Climate change is one of the best examples of global environmental problems. Countries are conscious that they have to find a solution to this global problem at the international level. Negotiations on climate change started more than 15 years ago with the signature of the United Nations Framework Convention on Climate Change. Since then, the process went through a series of conferences and protocols. Part of this process, the Kyoto protocol constitutes a major step since it designed country-specific targets defined in terms of CO2 emissions abatement. The fact is that we should not speak about an international environmental agreement but about a negotiation process to find a solution to an environmental problem. The negotiation starts with general and consensual principles but should evolve towards legally binding and more and more precise commitments from the parties. We can consider the whole process as a series of nested treaties. In this process, the uncertainty is not only in the scientific description of the climate change. It is also a consequence of the strategic negotiation of the different countries. The way the negotiation is organized conditions the result and the likelihood to reach an agreement. The institution available and the design of incentive mechanism play an important role. Our claim is that it is possible to take advantage of the parties’ risk aversion. This is a way to make them conscious of the benefit they can draw from an agreement. We describe a mechanism to implement this idea.