Ocean temperatures in the Great Barrier Reef have hit their highest levels in 400 years, warn researchers. This trend threatens the survival of the reef, one of the most diverse coral ecosystems in the world.
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Between 2016 and 2024, the reef experienced severe coral bleaching due to rising water temperatures. Coral bleaching happens when corals expel the algae that give them color and nourishment, often leading to their death. Recent aerial surveys showed that two-thirds of the reef’s shallow areas were affected by bleaching.
Researchers from Melbourne University and other Australian institutions studied coral samples from 1618 to 1995. They also looked at sea surface temperature data from 1900 to 2024. They found that temperatures were stable before 1900 but have been steadily rising since 1960. Extreme heat was noted in 2016, 2017, 2020, 2022, and 2024, with record-high temperatures in January and March
Benjamin Henley, the study’s lead author, stressed the urgent need to address climate change. Without action, the reef may not survive, as frequent heat extremes hinder coral adaptation. The Great Barrier Reef is vital for seafood production and tourism, making its protection crucial.
Globally, reefs face similar threats. Even if global warming stays within the Paris Agreement's goal of 1.5°C (2.7°F), 70% to 90% of corals may still be at risk. Michael McPhaden from NOAA, who wasn’t involved in the study, noted that while corals have adapted in the past, current conditions may be too extreme for even the hardiest corals to survive.
The Great Barrier Reef’s situation serves as a clear warning about climate change’s impact. If trends continue, the loss of coral diversity and reef area could become severe, endangering this important marine ecosystem.
