Weekend TV watch

Where will the power come from? The second season of the Arnold Schwarzenegger-produced climate change documentary series “Years of Living Dangerously” (Sunday at 8 p.m. on National Geographic Channel) opens with David Letterman traveling to India to investigate the struggle to bring electricity to rural villages. “Saturday Night Live’s” Cecily Strong visits Florida and Nevada to find out what’s blocking the growth of solar energy. Correspondents for the upcoming season include Don Cheadle, Jack Black, Gisele Bundchen and Schwarzenegger himself. Stick around: At 9 p.m., the network airs Leonardo DiCaprio’s climate change documentary “Before the Flood.” The Oscar winner crosses the globe in search of solutions to help the environment.

Bill Murray is celebrated by such pals as Aziz Ansari, Dan Aykroyd, Jimmy Kimmel and Sigourney Weaver on PBS’ “Bill Murray: The Mark Twain Prize” (tonight at 9 on WGBH, Ch. 2). Murray is the 19th recipient of the Kennedy Center Mark Twain Prize for American Humor.

It doesn’t look a day over 90. CBS’ “Elementary” (Sunday at 10 p.m. on WBZ, Ch. 4) celebrates its 100th episode with Holmes and Watson investigating the murder of a financial analyst. Call me crazy, but I think they’ll solve this crime.

Get into the holiday spirit with Decades’ epic marathon of the classic cult gothic soap opera “Dark Shadows” (starting at 1 p.m. tomorrow and running through Monday morning). It’s the charming story of a vampire who awakens from a 175-year sleep to search for new blood and the reincarnation of his lost love.