By ROD McGUIRK
MELBOURNE, Australia (AP) — According to Australian authorities, the Great Barrier Reef has had its largest yearly loss of live coral throughout the majority of its breadth in forty years of record-keeping.
However, the Australian Institute of Marine Science said in its annual survey on Wednesday that the area of living coral across the iconic reef system is now close to its long-term average due to rising coral cover since 2017 and coral deaths brought on primarily by bleaching last year linked to climate change.
According to the assessment, the alteration highlights a new degree of instability on the UNESCO World Heritage Site.
According to Mike Emslie, who oversees the long-term monitoring program for the tropical marine research organization, the amount of living coral cover measured in 2024 was the highest in 39 years of surveys.
He claimed that the world’s largest reef ecosystem, which spans 133,000 square miles off the northeast Australian coast, had been somewhat protected from the severe warming effects by the losses resulting from such a high base of coral cover.
According to Emslie on Thursday, these are significant repercussions and proof that the Great Barrier Reef is beginning to suffer from the growing frequency of coral bleaching.
“These are record declines that we have seen in any one year of monitoring,” he continued, “even though there is still a lot of coral cover out there.”
The Great Barrier Reef, which stretches 900 miles along the Queensland state coast, is divided into three equal-sized sections by Emslie’s agency: the northern, central, and southern sectors.
According to the report, the amount of living coral cover decreased by 14% in the center region, a quarter in the north, and nearly a third in the south in a single year.
According to the U.S. National Oceanic and Atmospheric Administration’s coral reef watch, heat stress has damaged nearly 84% of the world’s coral reef area, including the Great Barrier Reef, and the world is currently experiencing its largest and fourth mass coral bleaching event on record as a result of record global heat in 2023 and 2024. At least 83 nations have been affected thus far.
Beginning in January 2023, this bleaching event was deemed a global crisis in April 2024. It considerably surpassed the last largest global coral bleaching event, which occurred between 2014 and 2017 and resulted in 68.2% of corals bleaching due to heat stress.
This most recent occurrence saw large regions of Australia, but not the Great Barrier Reef, reach the maximum or almost maximum bleaching alert rating. Widespread coral bleaching was discovered by Australia in March of this year when it began aircraft scans of 281 reefs along the northern Great Barrier Reef and the Torres Strait. 78 of the 281 reefs had bleaching levels more than 30%.
Long-term exposure to hot water makes it difficult for coral to grow and occasionally even survive. They may withstand brief outbursts, but after a few weeks and high temperatures, the coral bleaches—that is, turns white—because the algae that give it its color and life in the tissue are expelled. Although they are weaker and more susceptible to illness, bleached corals are still alive.
After these widespread worldwide bleaching events, coral reefs frequently recover, but they are frequently not as robust as they were previously.
The United Nations Intergovernmental Panel on Climate Change said in 2018 that coral reefs are a peculiar and endangered system because of climate change, and that they are particularly susceptible to global warming that exceeds 1.5 degrees Celsius (2.7 degrees Fahrenheit) since pre-industrial times. Since pre-industrial times, the global temperature has increased by 1.3 degrees Celsius. According to that analysis, tropical corals might be considerably more susceptible to climate change than studies from 2014 suggested.
According to the report, the Great Barrier Reef’s two consecutive major bleaching events in the middle of the 2010s raise the possibility that the scientific community miscalculated the risks that climate change poses to coral reefs.
At 1.2 C, warm water (tropical) coral reefs are expected to be at very high risk of impact; the majority of the evidence points to the extinction of coral-dominated ecosystems at this temperature or above. According to the analysis, coral abundance will be almost nonexistent in numerous places at this time.
This article was written by Seth Borenstein, a science writer for the Associated Press in Washington, D.C.
