australia's famous Great Barrier Reef has suffered one of the most severe coral bleaching events on record, and scientists are worried about their survival as the effects of climate change worsen.
Marine biologist Anne Hoggett has lived and studied Lizard Island, a small piece of tropical paradise on Australia's northeastern tip, for 33 years.
She affectionately calls it “Blizzard Island.” The only relief from the wind and pouring rain is the powder blue waters along the Great Barrier Reef, teeming with sea turtles and tiger sharks.
As the hogget snorkels, schools of fish gracefully swim by, feeding on the coral or jumping among it. Some are as small as her little finger, others the color of flames.
But thanks to climate change, it is becoming a watery graveyard for bleached coral reefs.
“We don't yet know if they've already been irreparably damaged,” Hoggett said.
The world is currently experiencing its second major coral bleaching event in a decade, the National Oceanic and Atmospheric Administration (NOAA) announced Monday.
Coral bleaching occurs when water temperatures rise above 1 degree Celsius (33.8 degrees Fahrenheit).
“As the world's oceans continue to warm, coral bleaching events are becoming more frequent and severe,” said NOAA's Derek Manzello.
To survive, corals excrete microscopic algae known as zooxanthellae, which they need to survive.
If high temperatures persist, the coral will eventually expel most of the zooxanthellae, turning white and dying.
Since February, seawater temperatures around Lizard Island have been up to 2°C warmer than average.
Hoggett estimates that about 80 percent of the coral is already dead.
“Almost everything died.”
The Great Barrier Reef, the world's largest living structure, spans 2,300 km and is home to incredible biodiversity, including more than 600 species of coral and 1,625 species of fish.
This is vital to ocean health and Australia's tourism industry, generating billions of dollars in revenue each year.
However, repeated large-scale bleaching events have diminished the coral reef's beauty, turning the once vibrant coral banks a sickly gray-white color.
In March, Australian coral reef authorities announced that another major bleaching event was underway, the fifth in eight years.
Through aerial monitoring, more than 600 coral reefs were found to be bleached.
Ten percent of the area has experienced severe bleaching, and more than 90 percent of the corals are damaged and unlikely to survive.
Just nine weeks ago, the reef off Lizard Island was healthy and vibrant, Hoggett said.
Now she pointed to the fluorescent pink and blue coral. Despite their initial beauty, that means the corals are under great stress and are shedding the healthy algae they need to survive.
Elsewhere, white coral is covered with fluffy brown algae, indicating that the coral is dead.
When Hoggett first arrived on the island 30 years ago, bleaching events occurred about every 10 years. It is now held every year.
Large-scale bleaching events along coral reefs have occurred in 1998, 2002, 2016, 2017, 2020, 2022, and now in 2024.
She is heartbroken.
“The only time we saw bleaching this bad was in 2016, when almost everything died,” Hoggett told AFP.
“No one knows how many of the corals still alive will survive and recover.”
“The scale is too small”
Coral reefs can recover from bleaching, but the recovery window between bleaching events is narrowing.
As the world continues to warm, it is predicted that if temperatures rise by approximately 2 degrees Celsius, the world's coral area will decrease by 95% due to bleaching events.
Bleaching will increase by 70% if temperatures increase by up to 1.5 degrees Celsius above pre-industrial levels.
Even if all countries fulfilled their climate change commitments, the world would still warm by more than 2 degrees Celsius.
Globally, billions of dollars are being poured into coral bleaching mitigation projects, such as breeding and relocating corals on artificial reefs, increasing the thermal reflectivity of clouds, and controlling coral predators. ing.
While these site-specific conservation efforts are important, Terry Hughes, one of Australia's leading coral reef scientists, says they do nothing to address the root cause of bleaching: climate change.
“After 50 years of intervention, coral restoration attempts have not resulted in changes to the ecology of any reef anywhere,” Hughes said. “It's too small.”
For example, there are strict restrictions on coral breeding in aquariums, Hughes said.
“Increasing coral cover on the Great Barrier Reef by just 1 percent would require 250 million large corals the size of dinner plates, which would cost billions of dollars,” he said. added.
“The solution is to reduce greenhouse gas emissions as quickly as possible.”
“to not give up”
Australia is investing approximately A$5 billion to improve water quality, reduce the effects of climate change and protect endangered species.
The country is one of the world's largest exporters of gas and coal, and only recently set modest targets for carbon neutrality.
Whether these efforts are sufficient to maintain the coral reef's World Heritage status will be considered by UNESCO later this year.
Great Barrier Reef Marine Park Authority chief scientist Roger Beeden said it would take time for this year's event to fully materialize, but he was hopeful the corals would recover.
“There are hundreds of species of coral and they have evolved in incredibly dynamic environments. They are extremely adaptable,” he said.
“We need to do everything we can. I always have hope. I think like a doctor – I'm not going to give up on this patient.”
On Lizard Island, Hogget worries about the future of the island.
“Coral reefs are so beautiful and I love them so much. They do so much good for the world,” she said.
“It's within our power to stop this from happening, and I'm just angry that we're not doing something fast enough.”
Written by Garyn Lambly ©Agence France-Presse
