Archives par mot-clé : Corals

Record Coral Cover Of Great Barrier Reef Shames Climate Alarmists, Media

by P. Ridd, July 23, 2021 in WUWT


The annual data on coral cover for the Great Barrier Reef, produced by the Australian Institute of Marine Science, was released on Monday showing the amount of coral on the reef is at record high levels.

Record high, despite all the doom stories by our reef science and management institutions.

Like all other data on the reef, this shows it is in robust health. For example, coral growth rates have, if anything, increased over the past 100 years, and measurements of farm pesticides reaching the reef show levels so low that they cannot be detected with the most ultra-sensitive equipment.

This data is good news. It could hardly be better. But somehow, our science organizations have convinced the world that the reef is on its last legs. How has this happened?

Fishy Business: Alleged Fraud over Ocean Acidification Research, Reversal on Coral Extinction

by R. Alexander, June 28, 2021 in ScienceUnderAttack


In the news recently have been two revelations about the sometimes controversial world of coral reef research. The first is fraud allegations against research claiming that ocean acidification from global warming impairs the behavior of coral reef fish. The second is an about-face on inflated estimates for the extinction risk of Pacific Ocean coral species due to climate change.

The alleged fraud involves 22 research papers authored by Philip Munday, a marine ecologist at JCU (James Cook University) in Townsville, Australia and Danielle Dixson, a U.S. biologist who completed her PhD under Munday’s supervision in 2012. The fraud charges were made in August 2020 by three of an international group of mostly biological and environmental scientists, plus the group leader, fish physiologist Timothy Clark of Deakin University in Geelong, Australia. The Clark group says it will publicize the alleged data problems shortly.

The research in question studied the behavior of coral reef fish in slightly acidified seawater, in order to simulate the effect of ocean acidification caused by the absorption of up to 30% of humanity’s CO2 emissions. The additional CO2 has so far lowered the average pH – a measure of acidity – of ocean surface water from about 8.2 to 8.1 since industrialization began in the 18th century.

Munday and Dixson claim that the extra CO2 causes reef fish to be attracted by chemical cues from predators, instead of avoiding them; to become hyperactive and disoriented; and to suffer loss of vision and hearing. But Clark and his fellow scientists, in their own paper published in January 2020, debunk all of these conclusions. Most damningly of all, the researchers find that the reported effects of ocean acidification on the behavior of coral reef fish are not reproducible – the basis for their fraud allegations against the JCU work.

Peter Ridd: It’s the science that’s rotten, not the Great Barrier Reef

by P. Homewood, Dec 7, 2020 in NotaLotofPeopleKnowThat


 

The International Union for Conservation of Nature has released its latest report on the state of the Great Barrier Reef. It has turned up the volume by one notch, claiming the threat to the reef has gone from “significant concern” to “critical”. It blames climate change, agricultural pollution, coastal development, industry, mining, shipping, overfishing, disease, problematic native species, coal dust — you name it, it is killing the reef.

But the report is just a rehash of old, mostly wrong or misleading information produced by generally untrustworthy scientific institutions with an activist agenda and no commitment to quality assurance.

It is remarkable that the world has been convinced that one of its most pristine ecosystems is on its last legs. Part of the problem is that, being underwater and a long way from the coast, very few people visit the reef. The truth is hidden. Those of us in North Queensland living adjacent to the reef, and tourists from elsewhere, can report the water is iridescent clear blue and totally unpolluted. The fish and coral are fabulous.

Measuring Old Corals & Coral Reefs (Part 1)

by J. Marohasy, Nov 29, 2020 in WUWT


Fundamental to science is measurement. It is a way of objectively assessing something, anything, even the state of a coral reef, even of an individual coral. Historically coral growth rates were measured by coring the really old massive Porites.

Like tree rings in temperate forests, the massive old Porites can be cored to see the banding and from this it is possible to calculate coral calcification rates which are a measure of the growth rate of individual corals.

