||Volcanic eruptions can have a profound effect on the Earth’s atmosphere and environment on all time scales. From being the source of most gases in the atmosphere over geologic time to producing climate change detectable over the past millennia, to threatening aviation, volcanic eruptions provide a strong link between Earth’s activity and its influence on the atmosphere and human history. To better understand these phenomena, the International Association of Volcanism and Chemistry of the Earth’s Interior (IAVCEI) and the International Association for Meteorology and Atmospheric Sciences (IAMAS) formed the Commission on Volcanism and the Earth’s Atmosphere at the AGU Chapman Conference on “Climate, Volcanism and Global Change” in Hilo Hawaii in 1992 following the largest eruption of the 20th Century, Mt. Pinatubo in 1991. On June 17-21, 2002, the same groups sponsored a second 10th anniversary Chapman Conference in Santorini, Greece, entitled “Chapman Conference on Volcanism and the Earth's Atmosphere”, which also resulted in publication of an AGU monograph.