The sea ice surrounding Antarctica has increased in extent and concentration from the late 1970s, when satellite-based measurements began, until 2015. Although this increasing trend is modest, it is surprising given the overall warming of the global climate and the region. Indeed, climate models, which incorporate our best understanding of the processes affecting the region, generally simulate a decrease in sea ice. Moreover, sea ice in the Arctic has exhibited pronounced declines over the same period, consistent with global climate model simulations. For these reasons, the behavior of Antarctic sea ice has presented a conundrum for global climate change science. The National Academies of Sciences, Engineering, and Medicine held a workshop in January 2016, to bring together scientists with different sets of expertise and perspectives to further explore potential mechanisms driving the evolution of recent Antarctic sea ice variability and to discuss ways to advance understanding of Antarctic sea ice and its relationship to the broader ocean-climate system. This publication summarizes the presentations and discussions from the workshop. Table of Contents Front Matter Antarctic Sea Ice Variability in the Southern Ocean-Climate System: Proceedings of a Workshop References Appendix A: Statement of Task Appendix B: Definitions of Key Terms Appendix C: Acronyms and Abbreviations Appendix D: Workshop Agenda and Participants Appendix E: Invited Speaker Abstracts Appendix F: Biographical Sketches of Planning Committee Members

In 1999 the National Academies of Sciences, Engineering, and Medicine released a landmark report, Our Common Journey: A Transition toward Sustainability, which attempted to "reinvigorate the essential strategic connections between scientific research, technological development, and societies' efforts to achieve environmentally sustainable improvements in human well-being."1 The report emphasized the need for place-based and systems approaches to sustainability, proposed a research strategy for using scientific and technical knowledge to better inform the field, and highlighted a number of priorities for actions that could contribute to a sustainable future. The past 15 years have brought significant advances in observational and predictive capabilities for a range of natural and social systems, as well as development of other tools and approaches useful for sustainability planning. In addition, other frameworks for environmental decision making, such as those that focus on climate adaptation or resilience, have become increasingly prominent. A careful consideration of how these other approaches might intersect with sustainability is warranted, particularly in that they may affect similar resources or rely on similar underlying scientific data and models. ? To further the discussion on these outstanding issues, the National Academies of Sciences, Engineering, and Medicine convened a workshop on January 14?15, 2016. Participants discussed progress in sustainability science during the last 15 years, potential opportunities for advancing the research and use of scientific knowledge to support a transition toward sustainability, and challenges specifically related to establishing indicators and observations to support sustainability research and practice. This report summarizes the presentations and discussions from the workshop. Table of Contents Front Matter 1 Introduction 2 Decision Sciences, Demography, and Integrated Assessment Modeling 3 Urban Systems 4 Sustainable Manufacturing 5 Sustainable Food Systems 6 Ocean Sustainability 7 Paths Forward 8 Workshop Synopsis Appendix A: Workshop Agenda Appendix B: Workshop Participants Appendix C: Biographies of Planning Committee, Speakers, and Staff