Along with his distinguished research career as a biological oceanographer and marine biologist and his inspiring service as a teacher, advisor, and mentor to students and junior colleagues at Harvard University, Jim McCarthy has been a scientific statesman of the first order, bringing insights from his research and his deep understanding of the role of science in society into the arenas of management of scientific enterprises and public and policy-maker education about the science relating to some of the greatest challenges of our time. His roles at the intersection of science with public issues have included stints as director of the Harvard Museum of Comparative Zoology, cochair of the Working Group II (Climate Change Impacts, Adaptation, and Vulnerability) for the Third Assessment of the Intergovernmental Panel on Climate Change, president of the American Association for the Advancement of Science, chair of the Board of the Union of Concerned Scientists, chair of the Scientific Committee of the International Geosphere-Biosphere Program, vice chair of the New England Climate Impact Assessment, and member of the U.S. Arctic Research Commission, among others. In all of these roles, he has been a model of insightful leadership, selfless service, integrity, and commitment to science and the public interest.