- Great Barrier Reef: Highest water temperature in 400 years
Sea surface temperatures around the Great Barrier Reef in Australia have reached a new peak: According to an Australian research team, it has never been as warm there 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, sea temperatures were relatively stable. The study shows that there was a steady increase from 1960 to 2024, with an average warming of 0.12 degrees per decade between January and March.
However, there are also uncertainties in the reconstructed temperature data from before 1900. Some of the chemical components in the corals used for temperature modeling may have been influenced by other variables such as salinity. These uncertainties could be reduced with additional samples of coral cores from the region.
Five mass bleaching events in eight years
With the rise in sea temperatures due to global warming, the risk of mass bleaching and coral deaths in Australia's natural wonder also increases. The first mass coral bleaching was 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 events (2016, 2017, 2020, 2022, and 2024) on average from January to March than in any year reconstructed 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 warn that probably 70 to 90 percent of corals worldwide will be lost - even if global warming is kept below the 1.5-degree Celsius target of the Paris Agreement. Furthermore, future coral reefs will likely have a different community structure with a lower diversity of coral species.
The following findings by Benjamin Henley and his team from the University of Melbourne in Australia are based on their analysis of coral skeletons and sea surface temperature data.The 'five mass bleaching events' occurring at the Great Barrier Reef in recent years can be directly linked to the warming trend observed in the reconstructed sea surface temperatures.
