Earth Day is turning 50 and I talk with Dr. Arlene Blum, who exemplifies the energy, humanity and spirit of this celebration which began in 1970 and gave birth to the modern environmental movement. Arlene is a biophysical chemist, an author, a mountaineer and Executive Director of the Green Science Policy Institute. Arlene’s belief that we can all do seemingly impossible things - is the foundation to a life of adventure.