CANBERRA, Australia — More than 90% of the Great Barrier Reef coral examined this year bleached in the fourth such massive event in seven years on the world’s largest coral reef ecosystem, Australian government scientists said.
The bleaching is caused by global warming, but this is the reef’s first bleaching event during a La Niña weather pattern, which is associated with cooler Pacific Ocean temperatures, the Great Barrier Reef Marine Authority said in its report. annual report released Tuesday night that found 91% of areas surveyed were affected.
Bleaching in 2016, 2017 and 2020 damaged two-thirds of the coral on the famous reef off Australia’s east coast.
Coral bleaches in response to heat stress and scientists expect most coral to recover from the current event, said David Wachenfeld, chief scientist for the authority, which manages the reef’s ecosystem.
“Early indications are that mortality is not going to be very high,” Wachenfeld told the Australian Broadcasting Corp. on Wednesday.
“We expect to see most of the bleached coral recover and we will end up with an event more like 2020 when, yes, there was mass bleaching, but there was low mortality,” Wachenfeld added.
Bleaching events in 2016 and 2017 led to “pretty high levels of coral mortality,” Wachenfeld said.
Last December, the first month of the southern hemisphere’s summer, was the hottest December the reef had experienced since 1900. A “marine heat wave” had set in at the end of February, according to the report.
A United Nations delegation visited the reef in March to assess whether the reef’s World Heritage listing should be downgraded due to the ravages of climate change.
In July last year, Australia gained enough international support to defer an attempt by UNESCO, the United Nations cultural organization, to downgrade the reef’s status as a World Heritage Site to “endangered” due to damage caused by the change. climate.
But the question will be back on the World Heritage Committee’s agenda at its annual meeting next month.