The Panel on Advancing the Science of Climate Change, one of five groups convened under the America’s Climate Choices suite of activities (see Foreword), was charged to address the following question: “What can be done to better understand climate change and its interactions with human and ecological systems?” The panel was asked to provide a concise overview of past, present, and future climate change, including its causes and its impacts, then to recommend steps to advance our current understanding, including new observations, research programs, next-generation models, and the physical and human assets needed to support these and other activities. The panel was instructed to consider both the natural climate system and the human activities responsible for driving climate change and altering the vulnerability of different regions, sectors, and populations as a single system, and to consider the scientific advances needed to better understand the effectiveness of actions taken to limit the magnitude of future climate change and to adapt to the impacts of climate change. (The full statement of task of the Panel on Advancing the Science of Climate Change can be found in Appendix B, and its membership can be found in Appendix A; full biographical sketches of the panel members can be found in Appendix C.)

In response to this charge, the panel first assessed what science has learned about climate change and its impacts across a variety of sectors, as well as what is known about options for responding to climate change in those sectors. An overview of this analysis is provided in Chapter 2, and the details can be found in the technical chapters (Chapters 6-17) that compose Part II of the report. The panel also identified scientific advances that could improve our present understanding of climate change or the effectiveness of actions taken to limit its magnitude or adapt to its impacts. Seven crosscutting research themes, presented in Chapter 4, were identified based on this analysis. Finally, the panel evaluated actions that could be taken to achieve these scientific advances, including the physical and human assets required. Chapter 5 includes the panel’s recommendations on these important topics.