Extensive Coral Bleaching Threatens Great Barrier Reef, Raising Fears of Seventh Mass Bleaching Event
The southern Great Barrier Reef is facing a dire situation as extensive coral bleaching due to heat stress has been discovered, raising concerns that a seventh mass bleaching event could be unfolding. Aerial surveys conducted by the Great Barrier Reef Marine Park Authority and Australian Institute of Marine Science revealed that bleaching was widespread and uniform across all surveyed reefs.
The teams conducted surveys over 27 inshore reefs in the Keppel Islands and Gladstone region, as well as 21 offshore reefs in the Capricorn Bunkers off the coast of southern Queensland. Dr. Mark Read, the authority’s director for reef health, noted that most coral displayed some level of bleaching, with white and fluorescent colonies observed in shallow reef areas.
The Great Barrier Reef, spanning nearly 133,000 square miles, is the world’s largest coral reef and home to a vast array of marine life. It contributes billions of dollars to the Australian economy annually and is renowned as one of the country’s greatest natural wonders. However, rising ocean temperatures, fueled by the continued use of planet-heating fossil fuels, are causing destructive bleaching events. The current El Niño, one of the strongest on record, is further exacerbating the situation by increasing ocean temperatures.
Coral bleaching occurs when stressed coral expels algae from its tissue, depriving it of a vital food source. Prolonged exposure to higher-than-normal water temperatures can lead to coral starvation and death, resulting in the characteristic white appearance as the coral’s carbonate skeleton is exposed.
While the southern part of the Great Barrier Reef is currently experiencing the most severe bleaching, reports of bleaching have been received from all other regions of the marine park. The reef authority plans to conduct extensive aerial and in-water surveys across the entire reef in the coming weeks to assess the severity and extent of the bleaching. Dr. Neal Cantin, senior research scientist with the Australian Institute of Marine Science, emphasized the need for underwater investigations to gain a deeper understanding of the bleaching’s severity and depth.
A CNN team that recently visited the Great Barrier Reef observed bleaching at Lady Elliot Island, the southern-most coral cay, as well as on four different outer reefs off Cairns in the middle section of the reef. Additionally, a separate report from James Cook University highlighted areas of moderate to severe coral bleaching around the Keppel Islands, where water temperatures were significantly higher than the summer average. Dr. Maya Srinivasan, a scientist at the university’s center for tropical water and aquatic ecosystem research, expressed her concern, stating that she had never felt the water as warm as it currently is and that some corals were already dying.
Scientists believe that corals can recover if ocean temperatures stabilize. Dr. Srinivasan explained that while fish abundance declines with coral cover during bleaching events, there is potential for recovery if enough time elapses between impacts. The Great Barrier Reef has previously experienced severe mass bleaching events in 2016, 2017, and 2020, with previous occurrences in 1998 and 2002. A bleaching event in 2022 during a La Niña event, which typically has a cooling influence, raised serious concerns about the reef’s future. Now, there are fears that 2024 could witness a seventh mass bleaching event.
David Ritter, CEO of Greenpeace Australia Pacific, expressed his concerns about the unfolding situation on the Great Barrier Reef. He stated that while official confirmation is awaited from the Marine Park Authority, reports of severe bleaching along the reef’s length indicate the likelihood of a seventh mass bleaching event. Ritter emphasized the need for urgent action to address climate change as an existential threat to the reef, criticizing the Australian government for expanding and subsidizing the coal and gas industry while claiming to prioritize the reef’s health.
The Great Barrier Reef’s plight is not an isolated incident. Last year, a record marine heatwave caused significant coral population declines in Florida and the wider Caribbean. Observers in Australia fear a similar fate awaits the country’s reefs. The warmest year on record in 2023 saw ocean temperatures reach unprecedented levels, resulting in the bleaching of entire reefs. The US National Oceanic and Atmospheric Administration (NOAA) recently added three new levels to its alert system to account for increasingly severe coral bleaching and higher mortality rates. The highest level, Alert Level 5, indicates that over 80% of corals in the highlighted area are at risk of dying due to prolonged high water temperatures.
Despite scientific evidence suggesting the risk of another mass bleaching event, the Great Barrier Reef was not added to the UNESCO World Heritage Committee’s list of sites “in danger” last year. Greenpeace’s Ritter criticized this decision and called for stronger action to protect the reef, including aligning emissions reduction plans with a 1.