The Great Barrier Reef, the world's largest coral reef system, has lost more than half of its coral in the past 25 years. That’s according to a new report from the Australian Research Council’s Centre of Excellence for Coral Reef Studies, published this week, which found that mass bleaching events are irreversibly devastating small, medium and large coral populations along the 2,300 kilometre length of the reef. “Coral colony abundances on reef crests and slopes have declined sharply across all colony size classes and in all coral taxa compared to historical baselines,” the report states. \"We can clearly correlate the rising temperatures to coral mortality and bleaching on the Great Barrier Reef,” he told the ABC. “We've had large-scale bleaching events in 1998 and 2002, but they were absolutely dwarfed by the more recent ones in 2016 and 2017.