Project director of the United States Department of Energy’s Multistate Atmospheric Power Production Pollution Study, which focused on acid precipitation in the northeastern US, and was a program adviser for various components of DOE’s Carbon Dioxide Research Program, including serving as lead editor of two volumes of DOE’s 1985 assessments on climate change. From 1984 to 1990, he served as U.S. co-chair of Project 02.08–11 under Working Group VIII of the US/USSR Joint Committee on Cooperation in the Field of Environmental Protection. At LLNL, he served as deputy division leader for atmospheric and geophysical sciences from 1974 to 1987 and division leader from 1974 to 1987. From 1993 to 2002, MacCracken was on assignment from LLNL to the interagency Office of the U.S. Global Change Research Program in Washington D.C., as senior global change scientist. With the Office, he served as its first executive director from 1993 to 1997 and as executive director of the National Assessment Coordination Office from 1997 to 2001, coordinating preparation of the first comprehensive national assessment of climate change impacts on the US . During this assignment, MacCracken also served as a co-author/contributing author for various chapters in the assessment reports of the Intergovernmental Panel on Climate Change, as well as coordinating preparation of the official U.S. Government reviews of the Second and Third IPCC Assessment Reports. He also served as president of the International Commission on Climate from 1995 to 2003 and co-editor of volume 1 of the Encyclopedia of Global Environmental Change. From 2003 to 2007, MacCracken served as president of the International Association of Meteorology and Atmospheric Sciences and on the executive committees of International Union of Geodesy and Geophysics, members of which are the national academies of science or their equivalent in about 65 nations. He also was a member of the executive committee of the Scientific Committee for Oceanic Research from 2003 to 2011 and a member of the synthesis team for the Arctic Climate Impact Assessment from 2002 to 2004 . From 2004 to 202007 he served on a scientific expert group convened by Sigma Xi and the UN Foundation at the request of the UN Commission on Sustainable Development to suggest the best measures for mitigating and adapting to global climate change. MacCracken’s current research interests include climate engineering and the especially important role in limiting climate change that can be played by reduction in emissions of short-lived greenhouse gases and absorbing aerosols. He has also prepared several declarations relating to climate change, one of which was cited favorably by Justice Stevens in his majority opinion in the April 2007 decision by the US Supreme Court in the case of Massachusetts et al. versus the United States Environmental Protection Agency. MacCracken is a fellow of the American Association for the Advancement of Science, and a member of the American Meteorological Society, American Geophysical Union, the Oceanography Society, and Sigma Xi. He was a publicly elected member of the board of directors of the Livermore Area Recreation and Park District from 1970 to 1978. He also edited the book about Josiah Calvin McCracken, his maternal grandfather. He is the great-grandson of Henry Mitchell MacCracken, grandson of , son of Calvin Dodd MacCracken, and brother of Mark MacCracken. Since 2013, MacCracken has been listed on the Advisory Council of the National Center for Science Education.
