 MacDonald also published work on other aspects of climatology, hypothesizing the role of Milankovitch cycles and methane clathrates as drivers of natural climate changes.In 2002, he published a book involving his research with fellow JASON physicist Richard A. Muller.A member of the National Academy of Sciences (elected at the age of 32), the American Academy of Arts and Sciences, and the American Philosophical Society, MacDonald was also the recipient of the James B. Macelwane Medal of the American Geophysical Union (1965).