Sign up for the MSNBC newsletter
You have been successfully added to our newsletter.
Let our news meet your inbox
Scientists even more confident climate change is real
The latest UN report lays to rest the lingering doubts about climate change. So why are the global warming deniers still at it? What's in it for them to keep denying what's obvious to the scientists? Republican strategist Chip Saltsman and Penn State Professor of Meteorology Michael Mann discuss with Hardball’s Chris Matthews.