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‘Devastating’: 91% of reefs surveyed on Great Barrier Reef affected by coral bleaching in 2022 | Great Barrier Reef

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Coral bleaching has affected 91% of surveyed reefs along the Great Barrier Reef this year, according to a report by government scientists which confirms the natural landmark has suffered its sixth mass bleaching event on record.

The Reef Snapshot: Summer 2021-22, quietly released by the Great Barrier Reef Marine Park Authority on Tuesday evening after weeks of delay, said above-average water temperatures at the end of summer had caused coral bleaching throughout the 2,300 km reef system, but particularly in the central region between Cape Tribulation and the Whitsundays.

“Surveys confirm a massive bleaching event, with coral bleaching observed on multiple reefs across all regions,” a statement accompanying the report said. “This is the fourth mass bleaching event since 2016 and the sixth to occur on the Great Barrier Reef since 1998.”

This was the first recorded mass bleaching event in a cooler La Niña year.

Scientists from the Marine Park Authority and the Australian Institute of Marine Science studied 719 shallow-water reefs between the Torres Strait and the Capricorn Bunker Group at the southern end of the reef system, mostly east help from helicopters. They found that 654 reefs showed some bleaching.

Map of observations from the 2022 aerial survey of coral bleaching of the reef community across the Great Barrier Reef following the last heat wave March 12-23, 2022
More than 90% of surveyed reefs along the Great Barrier Reef were affected by coral bleaching in 2022. Photograph: Great Barrier Reef Marine Park Authority
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A map released with the report shows the worst and most extreme bleaching has occurred in the region that covers the areas most visited by tourists. The report says inshore and offshore reefs have been badly affected.

Marine park authority scientists were not available to comment on the report on Tuesday evening. The authority’s chief scientist, Dr David Wachenfeld, told the Guardian in March that the bleaching was not expected in a La Niña.

“But that said, the climate is changing and the planet and the reef are about 1.5 degrees centigrade warmer than they were 150 years ago,” he said. “Because of this, the weather is changing. Unexpected events are now to be expected. Nothing surprises me anymore. »

Lissa Schindler, campaign manager at the Australian Marine Conservation Society, said the report was “devastating news for anyone who loves the reef” and “further evidence” that cutting fossil fuel emissions should be the top priority of the next Australian government.

“It was a La Nina year, normally characterized by more cloud cover and rain,” she said. “It should have been a welcome reprieve for our reef to help it recover and yet the snapshot shows that over 90% of the reefs surveyed had some bleaching.

“Although bleaching is becoming more and more frequent, it is not normal and we must not accept that it is so. We must break the norms that break our reef.

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Schindler said that while Labor had pledged to cut emissions more by 2030 than the coalition, neither party had targets in line with what would be needed globally to save the reef.

The Intergovernmental Panel on Climate Change has found that limiting global warming to 1.5C rather than 2C is likely to be the difference between the survival of some tropical reef corals and their complete decline. A report by Climate Analytics found that the Coalition’s 2030 emissions reduction target was in line with more than 3C of heating and the Labor Party’s target was around 2C.

Climate Council research director Dr Simon Bradshaw said: “This is a problem that cannot be solved with big, shiny funding announcements. The science is very clear: in order to save the world’s reefs from total destruction, we need to drastically reduce emissions in the 2020s.”

Scientists began sounding the alarm for this year’s bleaching event in December, when ocean temperatures above the reef reached a record high for that month.

Bleaching occurs when coral is stressed by above average water temperatures. The coral animal expels the photosynthetic algae that inhabit it and provides the coral with its food and color.

Chart

Corals can survive bleaching events. Scientists plan to carry out in-water checks to see how many corals have survived and regained their algae and color by the end of the year.

Studies have shown that heat stress can have several “sub-lethal” effects on corals, including making them more susceptible to disease, slowing their growth, and limiting their ability to reproduce.

The results of the investigations are expected to inform a report by a United Nations mission that visited the reef in March to check on its health and management. Scientists from Unesco and the International Union for Conservation of Nature were briefed on the investigations during the 10-day monitoring trip. Their report is expected before the next World Heritage meeting, currently scheduled for June.

Last year, Unesco scientific advisers recommended that the reef be placed on a list of “in danger” World Heritage sites due to the impact of the climate crisis and the slow progress in the improvement of water quality. Sustained lobbying by the Morrison government led the 21-country committee to go against this advice.

The release of the report and maps follows a call from scientists and conservationists for the Marine Authority to make them public. SBS reported that Paul Hardisty, the chief executive of the Australian Marine Institute of Science, told a staff meeting that the Prime Minister’s Department and Cabinet had advised that the survey results be released during the federal election campaign, which would have violated gatekeeper conventions.

Environmental campaigners have also called on the government to publish the State of the Environment Report, a five-year national assessment that has sat with Environment Minister Sussan Ley since December.

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