Great Barrier Reef encounters record‑widespread bleaching.

Great Barrier Reef Faces Record‑Spanning Bleaching Crisis

Scientists have documented the most spatially extensive coral bleaching event since monitoring began, driven by sweltering ocean temperatures in 2024‑25.

Key Findings from the Australian Institute of Marine Science

• Bleaching covered 124 reefs surveyed between August 2024 and May 2025.
• Both northern and southern sections of the reef experienced the largest annual decline in coral cover ever recorded.
• Reefs were battered by tropical cyclones and crown‑of‑thorns starfish infestations, but the primary cause remains climate change.
• Acropora, a rapidly growing coral type, suffered the most severe bleaching.

Heat Stress and Long‑Term Recovery

The report revealed unprecedented levels of heat stress, the sixth such event in nine years, causing the most severe bleaching on record. Bleaching occurs when water temperatures rise, forcing corals to expel their colorful zooxanthellae algae. Persistent high temperatures can turn corals white and ultimately lead to death.

Mike Emslie, research lead at the institute, emphasized that past coral growth could cushion record losses but the reef remains an “amazing place” worth fighting for. He added that recovery could take years and depends on future coral reproduction and minimal environmental disturbance.

World Wildlife Fund Concerns

Richard Leck compared the reef’s fluctuating health to a rollercoaster, describing it as a sign of an ecosystem under immense stress. He warned that some coral reefs worldwide are already beyond recovery, and the Great Barrier Reef could follow the same fate without ambitious and rapid climate action.

Global Context and Climate Targets

Australia’s average sea surface temperature in 2024 was the highest on record according to the Australian National University. The country is developing its next round of emissions reduction targets under the Paris Climate Agreement, a key obligation that could help mitigate the reef’s distress. Meanwhile, Australia remains one of the world’s biggest coal exporters, heavily subsidizing fossil fuel sectors.