Climatologist James Hansen - 'We’re already at a level of emergency'

Former NASA scientist Dr. James Hansen is one of the most respected climate scientists in the world. In fact he's famous for helping first-bring the issue of climate change to wide-spread public attention way back in 1988 when he testified in-front of congress to alert senators that the greenhouse gas effect was real, and that we were already starting to see its impacts on the climate. We caught up with Dr. Hansen at COP 21 to speak with him about what the world needs to do to act on climate, and why when it comes to global warming "we’re already at a level of emergency."