Heat stress from climate change is identified as the primary cause of mass bleaching, worsened by factors such as cyclones and crown-of-thorns starfish outbreaks.
Aims found that two of the three areas monitored since 1986 experienced coral losses, marking the largest annual decline recorded.
Researchers warn that the reef faces a "volatile" future and may reach a "point from which it cannot recover" due to the increasing frequency of mass bleaching events.