The idea is that COP21 needs to produce a substantial, conclusive, legally binding agreement to reduce carbon emissions. In order to do so, negotiators need a basis to work with. This basis is provided by INDCs, or Intended Nationally Determined Contributions- documents containing countries’ pledges about the amount of emission reductions they are willing to undergo. These documents are not yet legal commitments, but they are a start!
Around 40 thousand delegates are expected to participate in the climate negotiations, with many world leaders (such as Barack Obama and Xi Jingping) taking part as well. Most of them will be primarily concerned with their national interests, but the political landscape seems far more promising leading up to COP21; in fact, G7 countries have agreed to aim for full decarbonization by 2100 (which, although not optimal, is a good start).
As for the technical parts of it, the conference will be rather complicated.
The Long Term Goal (LTG) in the conference would include a 100% decarbonized world by 2050 (half a century earlier than what the G7 countries have agreed to). In the current scenario, negotiations will focus on both the pre-2020 action and the post-2020 predictions, with an emphasis of phasing out fossil fuel usage.
Some aspects that will be discussed include the scientific adequacy of the deal, which would prevent ‘backsliding’- and would only allow for increases in the commitments, rather than decreases. This would ensure that the goals which are now set are complementary to what science has shown is a valid target. Furthermore, as many of the INDCs are currently conditional, it would be necessary to create a way to ‘fulfill’ the conditions and maximize commitments. Much legal work is also needed, in order to avoid legal loopholes and make sure every country is on the same page.
An additional Global Adaptation Goal is set in order to equalize the playing field for all countries- as many of the still-developing countries need to see an indicator of willingness from the side of current economic powerhouses, it is necessary to form mechanisms (such as funds) that guarantee sufficient financing, both for the prevention of catastrophes and for ‘loss and damage’- dealing with them.
Despite the technical complexity, COP21 is essentially a conference in which nations around the world will need to come to difficult compromises, ones which will determine our approach to climate change for years to come.