The Great Barrier Reef has been hit by back-to-back cases of coral bleaching over 2016 and 2017, causing scientists to fear for its future. According to an aerial survey conducted by the James Cook University’s ARC Centre of Excellence for Coral Reef Studies in Queensland, 900 miles out of 1,400 miles of the reef have been bleached due to higher water temperatures. More concerning to scientists is the fact that unlike 2016, 2017 was not an El Nino year, during which scientists can expect warmer water temperatures.
The survey examined 800 separate reefs in the Great Barrier Reef and found that compared to last year’s bleaching, bleaching in 2017 had expanded further south.
Professor Terry Hughes, the center’s director and one of the lead scientists, said in the Washington Post that he predicted a loss in 2017 similar to 2016, where scientists “lost 67 percent on average of the corals in the northern 700 kilometers (430 miles) of the barrier reef, between March and October.”
According to the Guardian, only the southern third of the reef remained unbleached in the findings from 2016 and 2017.
Hughes commented to the Guardian, “The significance of bleaching this year is that it’s back to back, so there’s been zero time for recovery.”
The Great Barrier Reef previously faced bleaching episodes in 1998 and 2002, giving the reef four years in between to recover. However, even those years were uncomfortably close together as coral reefs usually take at the least 10 years to fully recover from a bleaching. Hughes noted in the Washington Post that since the first bleaching in 1998, the planet has warmed 1 degree Celsius.
Extensive bleaching episodes can cause coral reefs to die out, a worst-case fear for the Great Barrier Reef. However, Hughes told the Washington Post that he “wouldn’t say the barrier reef is dying. But clearly, we’re measuring serious losses here. And the reason it’s happening is global warming.”
Scientists believe the oceans water temperatures will continue to rise due to global warming, and likely surpass 1.5 to 2 degrees Celsius, putting even more pressure on the future of the reef.