Peter Ridd has been asking for some quality assurance of so many of the measurements relating to Great Barrier Reef health, including coral growth rates. Key Australian institutions have responded by stonewalling, and in the case of James Cook University, actually sacking him. After two rounds in the federal courts his appeal against his dismissal is finally going to the High Court of Australia, with the next hearing probably in February 2021. While the lawyers are preoccupied with Peter’s rights, or otherwise, to academic freedom and freedom of speech, my concern is whether Peter is actually telling the truth when he says that the Great Barrier Reef is resilient and definitely not dying from coral bleaching, though there is a problem with the integrity of the science.

 

Half the Reef destroyed but they won’t release the data

by JoNova, Oct 16, 2020


The future of the entire 350,000 km2 Great Barrier Reef hangs in the balance — as the coralapocalypse has wiped out 50% of the coral in just 25 years. Lordy! If only we’d built some off-shore wind farms on the reef to protect it! We could cover whole islands with solar panels? What are we thinking!

But as Peter Ridd points out, AIMS (The Australian Institute of Marine Science) surveys around 100 reefs every year — and for the last 35 years — and they find things are roughly the same. See the graph below.

Somehow Terry Hughes — and the Centre of Excellence for Integrated Coral Reef Studies — gets up to $4 million each year to report on the reef but won’t release the data behind the mass media campaign.

The ABC — which gets nearly $3 million dollars every single day — can’t even pick up the phone to interview AIMS or Peter Ridd and ask one hard question of Terry Hughes’ “Excellent” centre. (We all know why they had to put the word “excellence” in the title, it was the only way the word would ever be used to describe an activist group pretending to be scientists.)

And we all know that if anyone at James Cook University (JCU) has any doubts about the quality of the output from the “Excellent” centre they won’t be saying a word or they’ll get sacked like Peter Ridd did.

JCU — still supporting junk science and ignoring that other case of potential fraud?

Claim: Ocean acidification causing coral ‘osteoporosis’ on iconic reefs

by WOODS HOLE OCEANOGRAPHIC INSTITUTION, August, 28, 2020 in WUWT


Scientists have long suspected that ocean acidification is affecting corals’ ability to build their skeletons, but it has been challenging to isolate its effect from that of simultaneous warming ocean temperatures, which also influence coral growth. New research from the Woods Hole Oceanographic Institution (WHOI) reveals the distinct impact that ocean acidification is having on coral growth on some of the world’s iconic reefs.

 

IMAGE: WHOI SCIENTIST ANNE COHEN (LEFT) AND MIT-WHOI JOINT PROGRAM STUDENT NATHAN MOLLICA EXTRACT CORE SAMPLES FROM A GIANT PORITES CORAL IN RISONG BAY, PALAU. view more CREDIT: PHOTO BY RICHARD BROOKS, LIGHTNING STRIKE MEDIA PRODUCTIONS, PALAU.

In a paper published Aug. 27, 2020, in the journal Geophysical Research Letters, researchers show a significant reduction in the density of coral skeleton along much of the Great Barrier Reef–the world’s largest coral reef system–and also on two reefs in the South China Sea, which they attribute largely to the increasing acidity of the waters surrounding these reefs since 1950.

“This is the first unambiguous detection and attribution of ocean acidification’s impact on coral growth,” says lead author and WHOI scientist Weifu Guo. “Our study presents strong evidence that 20th century ocean acidification, exacerbated by reef biogeochemical processes, had measurable effects on the growth of a keystone reef-building coral species across the Great Barrier Reef and in the South China Sea. These effects will likely accelerate as ocean acidification progresses over the next several decades.”

Roughly a third of global carbon dioxide emissions are absorbed by the ocean, causing an average 0.1 unit decline in seawater pH since the pre-industrial era. This phenomenon, known as ocean acidification, has led to a 20 percent decrease in the concentration of carbonate ions in seawater. Animals that rely on calcium carbonate to create their skeletons, such as corals, are at risk as ocean pH continues to decline. Ocean acidification targets the density of the skeleton, silently whittling away at the coral’s strength, much like osteoporosis weakens bones in humans.

