LIMA: Talks on a pact to curb climate change entered their final day on Friday, seeking an end to deadlock among rich and poor countries, amid appeals to avoid a weak compromise.

Progress in the December 1-12 talks has been hampered by a flareup in a years-old dispute over sharing responsibility for tackling the climate problem.

Efforts to overcome the row went into the night, setting the annual UN parlay on course for a familiar climax of haggling and frayed nerves.

Campaign groups warned that any face-saving fudge would be catastrophic for a pact due to be completed in Paris in December 2015.

“Heading into the final day of negotiations is like reading a choose-your-own adventure novel,” Jan Kowalzig, policy advisor for Oxfam, told AFP.

“The choices made today will either put us on a barely workable path leading into Paris or doom us to a dangerous future.”

Countries disagree on how a long-standing principle in UN talks called “differentiation” will be applied in national pledges to address climate change.

The pledges, scheduled to be put on the table next year, would be the core of the most ambitious environment accord in history.

The pact would take effect from 2020, screwing down emissions of greenhouse gases in order to keep global warming within two degrees Celsius (3.6 degrees Fahrenheit) over pre-industrial levels.

Developing nations in Lima have defended a long-standing principle that Western countries should bear a bigger burden for carbon cuts, having started decades earlier to pollute their way to prosperity.

But rich countries point the finger at developing giants like China and India furiously burning coal to power their rapid growth.

On Thursday, US Secretary of State John Kerry urged developing nations to realize they too would have to roll back pollution from fossil fuels, even if they felt it was unfair.

“I know the discussions can be tense and decisions are difficult, and I know how angry some people are about the predicament they've been put in by big nations that have benefited from industrialization for a long period of time,” Kerry said.

But, “we have to remember that today more than half of global emissions, more than half, are coming from developing nations. So it is imperative that they act, too.”

Between 2000 and 2010, the share of developed countries fell from 51.8 per cent to 40.9 per cent of the global emissions total, while that of developing countries surged from 48.2 per cent to 59.1 per cent, according to the UN Environment Program (UNEP).

Developing nations are also demanding that the roster of national pledges go beyond mere promises in emissions curbs.

To reflect the greater responsibility of rich countries, it should also incorporate pledges of financial help and “adaptation” aid to shore up the defenses of climate-vulnerable countries, they say.

With little movement by late Thursday, Peru's Environment Minister Manuel Pulgar-Vidal, who presides over the talks, called for constructive exchanges.

“We are in a time in which we should take decisions,” he said. “We don't want to leave Lima with empty hands.”

Adding to concern in Lima is that nearly two weeks of talks have inflated rather than reduced a proposed draft text for the agreement.

Cutting through the bloat could be a major headache in the complex process leading up to Paris.

UN Secretary General Ban Ki-moon urged ministers and officials Thursday to embark on “real, serious negotiations.”

“We have been talking over the last two decades,” said Ban.

“We don't have a moment to lose.” Scientists say 2 C of warming is relatively safe but still no guarantee against damage to the climate system.

On current carbon trends, the planet is on course for around 4 C of warming this century, dooming future generations to a planet of worsening drought, flood, storm and rising seas, they say.