Dr. James Hansen, an American atmospheric scientist and director of NASA's Goddard Institute for Space Studies (GISS). Hansen's main research interests now lie in the study of world climate trends and in developing global climate models. Hansen was trained as a space physicist at the University of Iowa. One of his most significant pieces of early work was the determination of the physical properties of the clouds that surround Venus. Photographed in his office at GISS in 1991.