Comparison of different climate regimes: the impact of broadening participation

Several studies have shown that international climate policy can only be effective and cost-efficient if all major emitting countries at some point of time participate in reducing greenhouse gas emissions. As illustration, even if the emissions of all OECD countries are reduced to zero over the next few decades, the more ambitious greenhouse gas concentration stabilization targets cannot be reached. Broadening participation is therefore an important priority for post-2012 climate policy agreement. Such participation does not necessarily need to take the same form and/or timepath for all countries. It may change dynamically over time, and linked to ongoing stringent reduction commitments with the aim of being able to ensure long-term concentration stabilization or temperature targets. From the outset, it has been acknowledged in the Climate Change Convention (UNFCCC) that countries have "common but differentiated responsibilities and respective capabilities"