A teenager got a hero's send-off as she set off on a mission to promote environmentalism. Greta Thunberg, 16, of Sweden has been making waves even before this planned boat trip. The young activist has traveled all over the world talking about the urgency for world leaders to act on climate change before it's too late. She knows the obstacles she faces, but they're not stopping her. She boarded a zero-carbon yacht in the United Kingdom bound for the United States. InsideEdition.com's Mara Montalbano has more.