COP21: 'It's time to come to an agreement'

An Eiffel Tower made of bistro chairs is seen covered in messages related to climate change at COP21, the United Nations conference on climate change in Le Bourget, France.

CNN Opinion columnist John D. Sutter is reporting on a tiny number -- 2 degrees -- that may have a huge effect on the future. You can subscribe to the "2 degrees" newsletter or follow him on Facebook, Twitter and Instagram. He's jdsutter on Snapchat. You can shape this coverage.

Le Bourget, France (CNN)It's crunch time for the fight against global warming.

And, despite ongoing conflict and uncertainty at the U.N. climate change summit here in Paris, optimism is still running high.
"It's time to come to an agreement," French Foreign Minister Laurent Fabius, who is presiding over this process, said in a meeting late Thursday night.
    "We must do this, and we can do this," he added. "I think, dear friends, that we will make it."
    They won't make it on time, though. Fabius, who serves as the president of the 21st Conference of Parties, or COP21, had wanted all 195 countries here to agree upon a legally binding framework for cutting carbon pollution by Friday at 6 p.m. in Paris.
    On Friday morning, however, Fabius told reporters that negotiators were not likely to reach an agreement until Saturday, according to CNN affiliate BFM.
    Weary negotiators have been working overnight to create a deal that would be the culmination of more than two decades of work on climate change.
    The outcome of the agreement could help determine the fate of the planet.
    And success may lie with a relatively little-known group called the "High Ambition Coalition."
    Their members come from countries large and small, rich and poor.
    Yet they've come together -- these government ministers from 100 or so nations -- to try to get the world to do the impossible: Ditch fossil fuels. They want to see pollution cut so rapidly that we actually may be able to avoid the most disastrous effects of climate change, including super droughts, deadlier heat waves, mass extinctions of plants and animals, mega-floods and rising seas that could wipe some island countries off the map.
    This broad group of countries, which includes the United States and EU as well as developing nations in Africa, Latin America and the Pacific Islands, isn't an official negotiating body at the U.N. conference. But has rallied broad support for trying to squeeze as much "ambition" out of the process as possible.
    This is key if the agreement reached is going to actually be "universal, legally binding, ambitious, fair and lasting," as Fabius contends it should be.
    "If you want to be on the right side of history on climate change you need to stand for some basic principles," said Jake Schmidt, a climate expert at the Natural Resources Defense Council. "They're trying to show other countries that there's a significant group that wants to be in this camp."
    Many members of this alliance are pushing for climate goals that would have been unthinkable only weeks ago. Among them: a 1.5 degree Celsius limit for warming since the industrial revolution.
    For years, 2 degrees Celsius has been the de facto number at the center of international climate talks. Now countries from the United States to Germany, Canada and the Marshall Islands are supporting this more-stringent goal as part of the agreement; and that wording appears in the latest draft of the accord.
    That may sound insignificant to you, but I'm sure it doesn't to Tony de Brum, the foreign minister of the Marshall Islands, a country that scientists say likely won't exist if temperatures warm 2 degrees. The islands, in the distant Pacific Ocean, are so low to the water that rising ocean levels could drown them entirely.
    "There is a clear recognition that the world must work towards limiting warming to below 1.5 degrees Celsius, and that it would be much safer to do so," de Brum said in a statement issued early Friday. "With this, I would be able to go home and tell my people that our chance for survival is not lost."
    That language is strong.
    But it doesn't guarantee these climate talks will succeed.
    Many others -- notably the Copenhagen talks in 2009 -- have failed miserably.
    There are serious questions about whether the 1.5 degree goal is achievable without new technology.