Mountainfilm audiences are familiar with James Balog because he has exhibited his striking portraits of animals and trees in Telluride. He returns with important work from his “Extreme Ice Survey,” which documents how glaciers around the world are receding. Balog was featured recently on an outstanding NOVA program on PBS and also received a prestigious award from the Aspen Institute for visual art and design. He will speak about his work on Sunday at 10:00 a.m. at the Sheridan Opera House.