Half of Great Barrier Reef corals have died: study
October 14, 2020
Climate change is cited as the key reason for the death of the corals. The authors of the study said that the ability of the Great Barrier Reef to recover is compromised.
Image: University of Bristol/Isla Keesje Davidson
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Around 50% of Australia's Great Barrier Reef has died since the 1990s, according to a study published in the Proceedings of the Royal Society Journal.
"The decline occurred in both shallow and deeper water, and across virtually all species — but especially in branching and table-shaped corals. These were the worst affected by record-breaking temperatures that triggered mass bleaching in 2016 and 2017," said Professor Terry Hughes, co-author of the study. Loss of table-shaped corals will also reduce fish abundance.
Hughes added that the Great Barrier Reef's ability to recover was compromised as there are fewer large breeding corals.
"A vibrant coral population has millions of small, baby corals, as well as many large ones — the big mamas who produce most of the larvae," he said.
"Our results show the ability of the Great Barrier Reef to recover — its resilience — is compromised compared to the past, because there are fewer babies, and fewer large breeding adults," he added.
Doomsday tourism and climate change: Visiting natural wonders before they disappear
From the Great Barrier Reef to majestic glaciers, increasing numbers of tourists are vacationing in places expected to succumb to climate change before it's too late.
Image: picture-alliance/McPhoto/SBA
Transient treasure
Of the 2 million-odd people who visit the Great Barrier Reef annually, a 2016 survey found that 69 percent were coming to see the UNESCO World Heritage site "before it's too late." And no wonder. The IPCC says that even if we manage to limit global warming to 2 degrees Celsius, 99 percent of the world's coral will be wiped out. Tourists can hasten their demise by touching or polluting reefs.
Image: picture-alliance/dpa/N. Probst
Bearly there
And what's the carbon cost of flying to remote natural wonders under threat? A 2010 study found that the business of polar-bear safaris in Churchill, Canada, had an annual CO2 footprint of 20 megatons. Most visitors arrived by plane, and while 88 percent of them said humans were responsible for climate change, only 69 percent agreed that air travel was a contributing cause.
Image: picture-alliance/McPhoto/SBA
Art of the apocalypse
Along with the polar bear, one of the most iconic images of climate change must be the dramatic curves of an iceberg sculpted by the warming atmosphere. Gliding between the melting giants on a cruise ship is a haunting experience that tourists will pay huge sums for. In the early 1990s just 5,000 people visited Antarctica each year, compared to over 46,000 in 2018.
Image: S. Weniger/M. Marek
Peak season
You don't have to go to the poles to see vanishing ice. Kilimanjaro's snowy peaks are a striking sight above the equatorial savannah of the national park, which generates €44 million ($50 million) from tourism annually. Many visitors climb to the Furtwängler Glacier — where 85 percent of the ice has vanished over the last century. The rest is unlikely to survive much beyond mid-century.
Image: picture-alliance/dpa/R. Schnoz
King without a crown
When Montana's Glacier National Park opened in 1910, it boasted over 100 of the ice features from which it took its name. Now, there are fewer than two dozen. So dramatic is their retreat, that the park has become a center of climate science research. Some 3 million hikers and holidaymakers also visit the "crown of the continent" each year, soaking in the dying days of its ice-capped glory.
Image: Imago Images/Aurora/J. Miller
Paradise lost
The Maldives are the archetypal tourist paradise: 1,200 coral islands with white beaches rising just 2.5 meters above the turquoise waters. In 2017, the president decided to build new airports and megaresorts to accommodate seven times as many tourists, and use the revenue to build new islands and relocate communities. He has since been voted out of office and faces corruption charges.
Image: Colourbox
Saltwater swamps
It's not just islands that are going under as sea levels rise. Wetlands like Florida's Everglades are disappearing too. Over the last century, around half the Everglades have been drained and turned over to agriculture. Now, saltwater is seeping into what's left, making it the only critically endangered World Heritage site in the United States.
Image: Imago/Robertharding/F. Fell
Disturbing the peace
The Galapagos will be forever associated with Darwin, who realized their unique wildlife had evolved over countless generations in isolation. Today, they are besieged by visitors and environmental changes are happening too fast for species to adapt. Ocean warming has left iconic creatures like the marine iguana starving, while UNESCO lists tourism among the greatest threats to the archipelago.
Image: picture-alliance/dpa/R. Kaufhold
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Climate change killing the corals
The Great Barrier Reef is the world's most extensive coral reef ecosystem and the habitat of threatened species such as the dugong and large green turtle.
The death of the corals has been attributed to ocean warming, which is fueled by climate change. Changes in ocean temperatures stress healthy corals, causing them to expel algae, which drains them of their vibrant colors. This process is called bleaching.
The reef also been affected by several cyclones and two outbreaks of crown-of-thorns starfish, which eat the coral.
The authors of the study warned that greenhouse gas emissions had to be reduced immediately to save the corals.
"It takes about a decade for a half-decent recovery for the fastest-growing species, so the chances of us getting decades between the future sixth, seventh and eighth bleaching events is close to zero because temperatures are going up and up and up," said Hughes.
The authors of the study also said that to further understand changes in coral populations and their recovery from disturbances, detailed demographic data on recruitment, reproduction and colony-sized structure was needed.
