In Australia, bleaching reached 98% of the major barrier

Coral reefs, this important marine ecosystem, are under irreversible extreme pressure of climate change. A study released on Thursday, November 4, reveals that since 1998, 98% of the Great Barrier Reef in Australian rocks has been whitewashed and the deformed portion of the world’s largest coral reefs. According to the published article In review Current Biology, Only 2% of this massive underwater ecosystem has survived the event since the major bleaching episode since 1998.

Leading author Terry Hughes says the frequency, intensity and magnitude of the ocean heat waves that cause this bleaching are increasing, says James-Cook, director of the University’s Special Center for Coral Studies in Queensland.

“Five major bleaching episodes since 1998 have turned the Great Barrier Reef into a checkerboard of rocks with very different recent histories. The 2% reefs have bleached at least once since 2016, up to 80% completely escaping bleaching.”

Bleaching is a futile event that results in discoloration. This causes the water temperature to rise, which causes the coral to expel the algae that give the coral its color and its nutrients. The Great Barrier, a UNESCO World Heritage Site in 1981, bleached three unprecedented chapters during the heat waves of 2016, 2017 and 2020.

This phenomenon, which is added to the acidification of the oceans, has great effects on ecosystems. Corals, a type of oasis in marine deserts, represent only 0.2% of the ocean surface, but 30% of known marine biodiversity, which provides food resources. They provide many ecosystem services to humans, protect coastal areas from erosion, feed many people (fishing, aquaculture) and create tourism.

“Acting is important”

While acknowledging that the 2,300-kilometer stretch is a long-term opportunity for the environment, researchers confirmed in July that the corals have shown signs of healing since the last bleaching. “Too bad”.

Research published on Thursday shows that corals that are already exposed to heat waves are subject to thermal stress, but Sean Connolly, co-editor of the Smithsonian Tropical Research Institute, says that frequent bleaching and, most importantly, reduce the elasticity of corals. “The coral needs more time before another cycle of thermal stress to create children that will scatter, settle and recover the deformed parts of the coral.”, He explains. “It is important to take action to control climate change.”

The reefs are threatened by hurricanes, and the increasing coral-eating starfish due to frequent climate change and purple agglomeration, pollution and agricultural flow.

The study comes ahead of the United Nations Climate Summit in Glasgow, Scotland, where Australia, a major exporter of fossil energy, has promised to achieve carbon neutrality by 2050.