US Secretary of State John Kerry speaks during a plenary session at the 20th UN Climate Change Conference COP20 in Lima, Peru.
AFP/Lima
Negotiations on a pact to curb climate change entered their final day on Friday with a push to break gridlock among rich and poor countries.
Progress in the December 1-12 talks has been hampered by the revival of a years-old squabble over sharing responsibility for cutting greenhouse-gas emissions.
On Thursday, US Secretary of State John Kerry urged developing nations to ease their stance, saying they too would have to roll back carbon pollution from burning 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 industrialisation 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."
Countries disagree on how the long-standing principle of "differentiation" will be applied in a process next year of declaring national carbon pledges.
Developing nations say the West should bear a bigger burden for 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.
Developing nations also demand that pledges incorporate not only action on reducing carbon emissions, but also financial help and adaptation aid to shore up their climate defences.
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."
A format for the pledges must be agreed in the Peruvian capital to allow countries to start their submissions from the first quarter of next year.
They will be at the core of a global climate pact that nations have agreed to sign in Paris in December 2015 and will take effect by 2020.
It would limit average global warming to two degrees Celsius over pre-Industrial Revolution levels.
Scientists say 2 C is relatively safe, but still no guarantee against worsening drought, floods, storms and rising seas.
A blueprint for the 2015 agreement must also be approved in Lima.
UN Secretary General Ban Ki-moon urged ministers and officials on Thursday to begin "real, serious negotiations."
"We have been talking over the last two decades," said Ban. "We don't have a moment to lose."
But delegates reported a souring mood, and many expected the talks to run into overtime, following the trend of years past.
Scientists warn that on current carbon trends, the planet is on course for around 4 C of warming this century, dooming future generations with hunger, homelessness and disease spread.
