As It Happens

Great Barrier Reef's latest 'mass bleaching' linked entirely to climate change: scientist

Mark Eakin of Coral Reef Watch tells As It Happens that coral bleaching on the Great Barrier Reef is more widespread but hopefully less severe than in recent years.

Previous bleachings partly blamed on El Niño and La Niña weather events, says scientist

In this undated file photo, a diver swims on Australia's Great Barrier Reef. (Brain Cassey/Associated Press, File)


Coral on the Great Barrier Reef is undergoing the third "mass bleaching" in five years, and this one is particularly worrying, says Mark Eakin, a co-ordinator with Coral Reef Watch.

"What we're really seeing is a bleaching event that's being driven by climate change instead of a particular event," Eakin told As It Happens host Carol Off.

The last two mass bleachings occurred in 2016 and 2017. Both could be partially attributed to El Niño and La Niña, global weather patterns that affect ocean surface temperatures. 

At this point in 2020, neither event is occurring.

"Despite that, we're looking at January of this year being the warmest January ever and February being the second warmest ever," Eakin said.

"That's frightening because that means that we're moving into a new regime where just the warming that we're seeing on a global basis is causing severe bleaching."

Eakin, who has a Ph.D. in biological oceanography, works for Coral Reef Watch, a U.S. governmental organization that forecasts and monitors global sea surface temperatures.

Coral is normally colourful, but bleaches when it gets too warm by ejecting the algae that gives it its colour. This makes their white skeletons visible. Intense or long-term bleaching can kill coral.

"When you have that much death of corals like we had in 2016 and 2017, that sort of thing takes a decade or longer for the corals to even start to recover."

Mark Eakin works for Coral Reef Watch, a U.S. governmental organization that forecasts and monitors global sea surface temperatures. (Courtesy Mark Eakin)

The Great Barrier Reef stretches off the northeast coast of Australia, covers 348,000 square kilometres and contains 400 types of coral. 

About 29 per cent of corals on the reef died due to warming in 2016 and in 2017, about 22 per cent died, Eakin said. 

This year, bleaching is more widespread than it was in 2016 or 2017, but Eakin said he hopes it's less severe. 

COVID-19 response brings hope

Co-ordinated national and global responses to fight the COVID-19 pandemic give Eakin hope, he says. 

"People have responded to this COVID-19 by taking action, by changing their lives and by saying, 'We can do this. We can work together,'" he said.

"My hope is through this event, people are going to say: 'You know what? Climate change is just as big a problem. It's an existential threat to humans and to a lot of important ecosystems. We can do this. We can work together.'"

Written by Justin Chandler. Interview produced by Kate Cornick. 

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