From Inside Climate News (Bob Berwyn):
Throughout the 2000s, grim reports of crumbling, pale corals multiplied, arriving from remote South Pacific atolls, the Indian Ocean, the Red Sea and, once again this year, from Australia’s Great Barrier Reef, where the overheated Pacific Ocean scalded corals for the third time in five years. The renewed bleaching of the world’s largest reef confirms that coral reefs globally are in big trouble, said scientists, many of whom reported that their dismay has been compounded by government failures to protect collapsing coral-based ecosystems despite decades of warnings.
In the Caribbean, global warming has already pushed some reef ecosystems over a climate cliff. Today’s underwater landscapes are nearly unrecognizable for scientists and divers who started visiting them 50 years ago, said University of Windsor coral reef ecologist Peter Sale.
“What we are doing to coral reefs is akin to eliminating all the rainforests on the planet,” he said. “Coral reefs are probably going to be the first globally distributed ecosystem wiped off the face of the Earth by humans.”
Corals bleach when the water they inhabit gets too warm, and they shed the pigmented algaes that provide them with food through photosynthesis. The affliction isn’t always fatal. Depending on the intensity of the event, reefs can partly recover in a decade, but lately, the waves of bleaching have come so fast that there’s no time for recovery, Sale said. Mass coral reef bleaching has become five times more common in the past 40 years, research shows.
Since the first global bleaching event in 1998 shocked coral scientists with its reach and intensity, subsequent die-offs affected reefs in regions with no known history of bleaching, including some in Hawaii. Sale said that, even if global warming is capped at the limit set by the Paris climate agreement, 90 percent of the planet’s reefs will disappear.
“Reefs are toast if we let warming get much above 1.5 degrees Celsius (2.7 degrees Fahrenheit),” he said. “I am surprised at the fact that the bleaching of coral reefs has not evoked the response from society that I would have thought. Since 1998, scientists all assumed it would be a huge wakeup call to do something. We’ve been surprised and disappointed.”
It’s not for lack of trying. The most recent key reports from the International Panel on Climate Change included stark warnings about the reef death spiral and urged immediate, significant cuts of greenhouse gas pollution to avert their annihilation.
The world’s failure to act decisively to avoid mass global coral extinctions is anguishing for Australian coral reef scientist Terry Hughes. His annual surveys of the decline of the Great Barrier Reef have led him to publicly spar with his own government and with Rupert Murdoch-owned Australian media when they downplay the damage caused by global warming or promote reef-threatening projects like the expansion of a coal-shipping terminal in North Queensland, where dredging would harm corals.