James Edward Hansen (born March 29, 1941) is an American adjunct professor in the Department of Earth and Environmental Sciences at Columbia University. Hansen is best known for his research in the field of climatology, his testimony on climate change to congressional committees in 1988 that helped raise broad awareness of global warming, and his advocacy of action to avoid dangerous climate change.In recent years, Hansen has become a climate activist for action to mitigate the effects of climate change, which on a few occasions has led to his arrest.He is one of two winners of the 2010 Blue Planet Prize by the Asahi Glass Foundation of Tokyo, which is described as the “Nobel prize for the environmental sciences.”