WATCH: Nat Geo’s ‘Moment on the Earth’ features polar bear mom and cub

National Geographic captures a tender moment between a polar bear mother and her cub in a photo by Martin Gregus Jr., as they wait for sea ice to return.

​National Geographic captures a tender moment between a polar bear mother and her cub in a photo by Martin Gregus Jr., as they wait for sea ice to return.  GMA National Geographic captures a tender moment between a polar bear mother and her cub in a photo by Martin Gregus Jr., as they wait for sea ice to return.