Is Climate Change Killing The Great Barrier Reef? Bleaching Turns Colorful Coral 'Bone White'

Divers swimming along the Great Barrier Reef off Australia's northeastern tip witnessed a sobering sight this week.

This area, off the coast of Lizard Island near Cooktown, is considered the most pristine section of the reef. Now, "vast stretches" of the once-colorful organisms have turned "bone white," Smithsonian reported. The damage is near total, and similar bleaching has struck areas nearby.

"I have never seen coral this heavily bleached," said Professor Justin Marshall, the head of CoralWatch. "And we are seeing algae growing on parts, which means it has died."

Half of the coral in that region has died due to coral bleaching, which is another consequence of climate change. However, it has been made worse by El Nino. Coral bleaching results when ocean temperature gets too warm, and unfortunately, the ocean has been too warm for too long.

According to National Geographic, the coral die-off in the Great Barrier Reef has tentatively been linked to rising ocean temperatures. This is the worst bleaching event to hit this area of the reef, which is the world's largest, ever observed.

Ocean temperatures in northern Australia have been 1.8 degrees above normal since January, which is enough to cause coral bleaching. Russell Reichelt, Chairman of the Great Barrier Reef Marine Park Authority, said the corals in the area "experienced extremely hot and still conditions this summer, and were effectively bathed in warm water for months, creating heat stress that they could no longer cope with."

As the Inquisitr previously reported, coral bleaching results when the oceans become very warm due to climate change and/or El Niño. The process starts when the waters are only one degree higher than normal for about a couple months and occurs because the organisms didn't evolve to live in warm waters for long periods of time.

These conditions stress coral reefs, and as a result, they expel the algae that give them both their color and nutrients. With the loss of this algae, reefs lose a source of food and become very vulnerable to disease. They can handle it in the short term, but not in the long term. These delicate ecosystems keep getting hit before they can recover, leading to a massive die-off.

Luckily, most of the Great Barrier Reef has been spared from coral bleaching, so far, thanks to heavy rain and cloud cover counteracting the warm temperatures.

This isn't the only threat to the world's reefs: nutrient runoff from farms, lawns, and industrial chemicals is damaging them, as are ocean acidification and overfishing. Since the Industrial Revolution, the water has become 30 percent more acidic due to climate change. Carbon dioxide fills the air and traps heat while coal, oil, and other fossil fuels turn into excess carbonic acid, which is then absorbed by the oceans.

This is making it harder for coral reefs to grow and recover from bleaching.

The Australian government has responded by raising their threat response level. This will deploy surveying teams to scour the entire system for damage; it covers 133,000 square miles and stretches 1,200 miles along the coast, CNN reported.

"The health and future of the Great Barrier Reef is a priority for us," said Reichelt. "Bleaching reinforces the need for us to continue working with our partners to improve the reef's resilience to give it the best possible chance of dealing with climate change impacts."

Coral bleaching is part of a global trend. In the past year, 12 percent of the world's reefs have been bleached due to a combination of El Niño and climate change. Nearly half of these won't recover and will disappear. The warming is expected to continue through 2016, creating one of the longest global coral bleaching events in history.

[Image via ProDesign studio/Shutterstock]