I suggest that arranging global agreements on global problems such as climate change and biological diversity conservation is impossible when there are 192 states, thousands of organizations, thousands of indigenous nations and thousands of individuals meeting in a single room. A new approach is necessary.
Since Climate Change is essentially a problem of both global and eco-niche dimensions (as is the debate about biological diversity conservation), it is more sensible that hundreds of agreements at the eco-niche or sub-regional level get settled one at a time. Once there is a critical mass of agreements in a region there should be a regional agreement negotiated. The regional agreements, once settled should be banded together into a single global agreement (already ratified at the regional level) and affirmed by the UN General Assembly.
Piece-by-piece the problems would be negotiated and settled.
Yes, it would take some time, but let's be realistic: It is already taking more than two decades to arrange global agreements.
Shift gears and recognize that global problems are truly local. Make the local agreements and then build the global consensus.
A much better idea than trying to get agreement between thousands of self-interested individuals, governments and organizations that have no basis for compromise or agreement. Organize agreement between those most directly affected at every local or sub-regional level... settle the problem and move on to implementation in all of the various ways implementation is appropriate.