Great Barrier Reef: aerial survey reveals extent of coral bleaching in Australia

An aerial survey is revealing the worst bleaching ever seen on northern parts of the Great Barrier Reef, as the scientist leading the survey live-tweets the devastation and pleads for the world to take action on climate change, The Guardian reports.

Last week Terry Hughes, a professor at James Cook University and convener of the National Coral Bleaching Taskforce, told the British publication that Australia he planned to hire a charter plane and map the bleaching to see how bad it was.

They would start from Cairns and fly north, he said. “We’ll expand that initial aerial survey to crisscross the whole northern region and map it all out.”

Now, using both planes and helicopters, Hughes has found what he says is the worst bleaching in the region he has ever seen.

On Tuesday, Hughes said he surveyed 600km of reef and found that more than 60% of it had been bleached.

That was just two days after the Great Barrier Reef Marine Park Authority raised the threat level of coral bleaching to the highest possible alert, “level 3” , indicating “severe regional bleaching” in the northernmost quarter of the 344,400 sq km marine park.

On Wednesday Hughes upgraded to a helicopter and continued the survey.

Over the following days, Hughes tweeted photographs of reef after reef, all appearing stark white.

On day three, he said only four of 400 reefs he saw were not bleached and that, while there had been bleaching in 1998 and 2002, this event was the worst.

Over the following days, Hughes tweeted photographs of reef after reef, all appearing stark white.

On day three, he said only four of 400 reefs he saw were not bleached and that, while there had been bleaching in 1998 and 2002, this event was the worst.

Bleaching occurs when coral gets stressed, usually by heat, and it expels the colourful algae that live inside it, giving it its brilliant color and providing it with most of the energy it needs. If it stays bleached for long enough, the corals die and the reefs risk being colonized by other organisms such as seaweed.

This bleaching event is linked to the current El Niño, which raises temperatures in the region, on top of climate change-induced warming.

While Hughes surveyed the reefs from the air, other teams were in ships, examining the coral up close to get a more in-depth picture of which corals were bleaching, he said.