The social cost of carbon (SC-CO2) is an economic metric intended to provide a comprehensive estimate of the net damages - that is, the monetized value of the net impacts, both negative and positive - from the global climate change that results from a small (1-metric ton) increase in carbon-dioxide (CO2) emissions. Under Executive Orders regarding regulatory impact analysis and as required by a court ruling, the U.S. government has since 2008 used estimates of the SC-CO2 in federal rulemakings to value the costs and benefits associated with changes in CO2 emissions. In 2010, the Interagency Working Group on the Social Cost of Greenhouse Gases (IWG) developed a methodology for estimating the SC-CO2 across a range of assumptions about future socioeconomic and physical earth systems. Valuing Climate Changes examines potential approaches, along with their relative merits and challenges, for a comprehensive update to the current methodology. This publication also recommends near- and longer-term research priorities to ensure that the SC- CO2 estimates reflect the best available science. Table of Contents Front Matter Executive Summary Summary 1 Introduction 2 Framework for Estimating the Social Cost of Carbon 3 Socioeconomic Module 4 Climate Module 5 Damages Module 6 Discounting Module 7 Long-Term Research Needs References Appendix A: Biographical Sketches of Committee Members and Staff Appendix B: Presentations to the Committee Appendix C: Elicitation of Expert Opini Appendix D: Global Growth Data and Projections Appendix E: Comparison of a Simple Earth System Model to Existing SC-IAMs Appendix F: Empirical Equation for Estimating Ocean Acidification Appendix G: Damages Model-Specific Improvement Opportunities