The past few months have brought another rough summer for the Great Barrier Reef, which is suffering a major bleaching event for the second year in a row.
Australian coral reef experts made that conclusion after flying over the Great Barrier Reef for six hours yesterday, according to a press release issued by the Australian government’s Great Barrier Reef Marine Park Agency (GBRMPA). Coral can survive bleaching events, but rising sea surface temperatures have caused some to worry about the long term outlook for these biodiverse regions.
The Great Barrier Reef is the world’s largest reef and “largest living structure,” a 2300-kilometer (almost 1500-mile) expanse of colorful coral off the eastern Australian shore, hosting thousands of species of fish, mollusks, jellyfish and other sea creatures. These coral rely on microscopic algae embedded in their tissue to produce food via photosynthesis. But if the water gets too warm or polluted, those algae can be expelled. The starving coral then turns bone white and becomes more susceptible to disease. If the coral dies, it will turn a nasty greenish-brown as other opportunistic algae grow on its surface.
Last year’s warm water brought coral bleaching events worldwide, which were made worse by the El Niño climate pattern, according to a story published last year in the Guardian. This year’s reports are fairly unsurprising—we’ve basically been experiencing the same continuous global coral reef bleaching event since 2014, Mark Eakin, Coordinator of NOAA’s Coral Reef Watch program explained to Gizmodo.
Great Barrier Reef Marine Park rangers started receiving reports back in January, the start of Australia’s summer, that the coral wasn’t looking too good this year. By February, corals were starting to show signs of stress from elevated water temperatures. Yesterday’s survey of the central third of the Reef’s length revealed severe bleaching; this area largely escaped last year’s event, according to the GBRMPA.
The problem with years of successive bleaching is that corals have little time to recover in between. And as much as some American readers might hate to read this, climate change is likely a major factor. Australian authorities have pointed to carbon emissions as the probable cause, and have cited cutting emissions as the best solution to fix their ailing coral reef.
“It’s vital the world acts to implement the Paris Agreement to reduce greenhouse gas emissions,” said Marine Park Authority Director of Reef Recovery David Wachenfel in the press release.
But even the Paris Agreement might not even be enough to save corals. “You may remember the Paris Agreement talks about staying under 2 degrees of warming,” said Eakin, with an aspirational goal of keeping below 1.5 degrees of warming. “The probem for coral is that 1.5 degrees is all the they can handle. We’re already up one degree and look what’s already happening.”
On top of climate change, more local issues threaten reefs, Eakin explained. “In many areas, people are causing declines in coral reefs because of pollution, overfishing, and habitat destruction,” he said. “We have to be reducing the amount of CO2 in the atmosphere and addressing the local stressors so the coral can have the best chance to survive.”
The GBRMPA will send scientists and experts to survey the remaining length of the reef later this month. Regardless of what a few important Americans may think, human carbon emissions will continue to be to blame as coral continue to suffer from increased bleaching events and ocean acidification.
“According to the study’s lead author, Professor Terry Hughes from the Australian Research Council Centre of Excellence for Coral Reef Studies at James Cook University, “The severity of the 2016 bleaching was off the chart”, and more severe than the two previous major bleaching episodes on the Great Barrier Reef in 1998 and 2002.”
The recent bleaching events were likely due to high ocean temperatures, and past events didn’t help corals build immunity against future bleaching. So, all in all, things are still bad.