The Great Barrier Reef is experiencing a new episode of “widespread” bleaching due to high temperatures in northeastern Australia’s waters that threaten this World Heritage Site, officials said on Friday.
“Bleaching was detected off the Marine Park. It is widespread but variable across multiple regions, ranging from minor to severe impact,” said the Great Barrier Reef Marine Park Authority.
Last week, temperatures in this area were between 0.5°C and 2°C above the median. In some areas further north, or near the coast, temperatures were 2°C to 4°C above normal.
“The most heavily impacted reefs are found near the Townsville region. There have also been reports of early mortality where heat stress was greatest,” the agency noted.
The news comes before a trip by representatives of the United Nations Educational, Scientific and Cultural Organization (Unesco) to the reef, to inspect the health of this 2,300 kilometer long ecosystem. Months ago, the UN agency threatened to classify it as an endangered heritage.
The bleaching phenomenon is caused by the thermal stress of corals due to rising temperatures. This increase causes them to expel the algae that live in their tissues and that give them their characteristic bright colors. Since 1997, there have been five such episodes.
In addition, the Great Barrier Reef has been hit by extreme cyclones and outbreaks of coral-eating purple acanthaster starfish.
While these changes are not yet classified as a mass bleaching phenomenon, the Society for the Australian Marine Conservation has classified them as “disastrous news”.
“This shows the consistent pressure under which our reef meets with global warming,” said its campaign director Lissa Schindler.
“A healthy reef can recover from coral bleaching, but it takes time. More frequent heat waves (…) means it doesn’t have that kind of weather,” he added.
Earlier this year, the Conservative Australian government announced a $700 million program to protect the Great Barrier Reef and prevent it from being removed from the UNESCO World Heritage List.
At the same time, however, the Executive is accused by environmental organizations of not acting with sufficient conviction to reduce greenhouse gas emissions in the country, one of the world’s largest exporters of gas and coal.
