases.
The industrialised nations say that big polluters in the developing world, notably China and India, must be included in any treaty commitments.
The head of the US delegation here, Jonathan Pershing, said that having those two countries included was "absolutely part of the deal".
"We see success in Copenhagen as in no small measure a function of what all these major players do," he told BBC News. "Ourselves, Europe, China, India, Japan - it has to be the major emitters. If we think of a group of about 15 countries, they comprise on the order of 75% of global emissions.
"We can't solve this without them; you need them all and they all have to move immediately."
But developing countries point out that most of the greenhouse gases in the atmosphere came from the industrialised world; whereas societies such as India remain desperately poor.
"[India] is a country where half the rural population does not have a light bulb in its home or a gas ring," said Ambassador Chandrashekhar Dasgupta, the senior Indian negotiator here.
"So to describe this country as a large emitter is absurd - there's no other word for it."
12 August 2009
Who Blinks First?
The latest exchange of views on the role of India in an international emissions reductions regime, from the BBC (emphasis added):