International climate regimes: Effects of delayed participation

This paper analyses how delayed participation by regions can affect international climate regimes in terms of the feasibility, costs, timing, magnitude and nature of the long-term mitigation response. We use the energy-systems optimization model MESSAGE to construct several climate change mitigation scenarios with various levels of regional participation in short-to-mid term. By comparing these with a global scenario that assumes full spatial and temporal flexibility throughout the century, we are able to evaluate how participatory decisions affect the mitigation response as well as the costs and technology choices. We find that short-term postponement of participation from some regions can often lead to a delay of mitigation measures on the global level. However, if the regional delay lasts until mid-century, participants of the regime are likely to increase their efforts in the short term. Mitigation costs are found to substantially increase as a result of delayed participation—the extent of the increase depends on the relative importance of the region that postpones its participation, the stringency of the climate target and the ability to reorganize mitigation measures. Our analysis also shows that a region's decision to delay its participation in an international climate regime can lead to accumulated inertia in its energy system and thus to a delayed ‘technological transition’ toward a low-carbon future.