This week on Sierra Club Radio: 1) The Mayor of Los Angeles, Antonio Villaraigosa, talks with us about his pledge for a coal-free Los Angeles, and his vision for making L.A. the greenest city in the country 2) Eric Simons on his new book Darwin Slept Here: Discovery, Adventure, and Swimming Iguanas in Charles Darwin's South America 3) Annie Somerville, Executive Chef at Greens Restaurant in San Francisco, gives green cuisine tips.