Parts of Australia’s iconic reef have just suffered their worst annual decline since records began almost 40 years ago. After years of recovery, back-to-back climate stressors have driven a sharp drop in coral cover – the percentage of a reef’s surface covered in live coral – across its three regions.

Mike Emslie, who heads the tropical marine research agency’s long-term monitoring program, said the live coral cover measured in 2024 was the largest recorded in 39 years of surveys.

Reefs have been battered by cyclones and starfish that eat coral, but heat stress driven by climate change is the main cause of damage.