A six-part celebration of the natural world features children's thoughts on the environment, endangered animals and climate change. Also: readings by Alan Cumming, Tina Fey, Liam Neeson, Susan Sarandon, Neil deGrasse Tyson and Jeffrey Wright; performances by Ziggy Marley, Elizabeth Mitchell, Willie Nelson, Karen O and They Might Be Giants; remarks by scientists from the American Museum of Natural History.