On November 30, world leaders from 200 countries will convene in Paris, France for the 21st annual United Nations Climate Change Conference (COP21) to discuss what needs to be done to slow the imminent threat of climate change.

There’s a lot at stake. Greenhouse gas emissions are on path to breach a dangerous threshold that climate scientists say will make global warming irreversible—resulting in catastrophic consequences.

Running Out of Time

As The Guardian reports, at the current rate, the carbon budget (which is how much nations can emit before hitting the threshold) is on track to be used up within the next 30 years. That means the next generation will be left to face the droughts, floods, extreme storms, and other dire effects without the chance to turn things around.

Currently, the threshold is set at 2-degrees Celsius. At the last UN Climate Conference, countries committed to keeping within it over the next century. It may not seem like a lot, but considering the current level of global greenhouse gas, emissions must fall by up to 70 percent by 2050. If they don’t, scientists expect global warming could increase up to 6 degrees.

The (Urgent) Line in the Sand

COP21 is intended to organize a “Paris Climate Alliance” that would instruct the global effort to stay within the threshold and set up a formal agreement to hold countries accountable. Along with a legal agreement enforcing specific rules and mechanisms to maintain momentum, the alliance will work to ensure financial support is available for developing countries trying to transition to more efficient economies.

As a precursor to the conference, countries have had to submit pledges for how they plan to cut down on carbon—and by how much. The Intended Nationally Determined Contributions (INDCs), submitted in October ahead of the conference, show that—collectively—countries hope to cut emissions by a large degree but are still falling short of whats required to stay within the threshold.

According to a UN analysis conducted Oct. 30, if implemented as is, the INDCs could lead to more than 3-degrees of warming.

Still, this is the first time all countries have produced INDCs, and there’s agreement on the urgent need to act. In previous agreements, rich nations were exclusively responsible for cutting carbon consumption.

Still Not a Panacea

There will be many other obstacles to get through though, and according to a report by experts at the Brookings Institution, the conference will be most successful as the beginning something bigger:

“The Paris summit must not be regarded as a one-off opportunity to fix targets. Instead, it must be the first step of many, based on regular reviews of how close we are to meeting the goal of avoiding dangerous global warming. “More broadly, the Paris summit is a chance to build an understanding not only of the threats and risks from unmanaged climate change, but also the opportunities that lay in the low-carbon transition—including the path it paves to fight global poverty.”

The global consensus leading up to the conference, at least, is cause for optimism, even if the goals outlined are ambitious. The agreement that comes out of COP21 marks a turning point in world-wide collaboration to take on climate change.

The Long Game

Earlier this month, Christiana Figueres, the head of the UN Climate Change Secretariat said she was confident COP21 will be successful during a Reddit Ask Me Anything (AMA) session.

“I have been pellucidly clear that the agreement in Paris is not going to reach a 2-degree limit on temperature rise as though that were something we can take off a magical shelf and put on the table,” Figueres says. “I have been equally clear that getting us on to the 2 degree pathway is entirely possible.”

She explains that the agreement will enable countries to move in the right direction—even if they aren’t able to make the necessary changes immediately.

“This first set of INDCs is a departure point and not a destination,” Figueres explains. “The Paris agreement will construct a path of ever-increasing emission reductions with periodic checkpoints of progress until we get to the 2 degree pathway.”