Great Barrier Reef: Severe coral bleaching hits two-thirds of reef, aerial surveys show

Updated

Two-thirds of the Great Barrier Reef has now been devastated by severe coral bleaching, with the most intense damage occurring further south this year, Queensland scientists say.

Key Points: Of the 2,300km of reef, 1,500km is bleached

Middle third section has most intense bleaching, southern third unscathed

Caused from record-breaking temperature

The fastest growing coral will take a decade to recover

An aerial survey of the reef's 2,300-kilometre length by the Australian Research Council's Centre of Excellence for Coral Reef Studies showed 1,500km had been bleached.

Compared to its 2016 survey, where the northern third was worst off, this year the central third — Cooktown down to Townsville — recorded the most intense bleaching.

The southern third is unscathed.

The council's director, Terry Hughes, who undertook the aerial survey both years, said record-breaking temperatures, driven by global warming, has led to the bleaching.

He said it would take the fastest growing coral in the 1,500km stretch about a decade to recover.

"The 10-year recovery hasn't even started yet, because of the back-to-back bleaching," he said.

"There has been no gap in bleaching between 2016 and 2017, we need gaps between bleaching to get a full recover."

Dr James Kerry from James Cook University in north Queensland said it was the fourth time the Great Barrier Reef had bleached severely.

The survey estimated that a 1 degree Celsius rise in temperatures had caused four bleaching events in the past 19 years.

"It is fair to say that this is extremely concerning for the long-term health of the reef," he said.

"It is facing a number of stresses, but I think the outside stress is coral bleaching, and we have now seen two major events in two years, which we have never seen before - that is unprecedented.

"In 1998, 2002, 2016, and now in 2017 - bleached corals are not necessarily dead corals, but in the severe central region we anticipate high levels of coral loss."

Coupled with the 2017 mass bleaching event, Tropical Cyclone Debbie struck a section of the Great Barrier Reef in March.

Scientists said the intense, slow-moving system was likely to have caused varying levels of damage along a path up to 100 kilometres in width.

Researchers said any cooling effects related to the cyclone were likely to be negligible in relation to the damage it caused, which unfortunately struck a section of the reef that had largely escaped the worst of the bleaching.

Sorry, this video has expired Video: Footage shows areas of the Great Barrier Reef in the Whitsundays devastated by Cyclone Debbie (ABC News)

Search for unspoiled reefs

Mark Read, the Great Barrier Reef Marine Park Authority's manager of species conservation, said it the authority was working with tourism operators to find reefs that had not been affected by bleaching.

"To see whether or not there are areas we need to put additional resources towards protecting," he said.

"Sure there's some areas that have been hit incredibly hard by the bleaching and the cyclone, but it's still a magnificently large place with some areas that have been largely unaffected and that are still in very good condition."

Topics: great-barrier-reef, oceans-and-reefs, climate-change, environment, science-and-technology, academic-research, earth-sciences, townsville-4810, james-cook-university-townsville-4811, qld, australia, cairns-4870, mackay-4740

First posted</s>Two-thirds of Australia's Great Barrier reef has been devastated by back-to-back years of "severe" coral bleaching, aerial surveys have found, raising fears that the natural wonder may not fully recover.

While mass bleaching has been recorded on the Great Barrier Reef before, researchers say two events have never occurred in such close proximity.

Coral bleaching occurs when abnormal environmental conditions — such as heightened sea temperatures — push corals to expel tiny photosynthetic algae causing them to turn white.

The damage was recorded by the Australian Research Council's Centre of Excellence for Coral Reef Studies, which carried out separate studies over the past two years.

Its 2016 survey found the top third of the reef had experienced the most intense bleaching. But research completed last week recorded more damage along the 1,400 mile long reef's middle third.

"The combined impact of this back-to-back bleaching stretches for [900 miles], leaving only the southern third unscathed," ARC director Terry Hughes said Monday.

He said bleaching can be caused by weather patterns such as El Nino as well as higher temperatures driven by global warming.

While the 2016 bleaching was part of a "global event associated with the 2015-2016 El Nino," this year has more to do with a "very mild winter and [summer] heatwaves" on the east coast of Australia, Hughes said.

Situated on Australia's north east coast, the Great Barrier Reef was given World Heritage status in 1981.

It is described by the Australian government as one of the world's natural wonders.

Severe bleaching events have been recorded previously on the Great Barrier Reef in 1998 and 2002.

Bleached corals can recover if the temperature drops and algae can recolonize. But experts warn this process can take up to 10 years.