Reefs’ Neon Colors A Defense Against Coral Bleaching

by B. Bruno,  May 22, 2020 in ClimateChangeDispatch


Some coral reefs are adapting to warming ocean temperatures by making their own sunscreen in the form of bright neon colors — a strategy that invites coral animals to return to reefs and is seen as a critical adaptation to maintain healthy coral reefs around the world.

In a study published Thursday in the journal Current Biology, researchers at the University of Southampton detail a series of controlled laboratory experiments they conducted at their coral aquarium facility.

In the experiments, “colorful” coral bleaching events cause coral to produce a layer of vibrant sunscreen which encourages the coral animals vital to a mutually beneficial “symbiosis” relationship to return to coral habitats they abandon due to the effects of warming oceans.

The colorful adaptation could prove vital for overcoming the fatal coral bleaching incidents that have threatened coral reefs worldwide.

But the colorful coral bleaching – rather than the white skeleton exposure of common coral bleaching events – is believed to take place due to mild ocean warming or disturbances in their nutrient environment, rather than extreme events.

Colorful bleaching occurred between this past March and April in some areas of the Great Barrier Reef, suggesting some patches of the world’s largest reef system may have better recovery prospects than others.

Coral Catastrophes Imagined

by Jennifer, April 10, 2020 in WUWT


From Jennifer Marohasy’s Blog

April 10, 2020 By jennifer

Exactly one year ago yesterday, I was getting off a train in Proserpine, looking to pickup a hire car to drive to Bowen. I wanted to know if the coral there was all dead, or not. Bowen is a coastal town in North Queensland, not far from Abbott Point that is the coal terminal for the controversial Adani coal mine.

Judge Salvador Vasta had earlier that week handed down his findings regarding the sacking of Peter Ridd. He had exonerated Ridd and explained that James Cook University had wrongly sacked him.

Some claim that it all came to a sorry end for Ridd because he dared to question the consensus of scientific opinion concerning the health of the Great Barrier Reef – particularly the impact of global warming. The university claimed it was because he had become ‘un-collegial’ and did not follow various directives while disclosing confidential information.

These issues were argued in the Federal Circuit Court in Brisbane a month earlier, in March 2019. Very few people realized that at the heart of the case were a couple of what might be best described as fake-news photographs promoted by Terry Hughes.

This is the same Terry Hughes who is now claiming that 60%* of the Great Barrier Reef has been bleached, and that this is an extraordinary catastrophe for which we should all be ashamed.

If Peter Ridd had become un-collegial and disclosed confidential information, it was because he was fed-up with the fake news. As Ridd wrote in chapter 1 of the book that I edited three years ago, a chapter entitled ‘The Extraordinary Resilience of Great Barrier Reef Corals, and Problems with Policy Science’:

New Study: Coral Reefs Thrive Near Acidic Waters (pH ~6.0) Where Seafloor Vents Emit Up To 95,000 ppm CO2

by K. Richard, March 30, 2020 in NoTricksZone


Though it’s believed the 130 ppm increase in atmospheric CO2 concentration since 1750 has caused the ocean waters to “acidify”, on a daily basis 50-380°C metallic acid enriched by CO2 concentrations reaching 60,000 to 95,000 ppm pours through seafloor vents. Nearby coral reefs “thrive” in these high-CO2 conditions.

50 times more CO2 in the oceans than in the atmosphere

Though many believe humans are “acidifying” the oceans by burning fossil fuels and emitting CO2, the ability of humans to impact the oceanic CO2 concentration is already compromised by the observation that the ocean waters contain about 50 times more CO2 (38,000 vs. 750 PgC) than the atmosphere does (North et al., 2014).

Coral tells own tale about El Niño’s past

by Rice University, March 27, 2020 in WUWT


HOUSTON – (March 26, 2020) – There is no longer a need to guess what ocean temperatures were like in the remote tropical Pacific hundreds of years ago. The ancient coral that lived there know all.

