Nations will have to roll up their sleeves and make important compromises to meet the deadline, just 14 months off, for a global pact on curbing climate change, observers say.
Worrying signs of obstinance emerged from six days of UN talks in Bonn which ended Saturday.
Experts said those discussions fell short of their goal to set parameters for a ministerial-level drafting meeting in Lima in December for a deal to be inked the following year.
"There are some danger signals about the way we're coming out of here. We're not as far along as I'd hoped we would be," Alden Meyer of the US-based Union of Concerned Scientists told AFP.
"Some of those visions that are on the table, quite frankly, are not compatible... two opposite views of the world. Choices are going to have to be made."
The six-day talks in the former West German capital ended with nations still divided loosely along developed-developing country lines on the most fundamental aspects of who will be required to do what to halt the march towards dangerous levels of climate change.They agree the best tool is to curb Earth-warming fossil fuel emissions, which requires an expensive shift to less-polluting energy sources.
But poorer nations, many of them facing the highest risks from a predicted increase in climate change-induced sea-level rise, floods and droughts, insist the developed world must bear greater responsibility given their longer history of emissions dating back to the Industrial Revolution.
Rich countries, in turn, point the finger to countries like India and China, which are now among the major emitters as coal powers their economic development.
And these are issues many wished had been resolved by now, so that actual bartering can start on the text of the agreement that must enter into force by 2020 to meet the goal of limiting warming to two degrees Celsius (3.6 degrees Fahrenheit) from pre-industrial levels.
"The talks here can't fairly be called negotiations. They were discussions, sharing of views, but no actual elbows on table dealing with text. I can't see how they'll pull the elements together if they continue like this," said Meena Raman of the Third World Network NGO.
- Missed opportunity -The most anticipated outcome from Bonn had been progress on detailing what information nations will have to provide when they pledge emissions curbs -- things like which gases must be cut, by how much, and over what period.
A deadline for pledges, the building blocks for the Paris pact, has been set for the first quarter of 2015, for those countries that are able to do so.
Many felt that a draft negotiating text adapted during the course of the Bonn negotiations represented a step backwards, however, watering down a reference to the need to assess whether national pledges, combined, were sufficient to meet the 2 C goal.
"This draft completely changes the purpose of INDCs (intended nationally determined contributions) from being the contribution of each country to meet the ultimate objective... to what each country could minimally do," commented the Climate Action Network of NGOs.
"Everything is left to the objectivity of countries."
In terms of the Paris pact, which Bonn negotiators were also meant to start fine-tuning, countries remain divided on such fundamentals as what should be in it, whether it would be internationally binding, and whether the same rules would apply to all.
"Governments... missed an opportunity to shift gears in negotiations towards the global Paris agreement on climate change due at the end of next year," said Mohamed Adow of Christian Aid, a development charity that closely follows the talks.
The meeting's co-chairman Artur Runge-Metzger urged negotiators Saturday to "redouble" their efforts, and announced two additional meetings for next year, besides the usual June gathering in Bonn, to prepare for Paris.
The first will be held in Geneva from February 8-13, and the other in the second half of the year.
Many negotiators and observers believe the very format of negotiations should change from posturing in big, joint gatherings, to smaller, informal groups hammering out details.
"I think if they continue doing everything in this one group, they're literally going to run out of time. There are so many different issues and so many different options on the table," Meyer said.
Added Raman: "Many developing countries have been calling for text-based negotiations since March this year -- it needs to happen now. They need to break out and get their pens out and actually cross out text or scribble new text in the margins."
Developing nations also argue that a breakdown in trust can be repaired, at least partly, by rich countries putting money on the table at a pledging conference of the Green Climate Fund in Berlin in November.