James Kerry, who was part of the aerial survey team, said: "It takes at least a decade for a full recovery of even the fastest growing corals, so mass bleaching events 12 months apart offers zero prospect of recovery for reefs that were damaged in 2016."

The researchers also said a section of the reef untouched by the bleaching was damaged by Tropical Cyclone Debbie last month.

But while Hughes said the reef was likely struggling with multiple problems, the most pressing was global warming.

"As temperatures continue to rise the corals will experience more and more of these events. One degree Celsius of warming so far has already caused four events in the past 19 years," Hughes said. "Ultimately, we need to cut carbon emissions, and the window to do so is rapidly closing."

Jon Brodie, a water quality expert who was not involved in the research, told the Guardian he believes the reef is now in a "terminal stage."

"Last year was bad enough, this year is a disaster year," he told the newspaper.</s>Sign up for one of our email newsletters.

Scientists just back from a 5,000 mile aircraft survey of Australia's Great Barrier Reef pronounced a dire verdict Sunday: Warm waters have severely bleached large swaths of its corals for the second year in a row in a deadly one-two punch.

In 2016, two thirds of corals in the northern sector of the reef died after severe bleaching from unusually warm waters. Now this year, researchers with the ARC Centre of Excellence for Coral Reef Studies at James Cook University in Queensland, who reported the previous findings, say that the reef's central sector has been hit by another year of damaging warmth.

“We've had a back-to-back bleaching for the first time,” said Terry Hughes, who directs the center. “So we redid our aerial surveys again, which was a bit tough. I was hoping to never have to do it again.”

After that first survey, Hughes tweeted: “I showed the results of aerial surveys of #bleaching on the #GreatBarrierReef to my students, And then we wept.”

Coral bleaching occurs when unusually warm waters provide a stress to corals that in turn trigger a mass exodus of photosynthetic algae, called zooxanthellae, from their cells. The corals lose color and turn white, an outward indicator that their metabolism has been upended. The stronger the bleaching and the longer it goes on, the more likely corals are to die.

The Great Barrier Reef, the largest structure of its kind, is about 1,400 miles long. Nine hundred miles of that length have now experienced severe bleaching at some point during the past two years.

This year has seen the major bleaching shift southward, toward reefs just offshore of major population centers such as Cairns and Townsville.

The current survey encompassed 800 individual coral reefs — including many surveyed last year.

“Last year we lost 67 percent on average of the corals in the northern 430 miles of the barrier reef, between March and October,” Hughes said. “We're likely to see something similar happen now in the middle third this year.”

“That's obviously an enormous loss over two-thirds of the Great Barrier Reef,” he added. “I 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.”

Temperatures in the waters surrounding the reef were so abnormally high last year that scientists concluded there was little doubt they could be attributed to a changing climate.

There have been four historic bleachings of the Great Barrier Reef in the past two decades as the planet has warmed by about 1.8 degrees, Hughes notes.

The prior large scale bleachings occurred in 1998, a dramatic El Niño year, and 2002. 2016 was another major El Niño year, but 2017 is not. Thus, the reef is now bleaching in both non-El Niño years and in consecutive years.

If major bleachings are becoming more common, that raises questions about the reef's ability to recover from such assaults at a time when global ocean temperatures are expected to continue to rise further.

Typically, corals require 10 years or more to recover from bleaching. Some species require considerably longer than that.

Scientists fear the planet will easily coast past 1.5 degrees Celsius in coming decades — and 2 degrees of warming will also be very difficult to prevent with the current warming trajectory.

A 2016 scientific study found that most of the world's corals will be threatened with “severe degradation” under either of these two warming scenarios. But limiting the Earth's warming to 1.5 degrees by the end of the century might allow at least some corals to adapt to the new climate.</s>Two-thirds of the Great Barrier Reef has now been devastated by severe coral bleaching, with damage occurring further south this year, Queensland scientists say.

Two of the world's leading experts on coral bleaching in the Great Barrier Reef said aerial surveys they conducted this year along the reef's entire length showed an accelerated rate of bleaching in the central section.

The ARC Centre of Excellence for Coral Reef Studies undertook the aerial surveys in both 2016 and 2017.

In 2016, bleaching was most severe in the northern third of the Reef, while one year on the middle third has experienced the most intense coral bleaching.

Dr James Kerry from James Cook University in north Queensland, who was one of the scientists involved in the surveys, said the latest damage had occurred in a stretch from Cooktown to Townsville.

"Last year we saw severe bleaching in the northern third, and this year we have seen severe bleaching on the Great Barrier Reef from about Cooktown down to Townsville, so we are calling that the central third," he said.

