An aerial survey of the northern section of the Great Barrier Reef has bleak news: 95 percent of the region is now “severely bleached.” The finding comes just weeks after news that worldwide record-breaking temperatures have spurred widespread bleaching of the northern reef. At the time, the severity was not known. Now, a survey team says the situation is critical.
“This will change the Great Barrier Reef forever,” Professor Terry Hughes of James Cook University told local ABC radio station 7.30. “We're seeing huge levels of bleaching in the northern 1,000-kilometer (620 miles) stretch of the Great Barrier Reef.”
While bleaching can be triggered by a variety of factors, researchers are definitive on the cause for this reef section, which extends from Cairns to the Torres Strait: “What we're seeing now is unequivocally to do with climate change,” said Professor Justin Marshall, a reef scientist from the University of Queensland.
— Terry Hughes (@ProfTerryHughes) March 24, 2016
Hard corals are chemists of simplistic solutions: They combine CO2 with seawater to construct exoskeletons made of calcium carbonate. In doing so, they form finger-like coral, sponge-like coral, tree-like coral – the list goes on and on. Unfortunately, global warming has decimated both hard and soft coral reef communities by raising the temperature of their aquatic habitat, turning them from neon-colored treasures into ghostly white sticks.
Of the 520 reefs the researchers examined, only four remained unbleached. Yet the previous conditions of the once-colorful ribbon reefs – deemed one of the most pristine coral regions in the world – could work to its advantage. If environmental conditions improve and sea temperatures cool (as can happen during winter months), this region has a greater chance of bouncing back. However, it is important to note that with each bleaching event, the overall health of the coral weakens.
“It's important to remember that bleaching doesn't mean a coral dies,” Dr. Tyrone Ridgway told IFLScience a few weeks back. “It's only if the heat stress persists that we see mortality.” As of now, though, the outlook is not good.
There is some good news, however, for the southern and central regions of the Great Barrier Reef. “The bottom three-quarters of the reef is in strong condition,” said Hughes. “[But] as we head north of Lizard Island it becomes increasingly prone to bleaching.”
In-water surveys are now planned to gauge the exact extent of bleaching in the northern region.