Massive quake triggers tsunami warnings; EPA proposes climate regulation rollback

One of the most powerful earthquakes ever recorded struck the east coast of Russia, triggering tsunami warnings across the Pacific. NBC News meteorologist Bill Karins joins guest host Andrea Mitchell to explain the science behind the quake. And University of Pennsylvania climate scientist Dr. Michael Mann joins to discuss the Environmental Protection Agency proposal to repeal the “endangerment finding.” It’s a 2009 rule that determined that greenhouse gases like carbon dioxide endanger public health and welfare.