"So about two-thirds of the reef now in the past 12 months have had a fairly serious bleaching event."

He said there was little doubt that bleaching was being caused by record-breaking temperatures driven by global warming.

"It is fair to say that this is extremely concerning for the long-term health of the reef," he said.

"It is facing a number of stresses, but I think the outside stress is coral bleaching, and we have now seen two major events in two years, which we have never seen before - that is unprecedented."

He said it was the fourth time the Great Barrier Reef had bleached severely.

"In 1998, 2002, 2016, and now in 2017 - bleached corals are not necessarily dead corals, but in the severe central region we anticipate high levels of coral loss," he said.

Coupled with the 2017 mass bleaching event, Tropical Cyclone Debbie struck a section of the Great Barrier Reef in March.

Scientists said the intense, slow-moving system was likely to have caused varying levels of damage along a path up to 100 kilometres in width.

Researchers said any cooling effects related to the cyclone were likely to be negligible in relation to the damage it caused, which unfortunately struck a section of the reef that had largely escaped the worst of the bleaching.</s>The Great Barrier Reef is dying, and there might be zero hope of recovery.

Australia’s Great Barrier Reef is approaching “terminal stage” after two years of consecutive mass coral bleaching, according to scientists who just got back from an aerial survey of the World Heritage site, as reported by Express UK.

Researchers, who recently surveyed the 2,250 km long Great Barrier Reef, said that unusually warm waters caused severe coral bleaching on two-thirds of the reef. The bleaching data on the world’s largest reef was collated after researchers surveyed about 800 individual coral reefs.

A previous survey conducted last year confirmed that two-thirds of corals in the northern section of the Great Barrier Reef are dying due to warm waters caused by global warming.

This year, researchers from ARC Center of Excellence for Coral Reef Studies at James Cook University in Queensland announced that the central part of the reef has been severely damaged following another year of warm climate.

“We’ve had a back-to-back bleaching for the first time,” said Professor Terry Hughes, who directs the center.

“So we redid our aerial surveys again, which was a bit tough. I was hoping to never have to do it again,” Hughes tweeted. “I showed the results of aerial surveys of #bleaching on the #GreatBarrierReef to my students, And then we wept.”

Coral mass bleaching happens when warmer-than-usual waters cause the coral to expel living algae, changing its color to white. Coral bleaching, usually, is no cause for worry since mildly bleached coral can recover itself once temperature drops. Global warming, however, has been keeping the waters warm longer than usual, thus not giving the Great Barrier Reef enough time to recover itself.

“Bleached corals are not necessarily dead corals, but in the severe central region we anticipate high levels of coral loss,” James Kerry, senior research officer at the ARC Center of Excellence for Coral Reef Studies, explains.

This is the fourth time the Great Barrier Reef has suffered mass coral bleaching since 1998.

As previously reported by The Sun, category four Cyclone Debbie, which left a trail of disaster in northeast Australia and New Zealand, could have damaged the Great Barrier Ref even more. The amount of damage the storm left in its wake is still unknown at this point, but scientists said it could range from minor to severe.

Queensland Parks and Wildlife Service and the Great Barrier Reef Marine Park Authority conducted a study last week to determine the extent of the damage and have found destroyed coral at famous snorkeling spots.

“The feedback that’s coming back is the more sheltered areas have come out a bit better, but they all seem to have suffered some form of damage,” Association of Marine Park Tourism Operators’ Brendon Robinson said.

Professor Hughes said that the Great Barrier Reef is not considered dead yet, but it’s going there if no concrete action plan is made to salvage the site.

“Clearly the reef is struggling with multiple impacts. Without a doubt the most pressing of these is global warming,” he said.

Hughes reminded Australia to take decisive action in saving the reef since tourists are spending £3.15 billion each year to pay the tourist attraction a visit.</s>Over 900 miles of Australia’s Great Barrier Reef has been damaged by coral bleaching.

The bleaching - or loss of algae - affects two-thirds of the reef.

The latest damage is concentrated in the middle section, last year’s bleaching hit mainly the north.

Experts fear the proximity of the two events will give damaged coral little chance to recover.

Warmer oceans are said to be to blame.

Prof Terry Hughes, from James Cook University , said: “Since 1998, we have seen four of these events and the gap between them has varied substantially, but this is the shortest gap we have seen.

“The sooner we take action on global greenhouse gas emissions and transition away from fossil fuels to renewables, the better.”

Almost 800 coral reefs across 5,000 miles were assessed by the Australian Research Council’s Centre of Excellence for Coral Reef Studies.

