James Hansen

James Edward Hansen (born March 29, 1941) is an American climatologist. He is an adjunct professor directing the Program on Climate Science, Awareness and Solutions 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. In 2000, Hansen had proposed an alternative scenario for combating the threat of global warming by focusing on reducing non-CO2 greenhouse gases (GHGs). His estimates of global climate had found that non-CO2 GHGs (such as methane) caused more observed global warming than carbon dioxide. However, he pointed out that CO2 would become the dominant climate forcing, if global emissions continued to rise.