James Balog, a National Geographic photographer and climate expert, will speak at 7 p.m. April 3 at Drake University's Knapp Center as part of the Martin Bucksbaum Distinguished Lecture Series. As a complement to Balog's lecture, two screenings of the film "Chasing Ice" will be offered at 7 p.m. April 6 and April 7 at Sussman Theater in Drake's Olmsted Center. These screenings are free and open to the public. No ticket is required.