Great Barrier Reef sees record coral bleaching

A new report has confirmed the largest die-off of coral along Australia's Great Barrier Reef.

It's an unprecedented coral die-off, but there's also some good news

Dead table corals killed by bleaching, northern Great Barrier Reef (ARC Centre of Excellence Coral Reef Studies)

A new report has confirmed the largest die-off of coral along Australia's Great Barrier Reef.

Earlier this year, Coral Watch, a citizen science project based out of the University of Queensland, released startling images of severe coral bleaching along the Great Barrier Reef, the largest living structure on Earth.

Coral is composed of thousands of small creatures called polyps that can only thrive in a very narrow range of temperatures. Microscopic algae live inside the tissue and provide coral with their colour. If there is a warming in temperature — even as little as 1 C — it can disrupt this relationship, causing the coral to lose its colour.

Staghorn corals killed by bleaching in the northern Great Barrier Reef. (ARC Centre for Excellence Coral Reef Studies)

The new research has found that the area worst affected is about 700 kilometres long in the northern region of the reef. That area has lost an average 67 per cent of its shallow-water coral over the past eight to nine months. 

Average coral loss along each section of the Great Barrier Reef (ARC Centre for Excellence Coral Reef Studies)

"Most of the losses in 2016 have occurred in the northern, most-pristine part of the Great Barrier Reef. This region escaped with minor damage in two earlier bleaching events in 1998 and 2002, but this time around it has been badly affected," said Professor Terry Hughes, Director of the Australian Research Council (ARC) Centre of Excellence for Coral Reef Studies based at James Cook University in a statement.

But there's also some good news.

In the southern two-thirds of the reef, the damage has been significantly less. According to Andrew Baird from ARC, in the central region, on average only six per cent of bleached corals died in 2016, with just one per cent in the south. 

Healthy coral in the Capricorn Group of Island, southern Great Barrier Reef.

Earlier this year the Great Barrier Reef Marine Park Authority (GBRMPA) said that this year's intense El Nino — a warming in the Pacific Ocean that affects climate around the globe —greatly contributed to warming sea temperatures in the region, in turn stressing the coral. It's believe that up to 50 per cent of the coral deaths were due to longer than normal above-average sea surface temperatures.


Nicole Mortillaro

Senior reporter, science

Based in Toronto, Nicole covers all things science for CBC News. As an amateur astronomer, Nicole can be found looking up at the night sky appreciating the marvels of our universe. She is the editor of the Journal of the Royal Astronomical Society of Canada and the author of several books. In 2021, she won the Kavli Science Journalism Award from the American Association for the Advancement of Science for a Quirks and Quarks audio special on the history and future of Black people in science. You can send her story ideas at