It’s said that water is life and trying to control and store water through massive dam projects has been a way of life for a long time, especially in the western U.S.  
But it turns out dams emit greenhouse gas and can have environmental impacts. Just how much do they emit and why are some rivers better off left to flow naturally? 
Stephen Hawley, author of Cracked: The Future of Dams in a Hot, Chaotic World, discusses what a world without dams could bring.