At least 97% of corals in the northern Great Barrier Reef have died

“It’s not pretty, but I’m not going to apologize for the data. Bear with the inconvenience. When is enough enough?” said one of the scientists behind the discovery.

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Almost all of the corals on a reef near Lizard Island in Australia have died following one of the worst mass bleaching events ever experienced by the world’s largest coral reef system, new drone footage shows.

Scientists from Macquarie University, James Cook University and GeoNadir first mapped the area around Lizard Island in March 2024 and repeated the survey this month. The images they collected showed that at least 97% of the reef had died amid record-breaking sea surface temperatures.

“This isn’t pretty, but I won’t apologize for the data. Bear with the inconvenience. When is enough enough?” wrote Dr. Karen Joyce, one of the scientists behind the discovery, on X.

In April, the U.S. National Oceanic and Atmospheric Administration (NOAA) and the International Coral Reef Initiative (ICRI) – a partnership of 101 nations and countries dedicated to destroying reefs around the world – confirmed that coral bleaching is occurring for the fourth time worldwide, the second in the last decade.

The event is directly linked to rising sea surface temperatures, which broke another monthly record in June for the fourteenth consecutive month. Seas warmed last year in response to the return of El Niño, a weather phenomenon associated with the unusual warming of surface waters in the eastern equatorial Pacific. But that trend has continued well into 2024, despite signs that El Niño is gradually weakening.

Coral bleaching is a phenomenon in which coral reefs expel the microscopic marine algae called zooxanthellae that live in their tissues when they are under stress – be it heat, ocean acidification or human activities. As a result, the coral tissue becomes transparent and loses its characteristic bright colors, exposing the white exoskeleton underneath.

More on the topic: Explanatory video: What is coral bleaching?

While bleaching does not mean that the corals are dead, it does increase their vulnerability to marine diseases and starvation, which can eventually lead to death. The longer corals bleach under various stresses, the harder it becomes for the algae to return, making revival of the reefs impossible.

Disappearing ecosystems

Coral reefs are critically important ecosystems found in more than 100 countries and territories and home to at least 25% of all marine species. They are essential for maintaining the Earth’s vast and interconnected web of marine biodiversity and provide ecosystem services valued at up to US$9.9 trillion per year. They are sometimes called the “rainforests of the sea” because they act as carbon sinks by absorbing the excess carbon dioxide in the water.

Unfortunately, reefs are disappearing at an alarming rate. According to the latest report from the Global Coral Reef Monitoring Network (GCRMN), about 14% of corals have been lost worldwide since 2009.

While coral bleaching may be a natural process that occurs due to rising ocean temperatures in the summer months or during natural weather phenomena such as El Niño, an increase in marine heatwaves due to human activities has led to more frequent and larger bleaching events worldwide.

One of the best examples of coral bleaching is the Great Barrier Reef, the world’s largest and longest reef system off the coast of Queensland, Australia. It covers about 350,000 square kilometers – an area larger than the UK and Ireland combined. The stunning coral reef system has already been the victim of mass bleaching six times in 1998, 2002, 2016, 2017, 2020 and 2024. The events in 2016 and 2017 were so severe that they resulted in the death of 50% of the iconic reef.

In addition to Australia, coral dieback is particularly pronounced in regions such as South Asia, the Pacific, East Asia, the western Indian Ocean, the Gulf and the Gulf of Oman.

Earlier this week, UNESCO called on Australia to set more ambitious targets to protect the Great Barrier Reef and expressed its “extreme concern” about recent coral bleaching.