John Francis was in his 20s when a 1971 oil spill in San Francisco Bay jarred his comfortable life. Even as he joined the volunteers who scrubbed the beaches and fought to save birds and sea creatures poisoned by petroleum, he felt the need to make a deeper, more personal commitment. So he took a vow of silence that would last 17 years. In 2008, National Geographic published Francis's stirring memoir "Planetwalker: 22 Years of Walking; 17 Years of Silence." To share his insights with others, Francis founded 'Planetwalk,' a non-profit organization dedicated to raising environmental consciousness and promoting Earth stewardship. John was UNEP goodwill ambassador to the world's grassroots communities. Planetwalk's work fosters communication and research between young people, scientists, and environmental practitioners through a global network and educational programs. In 2010, Francis became the first National Geographic Education Fellow.