El Niño worsens coral bleaching

The world’s oceans are struggling with the longest coral die-off on record. Global warming and the intense El Niño are prolonging the coral bleaching. As Barbara Barkhausen in Sydney reports, Australia’s Great Barrier Reef could also be in danger.

Global warming and the strongest El Niño on prolonging the longest mass coral bleaching on record. (Image credit: Sarah Depper, flickr/Creative Commons)

Global warming and the strongest El Niño on prolonging the longest mass coral bleaching on record. (Image credit: Sarah Depper, flickr/Creative Commons)

The third mass global coral bleaching event started in 2014, and scientists fear it could extend well into 2017. It has already surpassed the previous largest global bleaching events of 1998 and 2010.

Hawaii and Fiji hit two years in a row

“We are currently experiencing the longest global coral bleaching event ever observed,” said Mark Eakin, NOAA’s Coral Reef Watch coordinator. “We may be looking at a two- to two-and-a-half-year-long event.” Some areas such as Hawaii have experienced bleaching two years in a row.

Fiji, which was recently in the news because of the devastating cyclone Winston, has also been hit hard, and warmer water temperatures are killing of coral and fish alike. Like Hawaii, the Pacific island nation was affected by coral bleaching last year, too.

Stressed by warmer waters

According to NOAA, coral bleaching occurs when corals are stressed by conditions such as high water temperatures. When ocean temperatures repeatedly rise, corals in some parts of the world have no time to recover before they experiencing more bleaching. Recurrent exposure to bleaching will cause corals to die.

Coral die-off causes reefs to erode, destroys fish habitats and makes once-protected shorelines vulnerable to the destructive force of waves.

Strongest El Niño on record

The current El Niño is worsening an already dramatic situation. Over the past few months, the weather phenomenon – which causes extreme drought and heat waves for the Pacific Rim in the west and rain and flooding in the east – has increased surface water temperatures in the southeast Pacific by more than 0.5 degrees on average.

According to the Australian weather bureau, the current El Niño has tied the one in 1997-1998 as the strongest on record. Back then, temperatures rose so dramatically that 15 per cent of global coral reefs died off.

Great Barrier Reef in danger

Australia’s Great Barrier Reef, with its 3,000 individual reefs, 1,500 fish species and 400 types of coral, has been spared until now. But scientists fear that it could be in danger as warmer ocean temperatures make their way to Australia. “It’s crunch time for the Great Barrier Reef,” Tyrone Ridgway of the University of Queensland told the Australian edition of the Guardian.

He and his colleagues are hoping for bad weather. Clouds and rain could help keep temperatures at bay and spare the Great Barrier Reef, which has already lost half of its coral reefs over the past 30 years.

The UNESCO site is also under threat from coal port expansions and crown-of-thorns starfish, as well as heavy storms and agricultural run-off. Scientists hope that the 1997-1998 El Niño does not foreshadow what is yet to come: it affected half the reefs on the Great Barrier Reef.

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