91% of the Great Barrier Reef is bleached due to heat wave

Warming waters caused by climate change have bleached corals on 91% of the Great Barrier Reef’s reefs this year, according to an Australian government agency.

Scientists from the Great Barrier Reef Park Authority (GBRMPA) confirmed in March that this is the sixth recorded mass bleaching of reefs and the fourth since 2016.

But the report released Tuesday, “Reef Photography: Summer 2021-22,” showed that nearly all of the coral reefs investigated along the 2,300-kilometer system were impacted by bleaching.

Coral reefs are some of the most vibrant ecosystems on Earth – between a quarter and a third of all marine species depend on them at some point in their life cycle. But the planet’s rapid warming due to human emissions of greenhouse gases is causing above-average temperatures in the waters, leading to damage such as mass bleaching.

Coral bleaching tends to happen when the water temperature gets much higher than normal. But for the first time, this bleaching does come with La Niña, a weather event that is characterized by lower-than-normal temperatures in the equatorial Pacific Ocean, the Authority’s scientists said.

The report investigated around 719 reefs, observing them from a plane flying at low altitude during the 2021-2022 Australian summer season, and identified that 654 reefs, 91%, “exhibited some bleaching”.

“Surveys confirm a massive bleaching incident, with coral bleaching observed on multiple reefs in all regions. This is the fourth incident since 2016, and the sixth to occur on the Barrier since 1998,” the Great Barrier Reef Park Authority said of its findings.

The waters of the Great Barrier Reef began to warm in December 2021, and exceeded “historic summer highs”. They were hit by three heat waves during the summer until early April 2022, which increased “thermal stress” in the central and northern areas of the reef, according to the report.

Corals under stress eject algae from their tissues, which deprives them of a food source. If conditions do not improve, corals can starve and die, turning white as their carbon skeleton is exposed.

“Even the most robust corals require nearly a decade to recover,” Jodie Rummer, an associate professor of marine biology at James Cook University in Townsville, told CNN in March.

“So we’re missing that recovery window. We are seeing one bleaching incident after another, one heat wave after another. And corals are just not adapting to the new conditions,” she said.

The report warned that the climate crisis remains the biggest threat to the Barrier, and that “reef-disturbing events are becoming more frequent”.

It is the fourth mass bleaching event in six years and the first since 2020, when about a quarter of the reefs inspected showed signs of severe bleaching. This event occurred just three years after followed incidents of bleaching in 2016 and 2017. Previous bleachings took place in 1998 and 2002.

Scientists say time for reefs to recover is running out and governments urgently need to address the root cause of the problem: the climate crisis.

“To give our reef a fighting chance, we need to tackle problem number one: climate change. No funding is going to stop these bleaching unless we lower our emissions this decade,” Amanda McKenzie, CEO of the Climate Council said in March.

The Great Barrier Reef is one of Australia’s national treasures, stretching 2,300 kilometers off the coast of Queensland, and attracting around three million tourists a year before the pandemic.

The Australian government has faced pressure from UNESCO to prove it is doing enough to save the reef, and has been warned by global climate experts, among others, for not doing enough to make the transition from fossil fuels to more sustainable and sustainable ones. reduce greenhouse gas emissions.

The report’s publication comes after leading scientists drew the agency’s attention to releasing their findings ahead of federal elections on May 21.