This week, we're airing a series of interviews called Bearing Witness: Voices of Climate Change. They're stories told by longtime Arizonans about changes they've seen in the familiar landscapes of their lives. While personal experience, in and of itself, is not scientific conclusion, many researchers believe long-term observation is a critical component to understanding how climate change affects humanity and the planet. Today's interview is with teacher, author and ecologist, Gary Nabhan. He is the founding director of Northern Arizona University's Center for SUstainable Environments, and currently teaches at the University of Arizona in Tucson. Nabhan is also a farmer of indigenous foods in the desert of Patagonia, Arizona. A pioneer of local food and heirloom seed movements, he connects food supply to culture, ecology and poverty. Nabhan is now documenting stories of 'climate refugees': the most marginalized people affected by climate change.