The Great Barrier Reef has been experiencing the worst bleaching event of its history, turning the coloured corals into ghostly white. This phenomenon occurs when the ocean stays at higher than normal temperatures, causing the corals to expel the algae, zooxanthellae, that live on them. Losing this algae puts stress on the coral and causes it to turn completely white. While it is possible for coral to recover from a bleaching event, the severity and length of the bleaching determines whether the coral will recover or die. It is estimated that up to 50% of the currently bleached coral will die.
As the globe continues to warm and ocean temperatures increase, we bleaching events like this will become more frequent and could occur annually as soon as 2030.