Almost one-fifth of all carbon emissions in the world come from the transportation sector, but society finds itself at a fork in the road: embrace shared, autonomous, electric vehicles, or continue with privately-owned, gasoline-powered vehicles. Founder and Chief Scientist Jeffery Greenblatt talks with Ty Burrell in "The Road Ahead" from the #YEARSproject created by National Geographic. Check it out on the new Facebook Watch platform!