Global Coral Bleaching Event
Coral bleaches when water temperatures are a couple of degrees above the normal summer maximum for longer than about two weeks. According to the Guardian:
“Bleaching occurs due to abnormal environmental conditions, such as warmer sea temperatures. When waters warm beyond what coral can cope with, they expel the algal squatters that feed them energy and give them their brilliant colours, leaving them white and weak. If that lasts too long, the corals starve, become infected with viruses, and die.”
– Michael Slezak
Coral reefs can often recover from bleaching when there is enough time between bleaching events, provided there aren’t too many other stressors, such as overfishing and water pollution. But the reef is already under pressure from farming run-off, development, the coral-eating crown-of-thorns starfish as well as the impacts of climate change.
Climate change has caused global sea surface temperatures to rise by about 1C over the past century, pushing corals closer to their bleaching threshold.
“Research shows that the frequency of mass bleaching events is increasing because of global warming. The corals are being hit again and again,” says Mark Eakin, coordinator of the Coral Reef Watch program at the US National Oceanic and Atmospheric Administration. “The big problem with that is that coral reefs need time to recover. If they get hit too frequently, they can disappear, being taken over by algae and seaweed.”
The world’s largest global bleaching event started in 2014 and is the longest event of it’s kind in history due to a strong El Nino weather pattern throughout 2015 and 2016. Mark Eakin was hopeful the current global bleaching event would end in 2017, but said it was possible it would just roll on, alternating between the northern and southern hemispheres as the seasons changed.
“At some point, we’re probably going to hit that level [of global warming] where it doesn’t go away and it’s continuous,” Eakin said. “The climate models have been saying for well over a decade that we’re looking to sometime around the 2020s where global bleaching becomes the norm.”
Every major reef region was hit and some areas like Hawaii have been hit 3 years in a row. Some reefs around Guam had been hit for a fourth year in a ro3 and 93% of the Great Barrier Reef was affected by bleaching. By the end of 2015 38% of the world’s reefs had been affected and bout 5% will have died forever.
The world is more aware of Global Warming now than ever before as countless tipping points have now been reached and tackling it head-on is vital. Since the early 1980s the world has lost roughly half of its coral reefs. I think it is important for people to see these changes with their own eyes because it is truly humbling what humankind has done to the world – humbling and frightening. So it’s a very motivating influence in changing people’s habits in the way they live.
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