A study in Science led by Rice University and Georgia Tech researchers parses the record archived by ancient tropical Pacific coral over the past millennium. That record could help scientists refine their models of how changing conditions in the Pacific, particularly from volcanic eruptions, influence the occurrence of El Niño events, which are major drivers of global climate.

They found the ratio of oxygen isotopes sequestered in coral, an accurate measure of historic ocean temperatures, shows no correlation between estimates of sulfate particles ejected into the atmosphere by tropical volcanic eruptions and El Niño events.

That result could be of particular interest to scientists who suggest seeding the atmosphere with sun-blocking particles may help reverse global warming.

According to Rice climate scientist and primary author Sylvia Dee, previous climate model studies often tie volcanic eruptions, which increase sulfate aerosols in the atmosphere, to increased chances for an El Niño event. But the ability to analyze climate conditions based on oxygen isotopes trapped in fossil corals extends the climatological record in this key region across more than 20 ancient eruptions. Dee said this allows for a more rigorous test of the connection.

“A lot of climate modeling studies show a dynamical connection where volcanic eruptions can initiate El Niño events,” Dee said. “We can run climate models many centuries into the past, simulating volcanic eruptions for the last millennium.

“But the models are just that — models — and the coral record captures reality.”

Coral data that Georgia Tech climate scientist Kim Cobb and her team arduously collected on trips to the Pacific show little connection between known volcanoes and El Niño events over that time. Like tree rings, these paleoclimate archives hold chemical indicators, the oxygen isotopes, of oceanic conditions at the time they formed.

The coral data yields a high-fidelity record with a resolution of less than a month, tracking the El Niño-Southern Oscillation (ENSO) in the heart of the central tropical Pacific.

Climate At A Glance Factchecks–Coral Reefs

by P. Homewood, March 21, 2020 in NotaLotofPeopleKnowThat


Bullet Point Summary:

  • Coral thrive in warm water, not cold water.
  • Recent warming has allowed coral to expand their range poleward, while still thriving near the equator.
  • Coral has existed continuously for the past 40 million years, surviving temperatures and carbon dioxide levels significantly higher than what is occurring today.
  • The primary causes of coral bleaching include oxybenzone (a chemical found in sunscreen), sediment runoff from nearby coastal lands, and cold temperatures like those recorded in 2010 off the Florida coast.
  •  

Short Summary: Coral require warm water, not cold water, to live. Coral cannot live outside of tropical or subtropical waters. (See Figure 1.) As Earth continues to modestly warm, coral are extending their range toward the poles while still thriving at and near the equator. The primary reasons for bleaching events include sediment pollution from nearby coastal lands, chemicals found in sunscreen, and cold temperature events. Coral have existed continuously for the past 40 million years. Coral survived and thrived when temperatures were significantly warmer than they are today.

Figure 1: Coral Reef Locations

Continuer la lecture de Climate At A Glance Factchecks–Coral Reefs

Study: No Evidence Ocean Acidification Harms Coral Reef Fish Behavior

by C. Idso, March10, 2020 in ClimateChangeDispatch


Paper Reviewed: Clark, T.D., Raby, G.D., Roche, D.G., Binning, S.A., Speers-Roesch, B., Jutfelt, F. and Sundin, J. 2020. Ocean acidification does not impair the behavior of coral reef fishes. Nature 577: 370-375.

In an incredibly important and revealing paper published in the journal Nature, Clark et al. (2020) write that “establishing a robust and independently replicated database of the effects of ocean acidification on fishes is essential to gain a reliable understanding of the consequences of climate change on marine ecosystems.”

Such a database, they add, is critical “before drawing broad conclusions and implementing management measures.”

Unfortunately, too many have been far too eager to jump to conclusions when it comes to estimating the impacts of ocean acidification.

And in this regard, Clark et al. note that “a number of highly publicized studies have reported detrimental effects of elevated CO2 levels on the sensory systems and behaviors of fishes, with coral reef fishes appearing to be the most sensitive despite experiencing large daily and seasonal fluctuations in nature (for example, 100-1,300 µatm).”

