Humans bringing earth to tipping points

A new article published in the journal Nature warns humans are pushing Earth dangerously close to the brink, and it goes beyond global warming. The paper argues the rapid extinction of species and changes in ocean chemistry may also be nearing points of no return. MPR's Cathy Wurzer spoke with Jon Foley, who directs the University of Minnesota's Institute on the Environment. He was one of more than two dozen scientists who contributed to the research.