The way climate change manifests itself in different parts of the world, coupled with varying degrees of vulnerability to its consequences on living species and on economic situations, makes for complex negotiations.
What sort of concessions will governments make when lives and livelihoods are at stake because of a global phenomenon started by the industrial revolution in the 19th century, entrenched by industrialised development throughout the 20th and persistent in the 21st?
Tackling climate change is, however, not a competition. While stakes are high locally, they are, we are told by scientists and governments alike, essentially global. Clearly, one of the main hurdles faced by the delegations taking part in the COP21 is how to reconcile local and planetary considerations.
Among the difficult choices are such issues as agreeing on the greenhouse-gas emission reduction target. Should it be two degrees celsius or 1.5, for example, and how will that target be reached? Whether it will be enough to make a significant difference is another question. Is a strict and regular process of review of commitments necessary, desirable or feasible? Pledges on climate-change action have been coming in as requested ahead of COP21, not least of all from the biggest polluters, China and the United States. The pledges will need to be made concrete after the conference.
One question facing participants will be whether or not to make the COP21 final agreement or parts of it in the hopes that consensus is reached legally binding.
Two very big sticking points have to do with responsibility and money.
The United Nations body overseeing the Climate Change research and conference decisions (UNFCC) has a charter which, drawn up in 1992, says that the then-industrialised, rich countries broadly speaking, the G7 had caused the problem, and should bear the brunt of righting it. However today, China and India have caught up in this macabre race and are both in the top five of the carbon-emitters table.
That being said, the financing issue is tricky especially as economies change, as can be seen from the example of China or others since 1992. For instance, as of 2020, rich economies as they were in 2009 at the climate meeting in Copenhagen, COP15, promised to come up with some 90 billion euros a year in a Green Fund to help poorer countries cope with climate change and reach emission-capping action goals.
The mechanism for gathering and distributing the money has yet to be established. The so-called emerging or newly developed countries of Brazil, China, India and South Africa upped the ante at a four-way meeting in New York in June in issuing a joint statement in which they expressed their disappointment about the lack of a "clear roadmap" for the fund.
Looming at the COP21 will be the demand from the poorest countries for compensation for what they call loss and damage due to the consequences of climatic events. A sore point, and likely a sticking point at the conference in Paris.
Far from the negotiating tables and discussion rooms, hurdles exist at the grassroots level. Convincing the public that they will have to change their habits or lifestyles (or those they aspire to) in order to help cap global warming and prevent even worse consequences than those already happening, is yet another challenge for creative governance.