By Newsbreak Producer Matthew Veeran - The Great Barrier Reef has suffered its largest annual decline in coral cover since records began almost 40 years ago - following the most widespread bleaching event on record. A new report by the Australian Institute of Marine Science found that heat stress from climate change is the primary cause, with the reef's northern and southern sections the most affected. Scientists warn the iconic Australian habitat may be reaching a "tipping point" where coral cannot recover fast enough between catastrophic events. Mattthew found out more in this week's Greenscene...