The findings showed only the southern section of the reef remain relatively unscathed.

Researcher Dr James Kerry said the damage was unprecedented.

“The central third this year, I would say, was as severe in terms of bleaching as what we saw as the northern third last year,.

“For those reefs that were hit two years in a row, it is effectively a double whammy. They have had no chance to recover from last year’s events.

“Ultimately, we need to cut carbon emissions, and the window to do so is rapidly closing.

“It takes at least a decade for a full recovery of even the fastest growing corals, so mass bleaching events 12 months apart offers zero prospect of recovery for reefs that were damaged in 2016.”

Coral bleaching is caused by rising water temperatures resulting from two natural warm currents.

It is made worse by man-made climate change, as the oceans have to absorb about 93% of the increase in the Earth’s heat.

Coral reefs could be saved by 3D printing as climate change continues to decimate underwater ecosystems

Bleaching happens when corals under stress drive out the algae known as zooxanthellae that give them colour.

If normal conditions return, the corals can recover, but it can take decades, and if the stress continues the corals can die.

The latest damage happened without the assistance of El Niño, a weather pattern previously associated with bleaching events.

The reef - a vast collection of thousands of smaller coral reefs stretching from the northern tip of Queensland to the state’s southern city of Bundaberg - was given World Heritage status in 1981.

The UN says it is the “most biodiverse” of all the World Heritage sites, and of “enormous scientific and intrinsic importance”.

Tropical Cyclone Debbie also hit the reef last month, damaging a 70 mile wide area-wide that had been largely undamaged until that time.</s>Scientists in Australia have recorded "severe" coral bleaching across large parts of the Great Barrier Reef for the second time in 12 months.

In a news release on Monday, James Cook University (JCU) in Australia said that aerial surveys had shown that the middle third of the reef had seen the most intense bleaching, while in 2016 bleaching had hit the northern third the hardest.

"The combined impact of this back-to-back bleaching stretches for 1,500 km (900 miles), leaving only the southern third unscathed," Terry Hughes, director of the Australian Research Council's (ARC) Centre of Excellence for Coral Reef Studies, said in a statement. The Centre is headquartered at JCU.

 

 Hughes, who was involved with the aerial surveys in 2016 and 2017, went on to add that the bleaching had been caused "by record-breaking temperatures driven by global warming. This year, 2017, we are seeing mass bleaching, even without the assistance of El Niño conditions."

Bleaching takes place when "abnormal" conditions – such as increased sea temperatures – result in coral getting rid of very small photosynthetic algae, according to the ARC and JCU.

When this happens, the corals "bleach" and turn white. While they can recover if the sea temperature falls again, they can die if it doesn't.

"This is the fourth time the Great Barrier Reef has bleached severely – in 1998, 2002, 2016, and now in 2017," James Kerry, who was also involved in the aerial surveys, said.

 

 "Bleached corals are not necessarily dead corals, but in the severe central region we anticipate high levels of coral loss," Kerry added. "It takes at least a decade for a full recovery of even the fastest growing corals, so mass bleaching events 12 months apart offers zero prospect of recovery for reefs that were damaged in 2016."

As well as the mass bleaching, a corridor of the Great Barrier Reef had to contend with the impact of Tropical Cyclone Debbie towards the end of March. This, JCU said, "was likely to have caused varying levels of damage along a path up to 100 km in width."

Hughes said that the reef was struggling with multiple impacts. "Without a doubt the most pressing of these is global warming," he added.

 

 "As temperatures continue to rise the corals will experience more and more of these events: 1°C of warming so far has already caused four events in the past 19 years."</s>Severe coral bleaching has ravaged two-thirds of the Great Barrier Reef off Australia's northeastern coast, marking the fourth massive bleaching event in the past 19 years, according to the results of an aerial survey.

The world's largest coral reef system has experienced massive bleaching for the second year in a row. That makes this the first time the reef has not had several years to recover between bleaching events, according to researchers. The ARC Center of Excellence for Coral Reef Studies released results of an expansive aerial survey of the reef Sunday.

“The combined impact of this back-to-back bleaching stretches for 900 miles, leaving only the southern third unscathed,” according to Prof. Terry Hughes, Director of the ARC Centre of Excellence for Coral Reef Studies.

While the 2016 bleaching event was in part due to El Niño conditions, this year's bleaching is due to record-breaking temperatures driven by global warming, according to Hughes, who undertook the aerial surveys in both 2016 and 2017.

