"In the nick of time, negotiators in Warsaw delivered just enough to keep things moving," said Jennifer Morgan, of the World Resources Institute, an environmental think tank.
The conference also advanced a programme to reduce deforestation and established a "loss and damage" mechanism to help island states and other vulnerable countries under threat from rising seas, extreme weather and other climate impacts.
The wording was vague enough to make rich countries feel comfortable that they weren't going to be held liable for climate catastrophes in the developing world.
The US and other rich countries also resisted demands to put down firm commitments on how they plan to fulfil a pledge to scale up climate financing to developing countries to US$100 billion ($122 billion) by 2020.
That money is meant to help developing countries transition to cleaner energy sources and adapt to shifts in climate that can affect agriculture, human health and economies in general.
"I think we had a good outcome in the end. It was quite a tough negotiation," US climate envoy Todd Stern said.
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. So far they've failed to reduce those emissions.
Historically, most emissions have come from the industrialised nations, but the developing world is catching up fast, driven by rapid growth in major countries including India, Brazil and China, the world's top carbon polluter.
Though China has invested heavily in renewable sources it's reluctant to promise emissions cuts internationally because it still gets almost 70 per cent of its energy from coal, which produces the highest emissions of all fuels.
The talks were paralysed for hours until China and India dropped demands for a reference to an article in the 1992 UN convention on climate change that says only developed countries are required to make commitments to cut emissions.
Western countries want to get rid of that "firewall" in the new climate deal, which countries have agreed should be applicable to all.
"In my understanding the firewall exists and it will continue to exist," Indian Environment Minister Jayanthi Natarajan said, indicating the issue is far from resolved.
The Warsaw conference called on parties to announce their offers to rein in or cut emissions by the first quarter of 2015 if they are "in a position to do so". But it gave little detail on what kind of information should go into those offers.
"Unfortunately, they failed to agree on what process and criteria they would use to evaluate the adequacy and fairness of each other's proposed actions," said Alden Meyer of the Union of Concerned Scientists.
It also remains unclear what legal form the agreement should take.
Environmental activists, many of whom walked out of the talks in protest on Friday, called the conference a failure for failing to deliver strong commitments to address climate change, and pointed to Typhoon Haiyan's devastation in the Philippines as a sign of urgency.
"Negotiators in Warsaw should have used this meeting to take a big and critical step towards global, just action on climate change. That didn't happen," said Samantha Smith, a climate activist at the World Wildlife Fund.
"This has placed the negotiations towards a global agreement in 2015 at risk."
Key points
*Countries reaffirmed the core principle that the deal will be "applicable to all'' 195 parties to the UN climate convention - with no differentiation between rich and poor nations as under the pact's predecessor the Kyoto Protocol.
*Parties should volunteer targets for curbing climate-altering greenhouse gas emissions "well in advance'' of a Paris conference where the deal must be inked in two years' time.
*Negotiators agreed to set up the "Warsaw international mechanism for loss and damage'' to assist vulnerable countries deal with future harm from climate damages they claim are no longer avoidable.
*The UN's Adaptation Fund, which helps poor countries deal with the effects of climate change, received pledges of US$100 million.
- AP, additional reporting AAP
