A primary goal of the Durban Platform negotiations should be to develop an agreement that will maximize reductions in greenhouse gas emissions over time. Achieving this objective will be a function of not only the ambition of the 2015 agreement, but also the levels of participation and compliance by states. A higher level of ambition will not necessarily make the agreement more effective, if fewer states participate or comply. This paper analyzes the goal of the Durban Platform negotiations, the role of the 2015 agreement in promoting that goal, and the different options for a hybrid approach.