Ninety-one percent of Australia's Great Barrier Reef whitened in sixth mass bleaching event: study

Australia's Great Barrier Reef has suffered through its sixth mass bleaching event and it was caused entirely by warming ocean waters due to anthropomorphic climate change.

A study published on Tuesday night by the Great Barrier Reef Marine Park Authority and the Australian Institute of Marine Science, Reef Snapshot: summer 2021-22, discovered that last year's La Niña pattern, which typically lowers sea surface temperatures in the Pacific, did not diminish the damage inflicted upon the world's largest reef.

"The Great Barrier Reef’s waters warmed early in December 2021, the hottest December on record since 1900, exceeding historical summer maximums that typically occur in the hottest summer months," the agencies, which monitor the Reef's conditions from May to November, say in their study. "Ocean temperatures continued to accumulate heat throughout the summer until early April 2022. This prolonged heat exposure prompted Reef-wide aerial surveys in the second half of March 2022 - specifically to assess the extent of coral bleaching on shallow-water coral communities."

The destruction observed by the Marine Park Authority and Institute of Marine Science through their aerial surveys was devastating. Almost all of the Reef's coral communities – an intricate network of 2,900 small reefs spanning 2,300 kilometers – experienced bleaching over the past year:

• A total of 719 reefs were surveyed from the air between the Torres Strait and the Capricorn Bunker Group in the Great Barrier Reef Marine Park.
• Of these, 654 reefs (91 percent) exhibited some bleaching. Coral bleaching observed from the air was largely consistent with the spatial distribution of heat stress accumulation, with a greater proportion of coral cover bleached on reefs that were exposed to the highest accumulated heat stress this summer.

Reef snapshot: summer 2021-22 youtu.be

While corals can recover from bleaching episodes under the right environmental circumstances, those have not been reliably present, and the overall health of the Great Barrier Reef has rapidly deteriorated since the end of the 20th century. Between 1995 and 2020, the uniquely biodiverse natural wonder lost half of its coral populations. A study released in early 2021 noted that 98 percent of the Reef has been affected by bleaching since 1998.

Reefs are home to countless species of plants and animals found nowhere else on Earth, and they are threatened with extinction as the planet's reefs face the possibility of collapse.

Human activity – specifically the relentless burning of fossil fuels – is the unequivocal culprit behind the Reef's hastening ruination.

"This is the fourth mass bleaching event since 2016 and the sixth to occur on the Great Barrier Reef since 1998," the study explains. "Climate change is the greatest threat to the Great Barrier Reef. Only the strongest and fastest possible actions to decrease global greenhouse gas emissions will reduce the risks and limit the impacts of climate change on the Reef. Further impacts can be minimized by limiting global temperature increase to the maximum extent possible and fast-tracking actions to build Reef resilience."