Known for its vast size, rich marine ecosystem, and brilliant coloration, the Great Barrier Reef is probably the most famous coral reef in the world. As of today, a vast swath of it has turned a sickly skeletal white. It's fallen victim to coral bleaching, a phenomenon that results when the ocean waters that reefs call home get too hot—weakening or killing off the coral altogether.
A new survey conducted by Professor Terry Hughes of James Cook University, who used charter planes and helicopters to conduct an aerial survey of the reef, found that as much as 95 percent of the northern section of the Reef—an area spanning 100,000 square kilometers (38,600 square miles)—was "severely" bleached.
Hughes flew over the reef, tweeting out pictures of the bone-white reefs alongside calls to action.
It's "the worst bleaching ever seen on what was the healthiest part of the Great Barrier Reef," Dr. Mark Eakin, the Coordinator of the National Oceanic and Atmospheric Administration's Coral Reef Watch, told me. "It's quite sad."
Australia, he says, "may lose half of their healthiest corals." He adds: "This won't be the end of the GBR but it is a huge amount of damage. The problem is that it can take decades for reefs to recover from bleaching this bad and severe bleaching is becoming much more frequent and more severe."
Richard Vevers, the CEO of the Ocean Agency, who's currently conducting a high-res underwater survey of the world's ailing reefs in conjunction with Google, says he's seen the damage firsthand, and it's bad.
"The bleaching on the Great Barrier Reef is devastating," he tells me. "It's the worst bleaching ever to hit the most pristine part of the reef."
"What we are most concerned about is that the reef won't have time to recover before next bleaching event hits."
The devastation is part of what oceanographers and marine biologists are calling the third global coral bleaching event—the longest ever recorded, according to NOAA. Record-warm waters, heated up by climate change and El Niño, are expelling the algae that corals depend on for survival. This renders them a ghostly shade of grey, and sometimes kills them altogether. And while the Great Barrier Reef is its most high profile victim, few corals will escape undamaged from the epidemic.
"For the rest of the world, this event is nowhere near over," Eakin tells me. "Many places have been hit by bleaching for two years in a row and Florida may be hit for a third year in a row." And the bleaching is only rolling on. "Right now there is bleaching across half the southern hemisphere—literally! It spans from the coast of Tanzania in the west (40° east) to French Polynesia in the east (140° west). Reports are coming in this week of bleaching throughout Indonesia."
Eakin adds that while the plight of the GBR is making headlines, there are other reefs that are currently faring even worse. The water was so warm in Fiji that it wasn't just bleaching that grew severe—fish were straight-up dying off. The inshore reefs of New Caledonia are also in deep trouble, as are those in Kiribati, where Eakin's colleagues are currently returning from an expedition with what he expects will be extraordinarily dire news.
All of which is to say: The world's reefs, one of our most colorful, vibrant ecosystems, are going white. Many are dying off. Some experts, as I've noted before, fear that this is the beginning of the end of coral itself.
The world's most famous reef isn't out of hot water yet, either. "We expect it to last through the rest of this year and could even continue into 2017 if bleaching returns to the GBR as it sometimes does after the end of an El Niño," Eakin says.
"What we are most concerned about is that the reef won't have time to recover before next bleaching event hits," Vever told me. "We are already committed to decades of continued ocean warming which will make bleaching events like this more common in the years to come."
When I asked Eakin just how dire the situation was, he responded with a two-word sentence.