Illustration for article titled The Great Barrier Reef Faces Third Mass Bleaching Event in Five Years

Australia’s forests burned over the summer, but now its underwater ecosystems are in trouble, too. The Great Barrier Reef is facing some severe stress due to extreme heat and faces a “widespread bleaching event,” according to an update from the National Oceanic and Atmospheric Administration’s Coral Reef Watch.

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When a coral bleaches, it expels the symbiotic algae that help it produce food and turns white. This can push a coral to death, and the world has seen enough loss of corals over the past few years. The Great Barrier Reef has been hit particularly hard, though, and this year’s bleaching will deal yet another blow to one of the wonders of the natural world.

Sea surface temperatures began to rise in January. The waters have been 1 degree Celsius (1.8 degrees Fahrenheit) higher than the maximum monthly mean. High pressure is forecast to lock in sunny skies, which will further heat up the waters and worsen the impacts on coral.

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The forecast from Coral Reef Watch shows that the entire swath of the Great Barrier Reef—which covers an area roughly the size of Germany—is projected to see level 2 bleaching, its highest level, for the rest of the month. The agency describes that as “severe, widespread bleaching and significant mortality.” The huge scale of the bleaching comes with an extremely slight sliver of good news: This year’s bleaching isn’t likely to be as intense as recent years.

Similar bleaching events in 2016 and 2017 left the Great Barrier Reef seriously degraded. Fast-growing coral species that help the reef maintain its structure haven’t been able to bounce back. Since then, the remaining corals have been having a rough time reproducing enough baby corals to keep the ecosystem thriving.

As with land heat waves, it’s becoming impossible to disentangle the influence of climate change. The Coral Sea where the Great Barrier Reef is found has warmed steadily over time, increasing the odds of extreme heating. Globally, research published last year showed what researchers call “surprise” marine heat events are increasing in every ocean basin.

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These heat waves take a particularly hard toll on coral. Another mass bleaching event is the last thing this reef needs. This one, which is just getting started, appears to be less severe than what the reef experienced in 2016 and 2017. Bleaching should worsen beginning next week. Still, that doesn’t mean it won’t come without consequences.

The Great Barrier Reef is a major driver of the local economy. It’s worth an estimated $56 billion to the Australian economy as a source of tourism dollars and its status as a global icon, and 64,000 jobs are tied to its fate. However, it’s not just the tourism industry that benefits from the reef. Corals act as a buffer that protects coasts from cyclones and storms and provide homes to wildlife.

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Losing the Great Barrier Reef would not only be a direct hit to the Australian economy. It would threaten the world’s biodiversity at large during a time when we’re already losing enough species to the climate crisis.

We’ve lost half of all this region’s corals since bleaching grew severe in 2016. This latest event is likely to continue a dangerous pattern of death and loss.

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Senior staff writer, Earther. All things environmental justice, please. I'm addicted to Stardew and love few things more than I love my cat.

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