Overview

• State and federal scientists have confirmed the heatwave killed coral along a 1,500 km stretch of Western Australia’s tropical reefs, with site-specific mortality ranging from 11 percent to over 90 percent.
• Surveys presented in Perth show Degree Heating Weeks reached between 15 and 30 at most sites, far exceeding the 8 DHW threshold typically linked to mass coral deaths.
• Previously resilient systems such as the Rowley Shoals recorded 61–90 percent mortality at Mermaid and Clerke reefs, while Ningaloo Reef experienced 31–60 percent bleaching and death.
• Researchers attribute the event primarily to anthropogenic ocean warming—occurring without a La Niña and alongside the warmest sea surface temperatures on record—and place it within the ongoing global bleaching crisis.
• At the multi-agency meeting, scientists warned that reefs need 10–15 years to recover but face increasingly narrow recovery windows, calling for enhanced local protections, coordinated monitoring and deeper emissions reductions.