Developed countries and fast-growing economies have reached a last-minute compromise to avert a breakdown of UN climate talks in Warsaw.
Talks were deadlocked after China and India clashed with the US and other developed countries on how to pave the way for a new agreement to fight global warming.
The stalemate was unlocked by a compromise that called on all countries to prepare "contributions," rather than "commitments" for the new deal, which is supposed to be adopted in 2015.
Such wording would leave countries with wider latitude in what kind of emissions targets to propose.
In Warsaw, negotiators were supposed to lay the foundation for a 2015 climate deal in Paris that countries have agreed should apply to them all. But negotiators struggled to agree on texts on emissions targets and climate aid for developing countries as talks continued past their scheduled end on Friday.
After all-night wrangling, Chinese negotiator Su Wei requested a reference to an article in the 1992 UN convention on climate change that says only developed countries are required to rein in their emissions.
US climate envoy Todd Stern said: "I hope I'm wrong about what I heard, but it would certainly be disappointing to move backward in time, not forward toward Paris."
Countries agreed on the compromise wording, allowing the conference to continue with a final session on Saturday.
The UN climate talks were launched two decades ago after scientists warned that humans were warming the planet by pumping CO2 and other heat-trapping gases into the atmosphere, primarily through the burning of fossil fuels.
Countries made progress on Friday on advancing a programme to reduce deforestation in developing countries, an important source of emissions because trees absorb carbon dioxide.
Climate financing proved harder to agree on. Rich countries have promised to help developing nations make their economies greener and to adapt to rising sea levels, desertification and other climate impacts.
They have provided billions of dollars in climate financing in recent years, but have resisted calls to put down firm commitments on how they are going to fulfil a pledge to scale up annual contributions to 100 billion dollars by 2020.
Pointing to the devastating impact of Typhoon Haiyan in the Philippines, island nations also demanded a new "loss and damage mechanism" to help them deal with weather disasters made worse by climate change. Rich countries were seeking a compromise that would not make them liable for damage caused by extreme weather events.