Professor Michael B. McElroy received his Ph.D. from Queen’s University in Belfast, Northern Ireland. In 1970, he was named Abbott Lawrence Rotch Professor of Atmospheric Sciences at Harvard University, and in 1975 he was appointed director of the Center for Earth and Planetary Physics. He served as Chairman of the Department of Earth and Planetary Sciences from 1986 to 2000. He was appointed director of the newly constituted Harvard University Center for the Environment in 2001 in which he leads an interdisciplinary study on the implications of China’s rapid industrial development for the local, regional and global environment. In 1997, he was named the Gilbert Butler Professor of Environmental Studies. He is a Fellow of the American Academy of Arts and Sciences. McElroy’s research interests range from studies on the origin and evolution of the planets to, more recently, an emphasis on the effects of human activity on the global environment of the Earth. He is the author of more than 200 technical papers contributing to our understanding of human-induced changes in stratospheric ozone and to the potential for serious disruptions to global and regional air quality and climate due to anthropogenically related emissions of greenhouse gases. His recently published text, “The Atmospheric Environment,” provides a comprehensive introduction to the atmosphere, highlighting changes that occurred in the past while offering context for the disturbances underway today as a consequence of human activity.