They fought about money, categories and assessments. They skirmished over scopes and road maps and timetables.

But the true battle consuming leaders from 198 governments at a U.N. global warming conference that concluded yesterday after two weeks of negotiations and 32 hours of overtime debating was really about just one thing: balancing responsibilities between poor, rich and richer nations.

"This, in a way, begins the future of whatever will follow as a replacement of the Kyoto Protocol, so it is from one generation to another. So for that reason, it is difficult," said France's ambassador for climate change, Laurence Tubiana. Her country hopes to host the signing of a new global agreement next year in Paris.

Emerging from a makeshift plenary tent along with other bedraggled delegates just after 2 a.m. on Sunday, Tubiana and others praised the Lima Accord for Climate Action as putting them on a path to creating a deal in 2015. But they also acknowledged that the long-simmering debate over how to redesign the climate regime will almost certainly come to a boil again in Paris.

"We have been talking about this for a very long time. This is the issue that is probably, historically, the most contentious in these negotiations," said U.S. Special Envoy for Climate Change Todd Stern. "It will come up again."

If countries succeed in creating a hoped-for new international global warming accord next year in Paris, it could turn the decades-old system for dealing with climate change on its head. No longer would wealthy countries alone be expected to take unilateral cuts while paying poorer nations to lower emissions voluntarily—a design that kept the United States an outlier.

Instead, countries of all levels of development would cut carbon after 2020. While money and assistance would be delivered to developing countries, it would not be a quid pro quo.

But that model of a new system, supported by the United States, Europe and even some coalitions of developing countries, is viewed as threatening to many governments worried about the implications of having to take on new responsibilities.

Historical grievances haunted the night
That fear all but brought negotiations to a standstill Saturday morning. Negotiators had already blown past their 6 a.m. Friday deadline, unable to agree on—among other things—what information countries should include when they unveil their post-2020 targets early next year. Arguing into the dawn, negotiators came back to the plenary, some after just two or three hours of sleep, only to be faced with tirades about colonization and other historical grievances against the West.

What seemed like a wonky and legalistic categorizing section took on high drama as some developing countries tried to use the so-called Intended Nationally Determined Contributions (or INDCs) as a place to remind wealthy nations that there is and will remain a stark divide.

"Differentiation. Common but differentiated responsibilities. This is the core political thing," Claudia Salerno, lead negotiator for Venezuela, the country that led the charge against changing the current Kyoto system, said when asked what was at stake.

Invoking the U.N. principle that for many has come to mean that the categories of doers and those who may do will stay locked in place, Salerno said countries for too long have avoided talking frankly about the issue. It came to a head Saturday morning in an explosive plenary session where visions of colonization and other long-standing grievances were summoned up against the West.

"If we are ready to do so, why not start having at least face-to-face conversations on the issues? The momentum for having the discussion, it hit Lima and surprised everybody," Salerno said. "It seemed like the elephant in the room, and everybody pointed it out this morning. Maybe we need to talk about it."

'People are nervous' about a new approach
Jennifer Morgan, director of the World Resources Institutes's climate and energy program, said fear and lingering distrust between countries were the driving forces behind the Lima tensions.

"They are birthing a new approach," she said. "It's like a pre-negotiating of all the issues they have to decide next year. People are nervous that this is going to be it."

Seyni Nafo, lead coordinator of a group of African nations in the talks, said the new deal under discussion is a "totally new paradigm" for developing countries. "I think most of us don't even realize the implications of some of the decisions we make here," he said.

He argued that the system the United States is advocating weakens the rules for wealthy countries—they would be able to offer whatever carbon-cutting targets they saw fit and are pushing for a mostly voluntary system that does not demand compliance with the pledges. Meanwhile, he said, countries that have contributed the least amount to climate change have the lowest capacity to deal with it and are seeing new responsibilities even as they are still growing their economies.

"There's a number of reassurances we need. One of them is the provision of adequate finance," he said. "We're not dealing with climate science per se. We are very much dealing with development, with economic growth, with the pursuit of happiness."

He said poor countries are being forced to accept what some of them consider a weak deal for America's sake but argued that the United States isn't the only country with political challenges.

"We are told we can't miss this opportunity, because if we do, the U.S. can't join. Well, that's not our highest priority. If we have to do that at the cost of us taking unfair commitments, unfair burdens ... it's going to be very difficult for us to sell it at home."

Countries did find enough legal Band-Aids to patch together an agreement that finally won approval here, including the near-exact words of a landmark agreement in November between the United States and China that Stern said he and Chinese Minister Xie Zhenhua offered as a compromise. That language calls for an ambitious agreement that "reflects the principle of common but differentiated responsibilities and respective capabilities in light of different national circumstances."

Reprinted from Climatewire with permission from Environment & Energy Publishing, LLC., 202-628-6500