The Great Barrier Reef is at risk

Records from centuries ago: Water temperatures at Australia’s famous Great Barrier Reef have been warmer in the past decade than in 400 years, according to a scientific study published Wednesday.

According to the study published in the prestigious scientific journal, the values ​​have increased every year since 1960, but were particularly high during the recent coral bleaching events. natureThe warming waters are likely the result of climate change caused by human activity. Study co-author Helen McGregor said she was “extremely concerned” about the “unprecedented” rise in water temperatures.

Warming up by 0.12 degrees per year

Stretching 2,300 km along the coast of Queensland (northeastern Australia), the Great Barrier Reef is considered the world’s largest living structure. It has an extremely rich biodiversity with more than 600 species of coral and 1,625 species of fish. Coral dieback causes discoloration due to rising water temperatures, which causes the symbiotic algae to be expelled, giving them their bright colors. If the high temperatures persist, the corals turn white and die.

Australian researchers studied the surface temperatures of the Coral Sea using ancient coral samples, reconstructing temperatures since 1618. While temperatures were relatively stable before 1900, they found that the sea has warmed by an average of 0.12 degrees Celsius per year since 1960.

Too fast for corals

Temperatures have been even higher during recent mass bleaching events (2016, 2017, 2020, 2022 and 2024). Even if corals are able to recover, Helen McGregor warns, rising water temperatures combined with successive bleaching events will test them.

“From what we have seen so far, it looks like these changes are happening too fast for corals to adapt, and this really threatens coral reefs as we know them,” warned climate researchers at Australia’s University of Wollongong.

This year there has been a devastating bleaching event

This year’s bleaching event was one of the worst and most widespread ever observed, leaving 81% of the reef severely damaged, according to the latest government data. Scientists will only know for months how much of the reef cannot be saved. “At the moment we can see the reef is resisting,” Richard Lake, head of oceans at WWF Australia, told AFP. “It has recovered from previous coral bleaching events but at some point the elastic band breaks.”

“Coral reefs are the first ecosystem on Earth to be threatened by climate change,” he warned. “We have to hope that the world does not sit idly by and let this happen. But there is less than a second left until midnight,” Richard Lake warned.

UNESCO puts pressure on Australia

In June, UNESCO asked Australia to take “urgent” steps to protect the Great Barrier Reef, particularly by setting more ambitious climate targets. The UN agency wants Canberra to submit an update on coral protection and conservation efforts by early 2025, but did not recommend the site be added to the List of World Heritage in Danger.

Australia has invested around $3.2 billion (€1.92 billion) to improve water quality, reduce the impact of climate change and protect endangered species, but the country, one of the world’s largest exporters of gas and coal, only recently set a goal of carbon neutrality.