This letter aims to help scholars and practitioners alike prepare for the 15th Conference of the Parties (COP15) to the United Nations Framework Convention on Climate Change (UNFCCC), to be held in Copenhagen in December 2009, by providing a bird's eye view of the increasingly complex terrain of the global climate negotiations. It identifies and explains the most important and contentious 'tripping points' for reaching any agreement on a post-2012 framework, by explaining the primary barriers among countries to reaching consensus and the bargaining chips that countries may draw upon to get there. Namely, the letter details the contours of the ongoing debates on: developed and developing country mitigation; reducing emissions from deforestation and forest degradation (REDD); technology transfer; adaptation; and finance.