"This process is agreement by exhaustion. It's not the smartest way to work out key issues which should be driving the world forward, but that's the way it's done," a senior delegate at UN climate talks in Bangkok said this week.

The talks on how to fight climate change, which began on Monday, are due to end on Friday when a formal report for government policymakers is expected to be adopted by delegates from more than 100 countries.

"What will happen here is that we'll fiddle around for two and a half-days and then it'll be obvious that this thing has to be done in the last day and a half and that's what will happen," said the delegate, who asked not to be identified.

"It's just standard. It's exactly what happened in Paris and exactly what happened in Brussels," he said, referring to two previous reports this year by the Intergovernmental Panel and Climate Change (IPCC).

Both meetings, as well as recent annual Kyoto Protocol gatherings, ran deep into the night right at the end, when many delegates looked haggard.

"It's just such a strange atmosphere," said Martin Hiller, climate change spokesman for environment group WWF, citing the sheer intensity of negotiations and day after day with just four hours of sleep, particularly during Kyoto gatherings.

"And you get a strange satisfaction out of this sleep deprivation. Everybody has stakes in the whole thing and endurance is an essential part of it."

ARGUMENTS AND MIX-UPS

Arguments often break out over technical definitions, the meaning of words, demands that sentences be rephrased, removed or added as well as questions raised about scientific evidence of global warming and the ways to fight it.

Then there is political posturing by countries opposed to targets to cut greenhouse gases or any suggestion that they are to blame for global warming.

Add to this the need to translate the main meetings at any UN climate gathering simultaneously into the six official UN languages, and you have a recipe for stress and frustration.

The delegate said the use of the word "coalition" in a document nearly led to a walk-out by Spanish-speaking South Americans at a past UN climate meeting.

When translated from English, the word suggested a group of corrupt people. Changing the word to "group" averted a crisis.

Hiller said that while some of the arguments seemed petty, "in the end it's actually not an inefficient process". The fact that a small country could hold back a big country at these UN gathering was good and necessary, he said.

At the Bangkok meeting, governments have proposed hundreds of amendments to the main document, a 24-page summary for policymakers dealing with the science and estimated costs of curbing greenhouse gas emissions.

"If you try to debate the thing word by word, nuance by nuance among 180 people, then you just don't get anywhere. So the strategy is to push these things into small groups and then have the small groups report back," the delegate said.

"The other problem is that nothing is agreed until it's all agreed," he said. "That's where the negotiation by exhaustion comes in. It's the last person standing here that wins."