It’s one of the natural wonders of the world, but experts say the Great Barrier Reef is being slowly killed off .
The reef is suffering from an effect called coral bleaching. It occurs when warming water patterns (caused by climate change) force the coral to expel algae. Algae provides coral with 90% of it energy and, without it, the colourful reef turns white .
Last year, coral bleaching hit 90% of the reef and killed nearly 20% of it.
This year, the trend has continued.
Marine biologist and conservation photographer for Greenpeace Brett Monroe Garner filmed the coral on Feb. 20 and in a statement via Greenpeace said, "I’ve been photographing this area of the reef for several years now and what we’re seeing is unprecedented."
Mildly bleached coral can recover if the temperature drops. And while the process can occur naturally, scientists are concerned rising sea temperatures caused by global warming is magnifying the damage.
“In these photos nearly 100% of the corals are bleaching and who knows how many will recover? Algae is already beginning to overgrow many of the corals," said Garner.
“Just a few months ago, these corals were full of colour and life. Now, everywhere you look is white.
"The corals aren’t getting the chance to bounce back from last year’s bleaching event. If this is the new normal, we’re in trouble.”
Bleaching has a knock-on effect of leaving sensitive underwater ecosystems unable to recover.
UNESCO’s World Heritage Committee stopped short of placing the Great Barrier Reef on an "in danger" list last May but asked the Australian government for an update on its progress in safeguarding the reef.
At 348,000 sq km (134,400 sq miles), the Great Barrier Reef is the biggest coral reef in the world.
Future surveys will continue to monitor the bleaching rate across the reef, but the death toll of the coral won’t be known for months yet.