Volcanoes, nuclear war, and solar geo-engineering. With a research portfolio that includes all three, Alan Robock is used to thinking about sudden, catastrophic change. A professor of environmental science at Rutgers University, Robock studies the movement of small particles and liquids through Earth’s atmosphere. In that role, he studies some very large and particle-producing events: sudden extrusion of many tons of sulfur from an erupting volcano, or the global convection of smoke and ash from the firestorms that would follow a nuclear war.