Arlington Reef in Queensland, is part of the Great Barrier Reef. — LUKA PETERNAL/Wilkimedia Commons
Researchers at the Australian Institute of Marine Science observed record coral regrowth this year along two-thirds of the Great Barrier Reef’s expanse. It’s the largest growth in 36 years of official monitoring, and it’s great news.
But it’s a problem that the regrowth was necessary at all. Without repeated heat-driven coral bleaching – four episodes in seven years – the reefs wouldn’t have needed to bounce back. Heat can chase off the algae that thrive on corals and give them their colour – hence “bleaching” – or kill the coral outright at high enough temperatures.
And while the recovery is a welcome headline, the same annual report of reef conditions warns that “there is increasing concern for its ability to maintain this state.”
A study published recently in the journal PLos Biology refined the point: When multiple threats to reefs – heat waves, storms, acidification, pollution run-off – are considered at the same time, half the world’s coral face real danger by 2035.
Climate scientists warned this year that coral bleaching has “induced measurable reef grief” among researchers and also tourists, who increasingly visit the Great Barrier Reef as a form of “last-chance tourism”.
The Great Barrier Reef is actually a network of 3,000 smaller reefs that parallel the coast of Queensland. Reef-related tourism employs an estimated 64,000 people and brings in US$4.4bil (RM20.85bil). Australia’s reefs host 600 kinds of coral and 12,000 animal species.
“Most climate models predict that the Great Barrier Reef will start seeing bleaching events, essentially every year, beginning sometime around 2040 to 2050,” says Derek Manzello, who leads the US National Atmospheric and Oceanic Administration’s Coral Reef Watch, a programme that draws on satellite images to monitor reef health in real time.
“So it’s very concerning for us that we’re getting close now.”
Imogen Zethoven, director of Blue Ocean Advisory, has continually returned to the site over her career, not only for the beauty but also because of the problems. “It’s a bit like a country,” she says. “It brings so many different issues together – environmental issues, economic, social issues. And it’s incredibly complex. It’s probably the size of Italy or Japan. (People) don’t understand how big it is until you say that.”
Conserving the reef has long been a source of national pride for Australia, which has committed more than US$2bil (RM9.48bil) in science and efforts to slow the damage, by cutting agricultural run-off that leads to coral-killing crown of thorns starfish infestations, developing the coast in a way that avoids harming reefs and other means. The country has also limited some industrial fishing techniques.
Yet the surest way Australia could save its reefs is to eliminate the emission of heat-trapping gasses as soon as possible and lead every other nation to do the same. The current government, led by centre-left Prime Minister Anthony Albanese, broke decisively with the policies of his predecessor, Scott Morrison, who played down or dismissed climate risks. The nation’s coal and mining industries have long pushed back at aggressive climate policy. That may be changing, as Albanese pushes for enactment of laws to clean up Australia’s industry and cut emissions.
Decades of accelerating heat have taken a cumulative toll on the Great Barrier Reef. A powerful El Niño in 1998 fuelled that year’s coral die-off and led to projections that such an extreme event would probably “become commonplace within 20 years”. The last eight years have been the hottest on record.
Oceans absorb heat like a kitchen sponge does water, and corals die off when water temperatures exceed their normal maximum by about 1°C. Within 20 years of the 1998 episode, the Great Barrier Reef entered a new era of heat-induced damage. A 2016 bleaching affected 90% of the reef, wiped out half the northern region and shrunk coral cover by 30% overall.
More bleaching came the next year, then again in 2020 – and again this year.
It’s a global phenomenon. Dozens of researchers are compiling a study of coral bleaching between 2014 and 2017. They estimate in a pre-peer-review draft that half the world’s coral reefs saw severe bleaching and 15% significant die-off. “Global warming’s widespread damage to coral reefs is accelerating,” they write.
This year brought bleaching-level heat, but it didn’t kill the coral like it did in 2016. And, in an unsettling portent for the future, it came during a La Niña, or cooling, phase in the Pacific – something that likely could never have happened without temperatures 1.2°C higher than pre-industrial times. Australia has warmed at least 0.2°C faster than the rest of the world.
Efforts to re-grow corals and restore reefs are relatively new and limited to short-term time frames over small areas.
“I don’t hear anyone saying that we could restore the Amazon by growing trees in greenhouses,” says Terry Hughes, a professor at James Cook University in Queensland. “The barrier reef is the size of 70 million football fields, and globally in the last 50 years maybe we’ve restored – and there’s issues around what’s the definition of restoration – maybe two football fields globally.”
The dark long-term trend for the Great Barrier Reef “doesn’t mean to say that you can’t hop on a boat and go and see a beautiful reef”, Zethoven says.
“But when you look at the scientific projections, and you look at where the world is heading with their policies and their pledges, and the actual performance, it doesn’t generate a great deal of hope,” he adds.
Discovering a promising way forward requires more than hope. It requires training. The Great Barrier Reef “will never behave functionally the way it did 30 years ago, at least not in our lifetimes,” Hughes says.
“There’s never been a more important time to be a marine biologist.” – Bloomberg
