It is the third massive bleaching that the Great Barrier Reef has undergone in five years, further weakening its precious ecosystem. It is not only due to global warming and anthropogenic activities. The Australian government seems to favor economic interests at the expense of this unique biodiversity.
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The Great Barrier Reef experienced a third severe episode of coral bleaching in five years in the southern summer, a phenomenon caused by global warming and who threatens this ecosystem unique Australian. Listed as World Heritage by UNESCO in 1981, the Great Barrier Reef extended over approximately 2,300 kilometers along the northeast coast of Australia and was the largest coral reef on the planet.
The north of this ecosystem had already undergone two unprecedented episodes of coral bleaching in 2016 and 2017 and Australia again reviewed the outlook for this complex last summer, now considering them as “very bad”.
However, the Great Barrier Reef has suffered in recent months from “very extensive” damage, especially in previously spared areas which have become the scene of a “moderate or severe bleaching” of corals, announced on Thursday the Authority of the Great Marine Park Barrier Coral, who realizes a study of the area by aerial reconnaissance. The damage was less significant in the tourist areas near Cairns, in the State of Queensland, and in the Whitsunday Islands, according to the Authority.
The discoloration reflects a decline
Whitening is a wasting phenomenon which results in discoloration. It is due to the rise in water temperature, which leads to the expulsion of algae symbiotics that give coral its color and his nutrients. Reefs can recover if the water cools, but they can also die if the phenomenon persists.
The Great Barrier Reef is also threatened bypurple acanthaster, a star sea devouring corals, which has proliferated due to pollution and agricultural runoff.
Scott Morrison’s Conservative government accused of dragging feet in fight against global warming so as not to sacrifice the lucrative coal industry which employs many Australians.
The study made public by the Authority ” shows the urgent need to conduct climate policies to preserve reefs “Said Shani Tager of the Australian Society for the marine preservation.
Below is a tweet from Terry Hughes, professor and director of the ARC Center of Excellence for Coral Reef Studies at James Cook University, showing bleaching south of the coast.
Weekly reef health update as of March 26, 2020. © Great Barrier Reef Marine Park. To obtain a fairly faithful translation into French, click on the cog wheel at the bottom right, then on subtitles, then on automatically generated English, then Translate automatically, then on Choose “French”.
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The Great Barrier Reef is getting worse
Article by Julie Kern, published on December 4, 2019
It is not a surprise, the Great Barrier Reef located off Australia suffers particularly from global warming. So much so that the latest report from the Australian government is very pessimistic about its future. Threatened by Man and the consequences of these upheavals, Australia offers an action plan to save this unique ecosystem.
Despite the financial and political efforts put in place by the Australian government, the Great Barrier Reef has suffered terribly in recent years. In 2016 and 2017, an unprecedented whitening phenomenon affected almost the whole of this exceptional ecosystem.
According to Australian government report On the future of the Great Barrier Reef of 2019, global warming is the first threat to coral reefs, in Australia and around the world. The prospects for the one who is considered one of the wonders of the world are bleak. Experts in the report say they have gone from “bad” to “very bad”.
Coral reefs threatened by climate change and Man
2016 and 2017 were two tragic years for the Great Barrier Reef. Six cyclones have caused floods on the continent. Unhealthy waters have altered the fragile balance in which we live coral reefs. In addition, a species particularly voracious starfish, called “crown of thorns”, feeding coral invaded the Australian coast.
Other threats, this time directly linked to human activity, were identified by the experts behind the report. They are particularly concerned by the contamination flowing rivers in fine in the ocean, but also by the urban development of the coasts and the peach illegal in the Great Barrier Reef area.
Steps to reverse the trend
To contain the bleaching of corals and, ultimately, their outright disappearance, Australia plans several measures. The first is to improve the quality of the water in which the corals live. For this, the country has released $ 600 million and is working with farmers. The aim is to reduce the runoff of polluted river waters to the sea, but also to limit the erosion of land in the basins coastal. The water quality will be checked annually to determine the effectiveness of the measures.
The government is also betting on scientific research. A first envelope of $ 6 million was released so that the Reef Restoration and Adaptation Program can study the resilience corals, i.e. their ability to overcome and adapt to drastic changes in their environment.
And finally, Australia, signatory to the Paris Agreements, hopes to reduce its broadcasts of greenhouse gas from 26 to 28% (compared to 2005) by 2030. Despite all these initiatives, it will not be able to act alone in the face of rising ocean temperatures which threatens an ecosystem already out of breath.
The Great Barrier Reef is going badly and will not recover from warming waters
Article published on March 10, 2017 by Xavier Demeersman
Another bad news regarding the Great Barrier Reef, located off northeast Australia: in 2017, bleaching intensified in its central part. More than 1,500 km are now affected. Above all, scientists warn, the phenomenon occurred two years in a row, which did not give the corals time to recover.
It’s been two consecutive years that the Great Barrier Reef, world treasure of biodiversity registered since 1981 in the heritage of humanity, is victim of severe bleaching. Experts are very worried about her because, according to them, the chances that the most affected parties can recover are very low. Indeed, it takes about ten years for fast growing specimens to recover. As James Kerry, a biologist at James Cook University (Australia) points out, “Two serious bleaching episodes twelve months apart mean that the reefs damaged in 2016 have no chance of recovering”.
Whitening is caused by the departure of an alga with which the organism lives in symbiosis – it owes in particular its color and a large part of its food. It’s the stress created by the warming of the waters which is the cause of bleaching. The researchers recall that this is the fourth time in modern history that this phenomenon has occurred: it first took place in 1998, then in 2002 and, back to back, in 2016 and 2017.
