The Great Barrier Reef has weathered back-to-back mass bleachings over the past two years. Battered by the effects of climate change, it's dying at a rate scientists didn't expect for 30 years. Aerial surveys show some 83 percent of corals in the reef's north have been affected by bleaching. And, according to 46 top reef scientists, it's unlikely the reef will have time to recover before summer potentially brings more bleaching.
It's worth knowing a little about why these bleaching events are so devastating: they happen when the reef expels a microscopic algae called zooxanthellae that lives inside it. The reef needs the energy created by this algae's photosynthesis to survive. But when it's stressed—such as by rising temperatures and ocean acidification—expelling the zooxanthellae is the reef's go-to response.
Obviously, this is not a new story: everyone knows the climate change is killing the Great Barrier Reef. However, this week the World Heritage Committee decided not to add the reef to its "in danger" list. Instead, it released a statement saying the committee "welcomes the progress made with the inception and initial implementation of the Reef 2050 Long-Term Sustainability Plan (2050 LTSP) and… expresses its appreciation for the significant efforts by all those involved in the implementation of the 2050 LTSP."
Jon Day, from James Cook University's ARC Centre of Excellence for Coral Reef Studies says he's not surprised by the committee's decision. Having worked on the Great Barrier Reef for decades, he's seen the devastating impacts of climate change—but he's also been to 11 of these World Heritage Committee meetings, and even acted as Australia's representative on a number of occasions.
"They are concerned about it but they didn't just want to come in and list it as 'in danger,'" Jon explains, pointing out the committee "notes with serious concern" the mass bleaching events in 2015 and 2016. "We've seen a level of coral mortality that we're not going to see the reef return to how it was. Our kids aren't going to see the reef as we saw it."
But as he adds, "an 'in danger' listing isn't going to fix the problem."
The problem, of course, is climate change. On paper, both the Australian Government and the World Heritage Committee accept that "climate change remains the most significant overall threat to the future of the [reef]." However, there's very little in Australia's Reef 2050 Long-Term Sustainability Plan to directly address climate change. When it was released, many conservationists criticised the plan for focusing instead on lesser threats, such nitrogen run-off and crown of thorns starfish outbreaks.
But the government's view, noted in the 2050 LTSP, is that climate change is a global problem that "requires a global solution." Jon Day agrees with this, but says there are "dramatic reductions required in CO2 emissions" if we want the reef to live. This view is backed up by the World Heritage Committee, which released a report last week saying that, without drastic action, all of its World Heritage listed coral reefs are likely to die by the end of this century.
"Soaring ocean temperatures in the past three years have subjected 21 of 29 World Heritage reefs to severe and/or repeated heat stress, and caused some of the worst bleaching ever observed at iconic sites like the Great Barrier Reef (Australia), Papahānaumokuākea (USA), the Lagoons of New Caledonia (France), and Aldabra Atoll (Seychelles)."
Yet the committee's decision on the Great Barrier Reef didn't mention the Carmichael coal mine project, which will be Australia's biggest ever coalmine and is strongly supported by the Government. Conservation groups say burning the coal from the mine could singlehandedly push the world above the two degrees of global warming if it goes ahead—which could be catastrophic for the Great Barrier Reef. As UNESCO notes, "It only takes a spike of 1-2°C to cause bleaching."
"If it goes ahead: that's the $16 billion question," Jon says of the Carmichael mine. "There's no doubt though that anything that's going to cause carbon emissions is going to have an effect, not only the Great Barrier Reef, but also on reefs all around the world."
Australian minister for environment and energy, Josh Frydenberg, took a more optimistic view of the World Heritage Committee's decision. "This is a big win for Australia," he said. "We're taking every action possible to ensure this great wonder of the world stays viable and healthy for future generations to come… [and] we've received a strong endorsement that our Reef 2050 Plan is working."
Follow Maddison on Twitter