James Edward Hansen (born March 29, 1942) is an American adjunct professor directing the Program on Climate Science, Awareness and Solutions of the Earth Institute at Columbia University. He is best known for his research in climatology, his 1988 Congressional testimony on climate change that helped raise broad awareness of global warming, and his advocacy of action to avoid dangerous climate change. In recent years he has become a climate activist to mitigate the effects of global warming, on a few occasions leading to his arrest. Early life and education Hansen was born in Denison, Iowa, to James Ivan Hansen and Gladys Ray Hansen. He was trained in physics and astronomy in the space science program of James Van Allen at the University of Iowa. He obtained a B.A. in Physics and Mathematics with highest distinction in 1963, an M.S. in Astronomy in 1965 and a Ph.D. in Physics in 1967, all three degrees from the University of Iowa. He participated in the NASA graduate traineeship from 1962 to 1966 and, at the same time, between 1965 and 1966, he was a visiting student at the Institute of Astrophysics at the University of Kyoto and in the Department of Astronomy at the University of Tokyo. He then began work at the Goddard Institute for Space Studies in 1967. Career After graduate school, Hansen continued his work with radiative transfer models, attempting to understand the Venusian atmosphere. He later applied and refined these models to understand the Earth's atmosphere, and in particular, the effects that aerosols and trace gases have on Earth's climate. His development and use of global climate models has contributed to the further understanding of the Earth's climate. In 2009 his first book, Storms of My Grandchildren, was published. In 2012 he presented the TED Talk "Why I must speak out about climate change". From 1981 to 2013, he was the director of the NASA Goddard Institute for Space Studies in New York City, a part of the Goddard Space Flight Center. , Hansen directs the Program on Climate Science, Awareness and Solutions at Columbia University's Earth Institute. The program is working to continue to "connect the dots" from advancing basic climate science to promoting public awareness to advocating policy actions. Hansen is representing his granddaughter as well as "future generations" as plaintiffs in the Juliana v. United States lawsuit, which is suing the United States government and