World-renowned coral reefs lining Western Australia's coastlines are grappling with the worst bleaching crisis ever documented, as scientists attribute this calamity to the "longest, largest and most intense" marine heatwave the region has faced. The period between last August and this May saw higher water temperatures leading to severe heat stress on the corals. This unprecedented stress resulted in the coral expelling the vital algae that provide them with nourishment and vivid colors in a phenomenon known as bleaching, often resulting in high mortality rates among these coral species.
The consequences of this environmental disaster span over 1,500 kilometers (932 miles) and affect regions that had previously remained largely untouched by the detrimental impacts of climate change. For two consecutive years, coral reefs around the globe have endured significant bleaching, propelled by soaring ocean temperatures. In normal circumstances, eight weeks of elevated heat are enough to lead to coral fatalities, and preliminary assessments suggest that many reefs in Western Australia could have lost between 15 to 30 percent of their coral.
James Gilmour of the Australian Institute of Marine Science (Aims) stated that the combination of duration, intensity, and broad geographic impact of the heat stress experienced in this event is unprecedented for many of the reef systems in the area. Aims' recent report indicates that the coral bleaching observed during the 2024-25 season constitutes "the most severe coral bleaching on record" for Western Australian reefs, impacting both the northwestern and central reef systems.
Historically resilient areas, such as the Rowley Shoals, north Kimberley, and Ningaloo Reef—designated as World Heritage sites—have now been severely affected. This trend is concerning, particularly as the Great Barrier Reef on Australia's eastern coast has also reported its most significant coral decline in nearly four decades. Federal Environment Minister Murray Watt highlighted the critical state of Ningaloo's coral, stressing that it highlights the necessity for immediate action toward achieving net zero emissions both in Australia and worldwide.
Climate change is driving a rise in the frequency and intensity of coral bleaching events, leaving these vital marine ecosystems with insufficient time for recovery, a process that typically spans 10 to 15 years. Dr. Gilmour reiterated that carbon emissions remain the foremost threat to not just Australian reefs, but to coral reefs globally. The UN has previously cautioned that even if global temperatures are limited to a 1.5C increase above pre-industrial levels, a staggering 70 to 90% of the world's tropical coral reefs face extinction.
