Most Great Barrier Reef corals surveyed this year have been bleached
More than 90% of Great Barrier Reef corals surveyed this year were bleached in the fourth mass event in seven years in the world’s largest coral reef ecosystem, Australian government scientists have said.
The bleaching is caused by global warming, but this is the reef’s first bleaching event during a La Nina weather pattern, which is associated with cooler Pacific Ocean temperatures, the Great Barrier Reef said. Marine Authority in its annual report released on Tuesday evening, which found that 91% of surveyed areas were affected.
Bleaching in 2016, 2017 and 2020 damaged two-thirds of the corals in the famed reef off the east coast of Australia.
“Early indications are that mortality will not be very high,” Wachenfeld said Wednesday.
“Hopefully we’ll see most of the bleached corals recover and we’ll end up with an event a bit more like 2020 when, yes, there was massive bleaching, but there was low mortality.”
The 2016 and 2017 bleaching events resulted in “pretty high levels of coral mortality,” Wachenfeld said.
Simon Bradshaw, a researcher at the Climate Council, an Australia-based group that tracks climate change, said the report shows the reef’s survival depends on deep reductions in global emissions over the decade.
“It’s heartbreaking. It’s deeply disturbing,” Mr Bradshaw said.
Last December, the first month of Southern Hemisphere summer, was the warmest December the reef has seen since 1900.
A “marine heat wave” had set in by late February, the report said.
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.
Last July, Australia garnered enough international support to defer an attempt by Unesco, the United Nations’ cultural organization, to downgrade the reef’s World Heritage status to “endangered” due to damage from climate change.
But the issue will be back on the agenda of the World Heritage Committee at its annual meeting next month.
The network of over 2,500 reefs covers 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.
Algae give the reefs their kaleidoscope of colors and produce sugars through photosynthesis that provide the coral with most of its nutrients.
Rising ocean temperatures turn chemicals produced by algae into toxins.
The coral turns white as it effectively spits out toxic algae.
The latest whitewash is an unwelcome reminder of the policy differences on climate change among Australian politicians.
The Conservative government 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 by 26-28% below 2005 levels by 2030.
The opposition Labor Party has promised to cut emissions by 43% by the end of the decade.
Mr Morrison was widely criticized at the UN climate conference last November for failing to set a more ambitious target.
Environmental group Greenpeace Australia Pacific said in a statement that the scale of the latest bleaching is “another damning indictment of the Morrison government, which has failed to protect the reef and has exacerbated the problem by backing fuels fossils”.