The distribution and magnitude of emissions mitigation costs in climate stabilization under less than perfect international cooperation: SGM results ☆ Katherine Calvin a, ⁎, Pralit Patel b , Allen Fawcett c , Leon Clarke a , Karen Fisher-Vanden d , Jae Edmonds a , Son H. Kim a , Ron Sands e , Marshall Wise a a The Pacific Northwest National Laboratory, Joint Global Change Research Institute (JGCRI) at the University of Maryland, College Park, 5825 University Research Court, Suite 3500, College Park, MD 20740, USA b Joint Global Change Research Institute (JGCRI) at the University of Maryland, College Park, MD USA c U.S. Environmental Protection Agency's Climate Change Division, USA d Pennsylvania State University, University Park, PA USA e Economic Research Service, U.S. Department of Agriculture, USA abstract article info Article history: Received 7 April 2009 Received in revised form 18 June 2009 Accepted 18 June 2009 Available online 27 June 2009 Keywords: Climate change Emissions mitigation CGE models Leakage The EMF22 Transition Scenario subgroup explores the implications of delayed accession on limiting climate change to various radiative forcing levels. This paper focuses on the cost of limiting radiative forcing and the role that industrial leakage plays in scenarios of delayed accession. We find that delayed participation shifts the cost burden toward regions that take early action and away from regions that undertake mitigation later. However, the inefficiencies introduced by delay are so great that present discounted costs are higher in the delayed scenario for regions that delay as well as for regions taking early actions. An important element of these inefficiencies is industrial emissions leakage, that is non-participating regions increase their emissions relative to the reference case. In aggregate, industrial leakage rates are less than 10% if all regions of the world begin emissions mitigation by 2050—higher in carbon-intensive sectors and lower in low-carbon-intensity sectors. Additionally, we consider the implication of technology on carbon prices, the feasibility of limiting radiative forcing to low levels, and the incentives to overshoot the radiative forcing limit. © 2009 Elsevier B.V. All rights reserved. 1. Introduction Most of the literature exploring the feasibility and cost of meeting various long-term, global, environmental goals has employed idealized assumptions about the international policy environment 1 . In general it is assumed that all nations of the world undertake identical climate policies that employ perfect “where” and “when” flexibility. That is, emissions mitigation is undertaken wherever and whenever it is least costly. The purpose of the EMF22 study group is to examine the feasibility and cost of meeting various long-term, global, environ- mental goals in “less than perfect” regimes. In this study imperfection is introduced when some regions of the world participate in emissions limitation regimes, while others do not. In other words, what difference does delay in participation in international programs of emissions mitigation make? 2,3 While this study focuses on the combined effects of the Kyoto gases, much of the behavior in SGM (as with all models) is driven by efforts to limit the atmospheric concentration of CO 2 . As with other models, we find that the limited cumulative emissions associated with stabilization of atmospheric CO 2 concentrations implies an essentially “zero sum game” character to international emissions mitigation architectures. Compared with an “ideal” distribution of emissions mitigation over space and time, emissions mitigations that are not undertaken in a given place and time must be undertaken at another place or time. However, as the desired steady-state CO 2 concentration declines, shifting emissions over time becomes increasingly less tractable, leaving only shifts from one place to another. In other words, at low steady-state CO 2 Energy Economics 31 (2009) S187–S197 ☆ The authors are grateful to the U.S. Environmental Protection Agency for financial support for the research presented here. The authors also thank two anonymous reviewers for their helpful comments. The views expressed here are the authors' alone and should not be attributed to the organizations for which they are employed. ⁎ Corresponding author. E-mail address: katherine.calvin@pnl.gov (K. Calvin). 1 Several important exceptions to this generalization include Richels et al. (2008); Edmonds et al. (2008); and Keppo and Rao (2007); den Elzen and Meinshausen (2005), den Elzen et al. (2005), Berk and den Elzen (2001), and Valverde, L.J., M.D. Webster (1999). 2 The EMF22 scenarios do not consider other potential imperfections in emissions mitigation regimes. While the EMF22 international scenarios explore imperfections in the timing of emissions mitigation, they implicitly assume that when regions begin emissions mitigation that reductions are undertaken with “idealized” domestic policy regimes. That is, within a given region emissions mitigation is undertaken in whatever sector of the economy it is cheapest to do so. 3 Ultimately, all major economies of the world must participate in emissions mitigation to stabilize the concentration of CO 2 in the atmosphere. This follows from the fact that in the long-term cumulative emissions determine steady-state atmospheric CO 2 concentra- tions, at least on millennial time scales. See Kheshgi, Smith and Edmonds (2005). 0140-9883/$ – see front matter © 2009 Elsevier B.V. All rights reserved. doi:10.1016/j.eneco.2009.06.014