Storms, Starfish Wiped out Half of Great Barrier Reef Coral

A new study finds that in the last 27 years, half of Australia's Great Barrier Reef coral has died. Gwen Ifill talks to Nancy Knowlton, a coral reef biologist and chair of Marine Science at the Smithsonian Institution, about ecological and economical consequences of the collapse, as well as measures to help mediate the decline.