April 22 is Earth Day, and TV networks are marking the occasion with a variety of programs about the planet and its natural resources.

NBCUniversal's sixth annual slate of "Green is Universal" programming across its broadcast and cable networks will include a week of "Today" segments including an eco-chic fashion show, sustainable beauty products, green entertaining, eco gear/gadgets, a look at the garbage and recycling process in major cities, and a "living wall" made of herbs. CNBC's "Squawk on the Street" will report on green transportation, and "Rock Center with Brian Williams" will investigate oil exploration's threat to the Amazon rain forest. "Nightly News" will report on the Oil Sands and the environmental effects of extracting and transporting oil, and "The Tonight Show," "Late Night With Jimmy Fallon," and Last Call with Carson Daly" will all include segments with a green theme.

Bravo and Syfy will feature eco-themed episodes throughout Earth Week, and among the Weather Channel's scheduled segments is a report from the Global Leaders Summit in Costa Rica. 14 new green-themed The More You Know public service announcements will premiere during Earth Week that will feature such celebrities as Alison Sweeney, Brian Williams, and Ken Jeong giving tips on reducing and recycling, saving energy and water, carpooling, paying bills online, and carrying reusable shopping bags.

Green is Universal will also launch "Share and Tell," an online recycling campaign which encourages sharing and trading of unwanted goods via social media. NBCUniversal shows and talent are contributing items that fans can win by entering sweepstakes on Facebook.

As part of its "Green it. Mean it." campaign, Fox has enlisted its talent for a series of eco-tips that will run during its programs. Martha Plimpton of "Raising Hope" talks about recycling newspapers, Matt Morrison from "Glee" advises watering your lawn early in the morning, and "The Following's" Kevin Bacon suggests washing clothes in cold water, to name a few.

If you missed them in theaters, you can catch several acclaimed documentaries. "Chasing Ice," which dramatically depict disappearing glaciers, airing April 19 at 8 p.m. ET/PT on National Geographic Channel; and "The Island President," about the Maldives' former leader's efforts to save his tropical island nation for the effects of global warming, premiering on PBS' "Independent Lens" on April 22 at 10 p.m. ET/PT.

Which endangered species would you save from extinction? Pandas and polar bears? Naturalist David Attenborough has his own top 10 list that includes black lions, tamarins, and Sumatran rhinos, and he explains why in the Nat Geo Wild special "Attenborough's Ark," premiering April 21 at 8 p.m. ET/PT.

Elephants are considered vulnerable or endangered due to poaching and habitat destruction and could be at risk for extinction within the next ten years. That's according to "An Apology to Elephants," which depicts man's inhumanity to pachyderm and what we need to do to change that. "The first thing we need to know is that the elephants need our help," says producer ad narrator Lily Tomlin, a longtime elephant advocate. It premieres April 22 at 7 p.m. ET/PT on HBO.

Photo: Justin Stephens/NBC

TV shows celebrates Earth Day
Your guide to the holiday's planet-centric programs.