CNN
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Record ocean warming has wreaked havoc on one of the world’s greatest natural wonders, with coral bleaching on Australia’s Great Barrier Reef reaching “catastrophic” levels, a new study has found.
More than 50 percent of affected corals monitored near an island south of the reef were killed last year during the most “severe and widespread bleaching” to hit the area, according to a team of Australian scientists.
In 2024, the Reef experienced its worst heat on record. Rising ocean temperatures have broken records, causing the reef’s seventh mass bleaching event. Corals turn white when ocean heat waves stress corals, causing them to excrete algae from their tissues, discoloring them.
The culprit is the burning of planet-warming fossil fuels, increasing global temperatures. Coral damage was also accelerated last year by the El Nino weather pattern, which warms ocean temperatures in this part of the world.
Scientists from the University of Sydney tracked 462 coral colonies at the reef’s One Tree Island over five months last year, beginning at the height of a heat wave in early February.
By May, 370 of those colonies had been bleached and by July, 52 percent of the bleached corals had died, according to a peer-reviewed journal published in Limnology and Oceanography Letters.
With some coral species monitoring mortality rates as high as 95%, researchers observed the onset of “colony collapse” where the dead skeleton detaches from the reef and turns into debris.
Another species, Goniopora, was affected by black band disease, which attacks and can kill coral tissue.
“Our findings underscore the need for urgent action to protect coral reefs, which are not only biodiversity hotspots but also important for food security and coastal protection,” said lead author Maria Byrne, from the university’s School of Life and Environmental Sciences. are also important for conservation.”
Byrne said the area studied is in a protected part of the reef, far from the coast and free from mining activities and tourism.
But the rock, “despite its protected status, was not immune to the extreme heat stress that triggered this catastrophic bleaching event,” he said.
Covering approximately 133,000 square miles (345,000 square kilometers), the Great Barrier Reef is the world’s largest coral reef, home to over 1,500 species of fish. More than 411 species of hard corals are found. It contributes billions of dollars to Australia’s economy each year, mainly through tourism, and is a major draw for overseas visitors to the country and Promoted as one of the greatest natural wonders of the world.
The authors said that mass bleaching is becoming “a biennial event” and thus “reinforces the need for urgent global action to adhere to ambitious climate and low-emissions targets.”
The study found that bleaching areas of the reef were not previously affected, and disease and death of coral species were observed, the study reported.
“Looking at the impact on a reef that has so far avoided large-scale bleaching,” said Shauna Fu, a marine scientist and co-author of the study. “The high rates of death and disease, especially in such a remote and pristine area, highlight the gravity of the situation.”
In February last year, CNN observed bleaching on five different reefs spread across the northern and southern parts of the ecologically important but fragile site.
Severe mass bleaching on the Great Barrier Reef was previously observed in 1998, 2002, 2016, 2017, 2020 and 2022.
The 2022 bleaching was the first during a La Niña event, El Nino’s counterpart, which has a cooling effect – raising serious concerns about the reef landscape.
The authors said their research was a “wake-up call for policymakers and conservationists” because its implications extend beyond ecology and conservation to communities that depend on the reef for fishing, tourism and coastal protection. .
“The resilience of coral reefs is being tested like never before, and we must prioritize strategies that adapt to climate change,” said study co-author Ana Vela Consejo of the university’s School of Geosciences. to enhance their ability to compete.”
“Our findings emphasize the need for immediate and effective management interventions to protect these ecosystems.”
