@cbsnews: Parts of the Great Barrier Reef are dying at a record rate as banks of once-vibrant corals turn into a sickly shade of white. “It can’t get repeatedly hammered like this,” WWF-Australia’s head of oceans said. “We are fast approaching a tipping point.” #greatbarrierreef #australia #coral #coralreef #coralbleaching #environment #worldheritagesite #globalwarming #climatechange #ocean