The Great Barrier Reef coral bleaching reaches ‘tipping point’

According to numerous experts, the Great Barrier Reef could set off a global bleaching event, dooming life on a massive scale.

 

 

The US government’s National Oceanic and Atmospheric Administration (NOAA) has anticipated that the Great Barrier Reef is on the verge of the largest event of coral bleaching yet seen.

Dr William Skirving from NOAA’s Coral Reef Watch suggested that “2020 is likely to be the most extensive coral bleaching event that we have seen so far”. Dr Skirving told Guardian Australia to expect very few reefs without some bleaching.

The impending phenomenon can already be observed, with pockets of bleaching in areas such as Lizard Island, north of Cooktown, and more than 1,100 kilometres south-east at Heron Island, off the coast of Gladstone.

Earlier this month also saw the Great Barrier Reef Marine Park authority, conservationists and scientists all warning that heat stress was building along with the majority of the reef 2,300-kilometre reef in Queensland, and that temperatures would need to drop over the coming two weeks if the reef is to avoid the third mass bleaching event in five years.

 

Large-scale bleaching events have increasing in frequency, and while the Great Barrier Reef can technically “bounce back” from such incidents, there is concern that individual reefs will not have enough time to recover between each occurrence.

 

The silver lining (if you can call it that) is that, while the bleaching could impact the entirety of the reef, the damage is expected to be less intense than that of previous major bleaching outbreaks. In 2016 and 2017, back-to-back bleaching events killed almost half of the reef’s corals.

“I’m expecting a bit of mortality, but I don’t think this will get to the levels where we have seen large-scale mortality,” said Skirving.

Coral bleaching occurs when the coral inhabits unusually warm waters for extended periods of time. The algae that serves as a food source and the coral’s colour separate from the animal, leaving behind a white skeleton of what once was. 

Coinciding with unusually high ocean temperatures (which can kill corals almost immediately on their own), this time period will see weaker tides, reducing the mixture of waters that help dissipate heat through the water column. Dr Skirving mentioned that only a significant weather event, like that of a cyclone, would limit the process.

Large-scale bleaching events have increasing in frequency, and while the Great Barrier Reef can technically “bounce back” from such incidents, there is concern that individual reefs will not have enough time to recover between each occurrence.

Dr Mark Eakin, coordinator of Coral Reef Watch at the National Oceanic and Atmospheric Administration, today told The Guardian that the mass bleaching seen along the length of the Great Barrier Reef in 2020 could mark the start of another global-scale bleaching event.

“The real concern is with this much bleaching without tropical forcing,” Eakin said. “This may be a sign we’ve now tipped over to near-annual bleaching in many locations.”

“It’s quite concerning that we are getting this much heat stress across the Great Barrier Reef in an Enso -neutral year.

“What we are seeing on the Great Barrier Reef and potentially elsewhere is really being driven just by anthropogenic climate change.

“If we get another El Niño, the odds are almost 100% that we will see another global bleaching event.”

 

 

 

 

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