Waving a white flag - what message does coral bleaching on the Great Barrier Reef send?

https://www.youtube.com/watch?v=AkFev-vWo7U
27 June 2017

Coral bleaching indicates that a reef is under stress. Australia’s Great Barrier Reef has experienced an increased rate of bleaching events in recent years. Dr Jennie Mallela and Dr Sophie Lewis have combined biological data with climate data to provide a clearer understanding of what has caused these events.