Coral bleaching is killing the world’s most impressive reef. These stunning photos and facts reveal exactly what’s at stake.

Last week, a pretty distressing figure made waves — though probably not as many as it should have: 93 percent of the Great Barrier Reef (the world’s largest coral reef) is now in danger of dying. Here’s what’s at stake if one of the world’s most unique ecosystems collapses:

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The Great Barrier Reef Could Be Global Warming’s Latest Victim
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What's Behind The Coral Sickness?

The explanation behind the dire stats about the Great Barrier Reef is a process called coral bleaching. This occurs when the coral becomes stressed -- either by prolonged warm temperatures or greater concentrations of carbon dioxide in the water, which causes ocean acidification.

In these conditions, the coral releases the symbiotic algae that live in its tissues as a defense mechanism. When these algae (called Zooxanthellae) leave, the coral loses access to its main source of food and the ability to effectively remove waste, and thus becomes prone to disease.

The algae also provides the coral with its brilliant color, so when they’re gone, all that’s left is a white exoskeleton, hence being called "bleached."

While bleached coral aren’t dead, they are in danger of death if oceanic conditions don’t become favorable again. Their death impacts more than just the environment: According to the Great Barrier Reef Marine Park Authority, the reef generates $4.45 billion in annual tourism revenue and supports nearly 70,000 jobs in Australia.

“We’ve never seen anything like this scale of bleaching before. In the northern Great Barrier Reef, it’s like 10 cyclones have come ashore all at once,” Professor Terry Hughes, convenor of the National Coral Bleaching Taskforce that is documenting and studying the event, said in a statement.

What Are Scientists Doing About It?

While the Great Barrier Reef -- and other reefs like it -- is undeniably suffering as the effects of climate change become more prolonged and pronounced, some reefs have fared better than others in the process.

That these reefs and coral species have not been hit as hard as others has scientists scrambling to learn why, which Grist explains "could be crucial to ensure reefs continue to survive as oceans temperatures continue their inexorable rise and water becomes more acidic due to climate change."

Others are still hopeful that this trend can be reversed if governments choose to act.

“Thankfully, many parts of the reef are still in excellent shape, but we can’t just ignore coral bleaching and hope for a swift recovery. Short-term development policies have to be weighed up against long-term environmental damage, including impacts on the reef from climate change,” Daniel Gschwind, Chief Executive of the Queensland Tourism Industry Council, said.

Next, check out these animal signs that the Earth is sick and this explainer on global warming.

Erin Kelly
Erin Kelly
Erin Kelly is a freelance writer, artist and video editor that splits her time between the humid Midwest and the dusty corners of her mind.
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