High water temperatures threaten the Great Barrier Reef
The Great Barrier Reef is the largest coral reef in the world and a natural wonder. However, the steadily rising water temperatures could soon destroy the reef. Scientists are therefore calling for swift action to combat climate change.
The water temperatures around the Great Barrier Reef in Australia have reached a new record high: According to an Australian research team, it has never been as warm there in the past 400 years as it is this year. The warming can be attributed to human influences, the team writes in the journal "Nature".
The researchers led by Benjamin Henley from the University of Melbourne in Australia have reconstructed the sea surface temperatures from 1618 to 1995 using coral skeletons from the reef and compared them with the recorded sea surface temperature data from 1900 to 2024.
Before the year 1900, the water temperatures were relatively stable. The study shows that there was a steady increase from 1960 to 2024: An average warming of 0.12 degrees per decade was measured in the period from January to March.
Nevertheless, there are also uncertainties in the reconstructed temperature data from before 1900. Some of the chemical components in the corals used for modeling temperatures may have been influenced by other variables such as salinity. Additional sampling of coral cores from the region could reduce these uncertainties.
Five mass bleaching events in eight years
With the increase in water temperatures due to global warming, the risk of mass bleaching and coral death in Australia's natural wonder is also increasing. Mass coral bleaching was first observed in 1980; in recent years, they have become more frequent.
In March of this year, the fifth mass bleaching event within eight years was confirmed at the Great Barrier Reef, which hosts a diverse ecological network. The researchers show that it was significantly warmer in the years of the last mass bleaching (2016, 2017, 2020, 2022, and 2024) on average from January to March than in any year of the reconstruction before 1900.
"Without swift, coordinated, and ambitious global action to combat climate change, we will likely witness the demise of one of the great natural wonders of the Earth," the team writes.
The scientists point out that probably 70 to 90 percent of the world's corals will be lost - even if global warming is kept below the target of the Paris Agreement of 1.5 degrees Celsius. Furthermore, future coral reefs would likely have a different community structure with a lower diversity of coral species.
The record-breaking high water temperatures at the Great Barrier Reef are not only causing concern but also posing a significant threat. According to the research led by Benjamin Henley's team, the reef has experienced five mass bleaching events in the past eight years, with the latest occurrence confirmed in March 2024.
