In this episode of This Green Earth hosts Nell and Chris will be talking with (01:55) Dave Goulson. Goulson is a Professor of Biology at University of Sussex who has published more than 300 scientific articles on the ecology and conservation of bumblebees and other insects. He has just released a new book called "Silent Earth - Averting the Insect Apocalypse." Goulson will share more on the dramatic decline of insect species and how this can directly impact all life on Earth.Then (25:23) Dr. John Francis a.k.a. the “Planetwalker” comes on the show. Francis is an author and environmental professor. His environmental work began in 1971, when he witnessed an oil spill in San Francisco Bay. It was then that he gave up the use of motorized vehicles and began to walk. He then went on to create the nonprofit Planetwalk, an environmental awareness organization, took a vow of silence for 17 years, and received multiple degrees, including a PhD in Land Resources.