Pittsburgh Post-Gazette: Climate change is at the heart of Showtime's nine-part docuseries "Years of Living Dangerously" (10 p.m. Sunday), which features an assortment of celebrities focusing on one particular aspect of climate change. Actor and former California Gov. Arnold Schwarzenegger is among the executive producers of the series, and he also hosts a segment along with actors Don Cheadle, Jessica Alba, Harrison Ford, Matt Damon, Michael C. Hall and journalist Lesley Stahl. The first episode of the show is available...