At meetings in Bonn and Marrakech in 2001, the Conference of the Parties to the Framework Convention on Climate Change broke through an impasse on the detailed provisions needed to allow the Kyoto Protocol to enter into force. Key ingredients in the breakthrough included U.S. withdrawal from the process, an effective relaxation of emissions targets for Japan, Canada, and Russia, and provision of access to unrestricted emissions trading. We analyze the costs of implementation and the environmental effectiveness of the Bonn-Marrakech agreement, and its effect on the relative roles of CO₂ vs. non-CO₂ greenhouse gases. The ability of the major sellers of permits, notably Russia and Ukraine, to restrict access to permits, and the ability to trade across all greenhouse gases controlled under the Protocol, are both found to have a significant effect for both costs and effectiveness. Finally, the implications of the agreement for the future evolution of the climate regime are explored. / Abstract in HTML and technical report in PDF available on the Massachusetts Institute of Technology Joint Program on the Science and Policy of Global Change Website. (http://mit.edu/globalchange/www/) / Includes bibliographical references (p. 16-17).