Worse coral whitening never recorded for reefs from Western Australia

The world-renowned coral reefs along the coast of Australia-Western (WA) have suffered the worst bleaching never recorded after the longest, largest and intense marine heat wave, according to scientists.

Between last August and May, the warmer water temperatures led to significant thermal stress on reefs, which means that a lot of corals expel algae that give them life and color – a process called whitening, which is often deadly.

Damage – which will take months to assess – extends over 1,500 km (932 miles) and includes areas previously unscathed by climate change.

The coral reefs around the world suffer from a global two -year coral whitening event due to the record temperatures of the ocean.

Eight weeks of thermal stress are generally sufficient to kill coral, and the first estimates showed that many WA reefs suffered between 15 and 30, said Australia Marine Science Agency.

“The length and intensity of thermal stress, and its imprint in several regions, is something that we have never seen before on most of the reefs of Australia-Western,” said James Gilmour, of the Australian Institute of Marine Science (AIMS).

In a new report, AIMS researchers found that the 2024-25 season was the “whitening of the most severe corals ever recorded” for Wa coral reefs through northwest and central reefs.

“The areas that had given us hope because they would have rarely or not bleached before – like the Shoals Rowley, North Kimberley and Ningaloo – were touched this time. Finally, climate heating has caught up with these reefs,” he said.

Ningalo Reef is a site classified by World Heritage, as is the Grande Barrier Reef on the east coast of Australia which has suffered from the laundering of major corals in recent years.

Last week, a new report revealed that the major barrier reef – the largest coral system in the world extending over 2,300 km (1,429 miles) – experienced its greatest drop in coral in almost four decades.

Federal Minister of the Environment, Murray Watt, told Australian Broadcasting Corporation that coral damage to Ningalo “underline the need for Australia and the world to take urgent measures, in particular by achieving zero net programs”.

Climate change means that whitening events are becoming more and more frequent, more intense and more widespread, which, according to Dr. Gilmore, gives coral reefs – which need 10 to 15 years to recover – shortly to bounce back.

“Climate change caused by carbon emissions is the greatest threat to our coral reefs and all reefs around the world,” he said.

The UN previously warned that even if the world limits the global temperature is 1.5 ° C above pre-industrial levels, between 70 and 90% of the tropical coral reefs in the world will die.