A rare amount of optimism marked the beginning of a climate change conference two weeks ago in Lima, Peru. Before the conference, President Barack Obama and Chinese President Xi Jinping stood side-by-side to announce the world’s biggest polluters would lower their greenhouse gas emissions. It was the first concrete sign that a strong agreement by next year may be within reach.  

Fourteen days later, Lima concluded in an atmosphere of exhaustion and disappointment. Negotiators reached an accord on Sunday, after talks ran into overtime and seemed at times on the verge of collapse. The agreement earned a mixed reception. “The Lima Accord delivers what we need to go forward,” U.S. Special Climate Envoy Todd Stern said. But many environmental groups were more skeptical. “We went from weak to weaker to weakest," Samantha Smith of the World Wildlife Fund said.

Both statements might be true. The Lima accord is both unprecedented and not ambitious enough. We have the bare-minimum framework for a climate conference in Paris next year, and this framework requires all countries to play a role in controlling carbon pollution. But it doesn’t answer some of the toughest questions, nor does it avert a dangerous level of global warming. 

What did Lima do?

The Lima Accord is unprecedented because it requires each of the 196 countries to propose action on climate change—a first. Countries face a rough deadline to submit domestic plans by the end of March. Once those proposals are published, policymakers and scientists will have time to review and compare these plans by November 2015. In theory, this lets world leaders pressure other nations to ramp up their ambitions.

Unlike the Kyoto treaty, which didn’t require cuts from China and India and wasn’t ever ratified by the U.S., Paris is meant to include all of the polluters, even the developing nations. The agreement covers up to 90 percent of global emissions. But to ensure this happens, policymakers have to bridge old divides. Developing countries still push for exemption from climate action, while industrialized countries want every country to act.

“The U.S.-China announcement last month hinted at a fundamental shift putting developed and developing countries on a more equal footing,” Elliot Diringer, Center for Climate and Energy Solutions Executive Vice President, said. It's no surprise that in Lima a lot of developing countries pushed back.”

Lima requires every country to submit a plan, but it does not determine what those targets might be. They can vary widely, and will be set by nations individually. For instance, the U.S. announced it will propose a target of 26 to 28 percent lower emissions by 2025, while China agreed to cap its emissions for the first time in 2030. 

What didn’t it do?

To ensure more than 190 countries were on-board, particularly the developing world, negotiators weakened much of the requirements for individual countries in the final 30 hours. 

Lima set out to establish a minimum guidelines for what information countries must disclose about cutting carbon pollution. The seemingly small detail is important because it lets countries compare apples to apples, and potentially push for more cuts. Except now the review process won’t be as vigorous as it could be, thanks to a single word change. Now, most of the information for these plans will be voluntary, rather than mandatory, because the text says countries “may” include detailed information, rather than “shall.”

In the end, some of the toughest decisions were simply postponed until Paris. At the core of the questions is whether the world will commit to net zero greenhouse gas emissions by the end of the century—crucial to limiting the worst effects of global warming. Other questions, like how countries plan to increase climate change financing to $100 billion annually, will be important to reaching a Paris agreement. 

There is little chance countries will reach a deal that limits global warming to 2 degrees Celsius (or 3.6 degrees Fahrenheit). This is the level most of the world agreed to by 2010, but we’re already on track to overshooting it, setting the world on pace for irreversible, and potentially devastating impacts. Countries would have to commit to more ambitious targets than they’re clearly ready for in order to stay within this range. 

What’s next? 

Despite the challenges ahead, an international climate change deal is far from dead. Some of the optimism has faded, but many experts maintain the talks are headed in the right direction. 

Robert Stavins, an economist with Harvard University and expert on global climate policy, said Lima could still be valuable in the long-term. The critics, he wrote at his blog, “ignore the geographic scope of participation, and do not recognize that—given the stock nature of the problem—what is most important is long-term action. Each agreement is no more than one step to be followed by others. And most important now for ultimate success later is a sound foundation, which is what the Lima accord provides.”

The World Resource Institute’s Global Director of the Climate Program Jennifer Morgan said in a statement that the “most inspiring development in Lima was an outpouring of support for a long-term effort to reduce emissions.”

Another way to look at it is just how far countries have come. In a short period of time, the debate shifted from whether countries even take climate change seriously to when and just how much they will plan to do.

“Last year, the debate was around whether or not countries would bring forward targets early next year,” said Jake Schmidt, international director of the Natural Resources Defense Council. “There’s no question about that date anymore. We know what’s happening in those countries. The big emitters are coming forward with targets.”

The Obama administration is partially responsible for the change in tone. The U.S. pledged $3 billion to the international Green Climate Fund ahead of Lima, after announcing its surprise agreement with China. 

“This was a hard meeting when no one expected it to be, but it shows we’re going to have to work really hard next year,” Schmidt said.