Most Great Barrier Reef corals studied this year were bleached

CANBERRA, Australia (AP) — 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, scientists at the australian government.

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 temperatures in the Pacific Ocean, the Great Barrier Reef Marine Authority said in a statement. its annual report released Tuesday night found that 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 will not be very high,” Wachenfeld said 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.

Simon Bradshaw, a research fellow at the Climate Council, an Australia-based group that tracks climate change, said the report showed the reef’s survival depended on deep global emissions cuts in the decade.

“This is heartbreaking. This is deeply concerning,” Bradshaw said. “It shows that our Barrier Reef really is in very serious trouble.”

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 garnered enough international support to postpone an attempt by UNESCO, the United Nations cultural organization, to downgrade the reef’s World Heritage status to “endangered” due to damage caused by climate change.

But the question will be back on the World Heritage Committee’s agenda at its next annual meeting.

The Great Barrier Reef represents about 10% of the world’s coral reef ecosystems and was named for the great dangers it posed to seafarers in the 18th century. The network of more than 2,500 reefs covers 348,000 square kilometers (134,000 square miles).

Coral is made up of tiny animals called polyps that feed on microscopic algae that live inside reefs and are sensitive to changes in water temperature.

The algae provide the reefs with their kaleidoscope of colors and produce sugars through photosynthesis that provide the coral with most of its nutrients.

Rising ocean temperatures convert the chemicals produced by the algae into toxins. The coral turns white as it effectively spits out the poisonous algae.

Heat stress beyond a few weeks can starve coral.

The latest whitewash is an unwelcome reminder of the differences in climate change policy between Australian politicians.

The Conservative government, which is seeking re-election on May 21, has less ambitious emissions reduction targets than the centre-left opposition promises.

Prime Minister Scott Morrison’s Liberal Party aims to cut Australia’s emissions 26-28% below 2005 levels by 2030.

The opposition Labor Party has promised to cut emissions by 43% by the end of the decade.

Morrison was widely criticized at the UN climate conference last November for not setting a more ambitious target.

Environmental group Greenpeace Australia Pacific said in a statement that the extent of the latest bleaching was “another damning indictment of the Morrison government, which has failed to protect the reef and has exacerbated the problem through its support of fossil fuels.”


This story corrects that the annual meeting of the World Heritage Committee has been postponed and will not take place next month.

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