Apr 17, 2024 - Science

Great Barrier Reef faces historic bleaching from "perfect storm of threats"

In this underwater photo taken on April 5, 2024, marine biologist Anne Hoggett snorkels to inspect and record bleached and dead coral around Lizard Island on the Great Barrier Reef, located 270 kilometres (167 miles) north of the city of Cairns earlier this month.

In this underwater photo taken on April 5, a marine biologist inspects and records bleached and dead coral around Lizard Island on the Great Barrier Reef, 167 miles north of the Queensland city of Cairns in Australia. Photo: David Gray/AFP via Getty Images

Australia's Great Barrier Reef has been hit by a major bleaching event affecting 73% of the iconic ecosystem, according to a new Australian government report.

The big picture: A "perfect storm of threats" including climate change and the related hottest year on record in 2023 and warmer ocean temperatures, coupled with El Niño, contributed to the bleaching, said Anna Marsden, managing director of the Great Barrier Reef Foundation nonprofit, in a Wednesday interview.

Why it matters: The reports indicate that global warming's ocean impact is worsening.

  • At stake is the fate of everything from the health of national economies to the availability of experimental treatments for cancer, per Axios' senior climate reporter Andrew Freedman.

Threat level: The fifth mass bleaching event to hit the Great Barrier Reef since 2016 has the potential to be the worst on record, according to the report.

  • The situation during the 2023−24 summer has been exacerbated by outbreaks of the coral-eating crown-of-thorns starfish in the world's largest coral reef ecosystem that stretches some 1,429 miles, said Marsden in a video interview.

By the numbers: Australian researchers conducted aerial surveys of 1,080 reefs in the world heritage site and found 39% of these had experienced very high (61-90% coral cover bleached) or extreme (over 90%) levels of bleaching.

State of play: Marsden said that scientists and other groups working to protect the reef were in a "stronger position" than in 2016-17 due to better knowledge and preparatory programs developed in response to what was the reef's worst bleaching on record.

  • "The three levers that we are keeping an eye on are climate change mitigation, coral protection, and then coral restoration — and the coral protection and coral restoration are very much the focus of the conservation community right now," said Marsden.
  • "There are vital reefs that are identified from their biodiversity value or their tourism sites, and we have human divers out there patrolling those sites and killing crown-of-thorns starfish," added Marsden, who noted that a major research program was helping detect the pests faster so teams could respond quicker to outbreaks.
  • No-fishing zones in the reef are helping marine life, while researchers work on helping corals adapt and regrow.

Zoom in: Bob Muir, a Woppaburra people elder who works as an Indigenous partnership coordinator with the Australian Institute of Marine Science on reef restoration and adaptation projects, said the first Australians had carried out key work harvesting coral spawn to replenish reefs.

  • "Men go out and do the harvesting. Then after cryopreservation, the women go and release the eggs into the ocean," he told Axios via email Wednesday.
  • Meanwhile, Marsden noted that the Australian government was investing $1.2 billion to 2030 in increasing the protection efforts, while the Great Barrier Reef Foundation had raised about $358 million in private support.

The bottom line: "We are not at last rites. We have a ... beloved ecosystem that is facing immense challenges but there are solutions and response actions that we can make," Marsden said.

  • Marsden said the reef is the "Amazon rainforest of the sea" and bleaching in this living organism had a "domino effect" on fish, turtles and other animals that depend on it, but "on our watch, we will do everything in our power to make sure she survives this century."

Read the report in full, via DocumentCloud:

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