Rising ocean temperatures threaten Great Barrier Reef: study reveals warmest conditions in 400 years
Water temperatures in and around Australia’s Great Barrier Reef have surged to their highest levels in 400 years over the past decade, placing the world’s largest reef under severe threat, according to new research published Thursday.
The Great Barrier Reef, spanning approximately 1,500 miles (2,400 km) off Queensland’s northern coast, has long been celebrated as the largest living ecosystem on the planet. This latest study offers a rare historical perspective on the impact of man-made climate change, contrasting with previous research that typically focuses on more recent data.
Researchers from Australian universities examined coral samples, akin to counting tree rings, to reconstruct ocean temperatures back to 1618. Combined with modern ship and satellite data, the study reveals a stable temperature trend for centuries that began rising from 1900 onward due to human activity. From 1960 to 2024, temperatures during the key summer months of January to March have increased at an average rate of 0.12°C (0.22°F) per decade.
Since 2016, the reef has endured five instances of mass coral bleaching, a phenomenon where heat stress causes coral to expel the algae living within it, turning the coral white and increasing its risk of death. These bleaching events occurred during five of the six warmest years in the past 400 years, underscoring the reef’s current vulnerability.
“The world is losing one of its icons,” said Benjamin Henley, an academic at the University of Melbourne and a co-author of the study. “It’s hard to understand how that can happen on our watch in our lifetime. So it’s very, very sad.”
The latest data point, covering January to March of this year, was the highest on record, far exceeding previous measurements. Coral reefs, which serve as crucial barriers against shoreline erosion, host thousands of fish species, and support significant tourism revenue, are now under increased threat globally. According to the U.S. National Oceanic and Atmospheric Administration (NOAA), at least 54 countries and regions have faced mass bleaching since February 2023 due to rising ocean temperatures.
While the Great Barrier Reef is not currently listed as a site in danger by UNESCO, there are recommendations for its inclusion. Australia has actively worked to keep the reef off the endangered list, citing potential economic impacts on its A$6.4 billion ($4.2 billion) tourism industry.
Lissa Schindler, Great Barrier Reef campaign manager at the Australian Marine Conservation Society, emphasized the need for urgent action. “Australia must increase its ambition, action, and commitments to battle climate change and protect our greatest natural asset,” she said.
