Thump, thump, thump. In the frantic last hours of U.N. climate talks in Scotland, a senior diplomat from Luxembourg came sprinting down a hallway inside the summit venue, his hair flying as he whooshed by clutching a sheaf of papers, only to vanish inside an office as abruptly as he appeared.

The final stretch of negotiations over what nearly 200 governments will do next about fossil fuels heating the Earth to disastrous levels was like that Friday: National delegations engaged in frenetic, often mysterious activity as they haggled to get as much of their position as possible into the final agreement from the talks in Glasgow.

U.S. diplomats mostly worked behind closed doors, with terse signs on the glass. The open doors of most other country's offices – South Korea, Ivory Coast, Austria, and others – showed rooms full of diplomats bent intently over their laptops, eyes fixed on screens and fingers flying over keyboards.

Chinese diplomats crowded into one of their offices stopped working, laughed and took photos when a wayward robin hopped in among them, lost in the warren of temporary tents and the event center.

In the office of India's delegation, there was muted excitement. Delegates sat cross legged on the floor, typing furiously on their laptops. A vase in the office held fresh pink lilies. Endless cups of chai flowed in preparation for what would be a long night.

The Indian delegation got "home-cooked meals" dinners during the conference, provided by a restaurateur who runs curry houses across Britain. Vegetarian curries served with Indian flatbreads called chapatti were usually on the menu.

The conference's cafes offer egg mayonnaise sandwiches, chicken mayonnaise sandwiches, and pork and pickle sandwiches, all on soft white bread. In two weeks, the words "I love this sandwich" have never been overheard.

The past few days have been a flurry of bilateral meetings for the Indian minister, Bhupender Yadav, and his top officials.

Some members of the delegation planned to return Saturday to India, where there are other challenges to tackle:, not least New Delhi's annual surge in air pollution that leaves its inhabitants gasping. But the "core team," including the minister and top bureaucrats, are set to fly out Sunday.

As the conference neared its end — it was scheduled to close on Friday evening, but went into overtime — there was hour after hour of negotiation over what what from the outside could seem like the nit-pickiest of wording issues for the final agreement. "Urges" vs. 'requests" was one raging debate Friday.

In fact, the distinction held significance for one of the biggest issues imaginable: how firmly nations commit to solid new steps to stave off a level of temperature rise  that promises to wipe out some of the nations represented in the talks.

"You know in common English, 'urge' is stronger," said Kelley Kizzier, a former climate negotiator for the European Union who attended the Glasgow talks as a climate advocate. In diplomatic language, however, "request" implies a legal requirement, and therefore carries more weight, she said.

How the linguistic cage match ends will determine whether countries have to ramp up their climate efforts again next year or can ride on this year's pledges for a while longer.

More inside knowledge from the climate talks: "The bigger the room, the less important the thing is that's going to happen," Kizzier said. "The nitty-gritty negotiations happen" in tiny groups.