The vibrant colors that draw thousands of tourists to the Great Barrier Reef each year come from algae that live in the coral's tissue. When water temperatures become too high, coral becomes stressed and expels the algae, which leave the coral a bleached white color. While some areas are expected to regain their normal color as temperatures drop, other parts of the reef have already experienced significant mortality of bleached coral.

Massive coral bleaching events have occurred 1998, 2002, 2016 and 2017, according to Dr. James Kerry.

Bleached coral doesn't mean the coral is dead, Kerry noted, but the chances of recover are dramatically reduced when the coral is given little time to recover.

“It takes at least a decade for a full recovery of even the fastest growing corals, so mass bleaching events 12 months apart offers zero prospect of recovery for reefs that were damaged in 2016," Kerry said in a statement.</s>Back-to-back bleaching is killing huge tracts of the Great Barrier Reef, with almost none of the coral affected in 2016 expected to recover.

Recent aerial surveys by the Australian Research Council's Centre of Excellence for Coral Reef Studies have revealed only the southern third of the reef is unscathed from the bleaching events.

Researcher Terry Hughes said mass bleaching happened in 2017 even without the assistance of El Nino, which normally brings warmer sea surface temperatures.

'The bleaching is caused by record-breaking temperatures driven by global warming,' Professor Hughes said.

'Ultimately, we need to cut carbon emissions, and the window to do so is rapidly closing.'

Warmer water temperatures cause coral to expel their algae, turning them bright fluorescent colours and eventually bone white.

Marine biologist James Kerry said bleached corals were not necessarily dead but it was anticipated high levels of coral would be lost in the central region of the reef, which experienced the most intense bleaching this year.

'It takes at least a decade for a full recovery of even the fastest growing corals, so mass bleaching events 12 months apart offers zero prospect of recovery for reefs that were damaged in 2016,' Dr Kelly said.

Tropical Cyclone Debbie also destroyed parts of the reef around the Whitsundays, a popular tourist destination that had largely escaped the worst of the bleaching so far.

While cyclones normally cause the water temperature to drop, Prof Hughes said any cooling effects were likely to be negligible in relation to the damage caused by the slow-moving Category 4 system.

'Clearly the reef is struggling with multiple impacts,' he said.

The Great Barrier Reef is known to have experienced four bleaching events in 1998, 2002, 2016 and 2017.</s>An unprecedented amount of coral bleaching for two consecutive years has severely damaged two-thirds of Australia’s Great Barrier Reef, aerial surveys have shown.

Scientists at the ARC Centre of Excellence for Coral Reef Studies recorded severe coral bleaching for the second time in 12 months after surveying the Great Barrier Reef’s entire 2,300km-long (1,500) miles ecosystem.

“This is the fourth time the Great Barrier Reef has bleached severely – in 1998, 2002, 2016, and now in 2017. Bleached corals are not necessarily dead corals, but in the severe central region we anticipate high levels of coral loss,” said Dr. James Kerry of James Cook University. 



“It takes at least a decade for a full recovery of even the fastest growing corals, so mass bleaching events 12 months apart offers zero prospect of recovery for reefs that were damaged in 2016.”

READ MORE: Australia’s Great Barrier Reef on brink of collapse - scientists

The study found that while the northern third of the reef experienced the most severe bleaching last year, the middle third experienced the most intense coral bleaching this year, resulting in catastrophic damage of the natural wonder of the world.

“The combined impact of this back-to-back bleaching stretches for 1,500km (900 miles), leaving only the southern third unscathed,” said Prof. Terry Hughes who undertook the aerial surveys in both 2016 and 2017.

“The bleaching is caused by record-breaking temperatures, driven by global warming. This year, 2017, we are seeing mass bleaching, even without the assistance of El Niño conditions.”

The 2017 survey of the reef covered more than 8,000km (5,000 miles) and nearly 800 coral reefs that matched the 2016 aerial surveys. Last year, Climate Central found bleaching has hit 93 percent of the reef, with 80 percent enduring severe bleaching.

READ MORE: Viral spiral: 'Obituary' for embattled Great Barrier Reef slammed for hyperbole

The mass bleaching, coupled with the destructive Tropical Cyclone Debbie in March, has struck a previously undamaged section of the reef.

“Clearly the reef is struggling with multiple impacts,” explains Prof. Hughes. “Without a doubt the most pressing of these is global warming. As temperatures continue to rise the corals will experience more and more of these events: 1°C of warming so far has already caused four events in the past 19 years.”

“Ultimately, we need to cut carbon emissions, and the window to do so is rapidly closing.”
The Australian Research Council reports that two thirds of the Great Barrier Reef have suffered from severe coral bleaching, denoting a second consecutive year of severe bleaching.