James Hansen
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 an activist for action to mitigate the effects of climate change, which on a few occasions has led to his arrest. After graduate school, Hansen continued his work with radiative transfer models, attempting to understand the Venusian atmosphere. Later he applied and refined these models to understand the Earth's atmosphere, in particular, the effects that aerosols and trace gases have on Earth's climate. Hansen's 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 a 2012 TED Talk: Why I must speak out about climate change. From 1981 to 2013, he was the head of the NASA Goddard Institute for Space Studies in New York City, a part of the Goddard Space Flight Center in Greenbelt, Maryland. He currently 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.