Even to the untrained eye, it’s easy to see that the Great Barrier Reef is in more than a little hot water.
As I board my charter flight from Cairns bound for the remote scientific research station on Lizard Island, I mentally prepare myself for devastating scenes.
Climbing steeply, we bank sharply to the right – and soon the tropical green of Queensland’s northern coast is replaced by a startlingly bright turquoise sea.
It doesn’t take long for my fears to be realised. I look down at an opalescent sea awash with white. Reefs that were once among the world’s most unspoiled now languish under a baking sky, every one seemingly bleached.
My pilot turns and gives me a thumbs down, shaking his head sombrely.
Worst on record
This is the worst bleaching event the Great Barrier Reef has ever seen, according to Terry Hughes, director at the ARC Centre of Excellence for Coral Reef Studies in Townsville, Queensland.
Bleaching happens when corals become stressed and expel algae called zooxanthellae living inside them. These colourful algae provide up to 90 per cent of the energy needs of corals through photosynthesis. Corals can survive bleaching, but will die if they stay in that condition for long enough.
This year’s bleaching has been linked to the strongest El Niño event on record and climate change, both of which are driving up ocean temperatures here.
“One of the impacts of El Niño here in Australia is a weaker monsoon,” says Andrew Watkins, manager of climate-change prediction services at the Australian Bureau of Meteorology. “For the reef, that means less cloud and more sunny days.”
This puts more heat stress on corals, leading to bleaching, which has been getting progressively worse.
“It’s already very clear that what we are seeing here is much greater than back in 2002, which in turn was greater than 1998,” says Hughes.
He lays the blame firmly at the door of climate change. “The baseline of sea temperature is going up decade by decade due to global warming. When an El Niño event comes along, it adds an extra spike to that rising baseline. We’ve always had those spikes, but before global warming they didn’t cause the damage that they do now.”
This is my first visit to the reef, and it’s not looking good… at all.
Home to some 1500 species of fish, 411 types of hard coral and a third of the world’s soft coral, the reef is the largest living structure on the planet.
Its sheer magnitude makes the reality of surveying it neither quick nor simple: it covers an area bigger than the UK, the Netherlands and Switzerland combined.
Hughes first focused his aerial surveys on the reef’s northernmost section, which was the hardest-hit area. He concluded recently that 95 per cent of it had been “severely bleached”.
“It was the saddest research trip of my life,” says Hughes, who is yet to find a southern boundary to the bleaching.
“Initially I thought we’d only have to survey the most northern part,” he says. “It’s clear though that this bleaching is much more extensive than we thought.”
In 2002, just 18 per cent of reefs in the Great Barrier Reef – 120 in total – were severely bleached. This year, well over 500 reefs have been affected so far. “This is much more severe than anything we have seen before,” says Hughes.
It could be another six to eight weeks before we get a full picture of how much coral has been lost.
Researchers are keen to find out how multiple bleaching events are affecting the corals.
It takes around 10 years for faster-growing corals to recover from bad bleaching, says Ove Hoegh-Guldberg of the University of Queensland in Brisbane. “We could be getting close to a scenario where the return time for bleaching is actually shorter than the recovery period, and that would be a recipe for ever-declining coral cover.”
Among the corals
On Lizard Island, the research station lies a stone’s throw from the shortest landing strip I’ve ever seen. I’m picked up in a classic 1990s white land cruiser and 10 minutes later, after bumping along a short sandy track, I arrive at the research station, which provides accommodation, dive boats, laboratories, a full aquarium and scuba equipment.
“The amount of coral being affected by this year’s bleaching is mind-boggling,” says Lyle Vail, one of the station directors. “You see corals that you’re familiar with, have swum with and that you know individually, and now they are dying.”
And he says that with soft corals, which lack the skeleton of hard corals, only bare rock is left once they’re gone. “You’d never even know they were there. It’s devastating,” he says.
I dive alongside a team of documentary film-makers, among once-pristine coral that’s now dying before our eyes. A single word is enough to describe our emotions as we head back to base: heartbreak.
It’s hard to imagine how the reef – held up as a bastion for those around the world – can fully bounce back. The hope for many of the scientists is that this event will at least communicate to a global audience the reality of climate change and the effects it’s having on the natural world.
“Coral cover on the Great Barrier Reef could look very different 10 years from now,” says Hoegh-Guldberg. He highlights that 50 per cent of its coral cover has been lost in the past 30 years and predicts a further decline of 20 per cent if we continue on this path.
“If we don’t take aggressive action on climate change over the next decade, it will essentially mean the end of coral-dominated paradises like the Great Barrier Reef and intact coral reefs across the world,” he says.
Read article at New Scientist