When a coral expels the algae with which it lived in symbiosis. © Brett Lewis, Queensland University of Technology, Youtube
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Whitening of the Great Barrier extends south
During their recent flyovers of Coral reefs, James Kerry and his colleagues noted that bleaching had increased in the central part of this living structure – the largest on Earth, 2,300 km long. After having mainly affected the north in 2016, the phenomenon has extended this year to the south. Now, a portion of some 1,500 km is affected.
For the moment, only the southern parts remain relatively spared: around 10% of corals there suffer from bleaching against more than 60% in the north and center. However, researchers fear that the recent category 4 cyclone Debbie, in March, may have caused significant damage in this area, without having cooled the waters enough to reverse the trend.
Pessimists, scientists fromAustralian Research Council’s Center of Excellence for Coral Reef Studies urge the Australian government to take the necessary measures to reduce global warming and preserve this vital ecosystem.
In 2016, the bleaching of the Great Barrier Reef mainly affected the oldest part, to the north
Article by Xavier Demeersman published on 29/11/2016
It is the third large-scale bleaching event that has affected the Great Barrier Reef since the end of the XXe century. The one in 2016, still caused by the rise in water temperature, is the most devastating of all, causing the death of two-thirds of the oldest part, north of the reef. All of this is happening with less than one degree of global warming.
2016, which already promises to be the warmest year for the WMO since the first temperature readings in 1890 (it would be the third consecutive record year) will be remembered as a dark year for the Great Barrier Reef.
The first, the global warming responsible for the global rise in temperaturesair but also that of the surface of the oceans, is the main cause of the bleaching of great coral reefs which extend shallowly along the coasts of north-eastern Australia for about 2,300 km. Recall that the warming of the water causes the coral to expel symbiotic algae which give them their color and their nutrients.
This year, in the past nine months, 67% of the oldest and most preserved corals of the great reef listed as World Heritage by Unesco, mainly located in a strip of 700 km in the northern part – an area until there relatively spared -, died due to a rise of two degrees above the normal maximum of the water temperature.
Increasingly serious events
“We saw three bleaching events[19982002andthisone[19982002etcelui-ciEditor’s note ; see also the initial article below]and, each time, it can be explained by the warming of the waters ” told report author Terry Hughes, director of the CRA, to CNN (Center of Excellent for Coral Reef Studies) who, by means of aerial reconnaissance, could see the extent of the damage.
“It gives food for thought, he added, because each of these three events was more serious than the previous one and it happened with less than one degree of global warming “. However, the path we are taking on a global scale leads rather to two degrees of warming. According to the authors of the report, it will take between 10 and 15 years for the affected reefs to recover … provided of course that there are no further increases in temperature.
If nothing is done by December 1 to further protect it, the Great Barrier Reef will be on the list of sites in danger, warned Unesco (which almost happened in 2015). “This is the devastating price we pay when the Australian government supports the coal industry at arm’s length, deplored Shani Tager of Greenpeace Australia, quoted by AFP. A credible plan to protect the reef must begin with global warming and the ban on new mines. “
There is still good news: the reefs in the south were much less affected, only 1% of the corals died in the south. They are 6% in the center (see map).
Stressed corals
Initial article by Marie-Céline Jacquier published on 03/04/2016
Scientists pull the doorbell alarm after analyzing aerial images of the Great Barrier Reef in Australia: large areas are currently experiencing the worst bleaching episode ever recorded.
The Great Barrier Reef, located northeast of the Australian coast, is home to 400 species of coral and 1,500 species of Pisces. It is inscribed on the World Heritage List ofUnesco. Bleaching takes place when the corals are stressed by hot ocean temperatures; they then reject the symbiotic alga which provides them withenergy by photosynthesis. Without these algae, corals turn white and risk dying.
Australian scientists conducted an aerial survey of 520 reefs north of Cairns, Australia, on the northernmost part of reef : “We see very severe bleaching in the northern part of the reef”said Professor Terry Hughes of James Cook University. “We found only four out of 520 reefs that were not bleached to some extent and more than 95% of the reefs were in the two most severe bleaching categories. “ Previously, a bleaching event dating from 2002 had led to 18% of the reefs classified in these two categories.
In one communicated, he even says: “It was the saddest research trip of my life, adding that the gravity is much larger than in previous bleaching episodes in 2002 or 1998 ”.
The warming and acidification of the waters are in question
The event of bleaching The current one started in June 2014, when it appeared in the central and eastern Pacific. It continued in different places in 2015 and then this year. According to Mark Eakin, a coral expert, by the end of 2015, almost a third of the world’s corals had experienced temperatures high enough to cause bleaching.
Scientists have observed three global bleaching events in 1998, 2010 and today. However, previously, as in 1998, laundering events generally lasted only one year. Each time, they were linked to El Niño. Thus, the current bleaching would be linked to the El Niño 2015-2016 episode, but it started even before El Niño was declared.
Previously, the 1998 episode was the most serious so far and had caused the loss of 16% of coral reefs, according to Mark Eakin. The impact of the current event is unknown. The cause is to be found on the side of global warming which represents a major threat to corals: it increases water temperatures and the pH of the ocean becomes more acid, because of the increase in carbon absorbed by the sea.ocean acidification may interfere with the growth of corals.
A 2007 study published in Science had already alerted on the impact of global warming on corals: between 2050 and 2100, the atmospheric CO concentration2 should exceed 500 ppm and temperatures rise by 2 ° C, values that exceed those of the last 420,000 years. This article provided that in the XXIe century global warming and the acidification ofocean compromise carbon build-up and corals are becoming increasingly scarce.
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