Such projected detrimental effects include “alterations in olfaction, hearing, vision, learning, behavioral lateralization, activity levels, boldness, anxiety, and susceptibility to predation,” which have led to “dire predictions for fish populations and marine ecosystems.”

But how solid is this body of research?

Clark et al. note there are two important red flags that call the pessimistic ocean acidification projections of fish into question.

IPCC Expert’s 8 Discredited Papers

by Donna Laframboise, January 12, 2020 in BigPicturesNews


Philip Munday’s work falls to pieces whenever someone tries to verify it.

Last week, Nature published a damning refutation of a significant body of climate change research. The title of that article is self-explanatory: Ocean acidification does not impair the behaviour of coral reef fishes.

The authors studied more than 900 fish from six different species over a period of three years, attempting to verify earlier findings by a team of researchers at Australia’s James Cook University. Their attempts failed.

Scholarly convention being what it is, the now-discredited work isn’t identified in a clear manner. Readers are compelled to sift through footnotes to locate the “several high-profile papers” that are being refuted. So here they are:

….

Continuer la lecture de IPCC Expert’s 8 Discredited Papers

Ocean acidification a big problem — but not for coral reef fish behavior

by Norwegian University of Science and Technology, Jan. 9, 2020 in WUWT


A three-year, comprehensive study of the effects of ocean acidification challenges previous reports that a more acidic ocean will negatively affect coral reef fish behaviour.

The study, conducted by an international coalition led by scientists from Australia and Norway, showed that coral reef fish exposed to CO2 at levels expected by the end of the century did not change their activity levels or ability to avoid predators.

“Contrary to previous studies, we have demonstrated that end-of-century CO2 levels have a negligible impact on the behaviour and sensory systems of coral reef fish,” said Timothy Clark, the lead author of the study and an associate professor at Deakin University in Australia.

Although this is good news on its own, ocean acidification and global warming remain a major problem for coral reefs, the researchers said. Ocean acidification is a problem for creatures that rely on calcium carbonate to make shells and skeletons, such as coral reef organisms, while higher ocean temperatures lead to coral bleaching and death.

..

The Corals That Don’t Exist

by Donna Laframboise, November 18, 2019 in BigPictureNews


In December 2015 Peter Ridd, then a physics professor at Australia’s James Cook University, contacted a journalist. Researchers affiliated with his own institution, he said, were misleading the public about the Great Barrier Reef.

As an example, Ridd cited photos taken approximately 100 years apart near Bowen, a community of 10,000 on the Australian coast in the vicinity of the Reef. These photos tell a stark story: previously vibrant coral expanses are now desolate wastelands.

Ridd complained that this pair of photos was spreading across the Internet. They were appearing in official reports and news stories. Even though the 1995 paper in which they’d first been published had cautioned against viewing them as evidence the Reef was in “broad scale decline,” that’s exactly how they were being used.

Ridd supplied the journalist with recent photos from the same area. These showed healthy, abundant coral.

CRYING WOLF OVER THE GREAT BARRIER REEF

by Peter Ridd, August 12, 2019 in GWPF


The scare stories about the Great Barrier Reef started in the 1960’s when scientist first started work on the reef. They have been crying wolf ever since.

Scientists from James Cook University have just published a paper on the bleaching and death of corals on the Great Barrier Reef (GBR) and were surprised that the death rate was less than they expected because of the adaptability of corals to changing temperatures. It appears as though they exaggerated their original claims and are quietly backtracking. To misquote Oscar Wilde, to exaggerate once is a misfortune, to do it twice looks like carelessness, but to do it repeatedly looks like unforgivable systemic unreliability by some of our major science organisations.

It is a well-known phenomenon that corals can adapt very rapidly to high temperatures and that if you heat corals in one year, they tend to be less susceptible in future years to overheating. It is the reason why corals are one of the least likely species to be affected by climate change, irrespective of whether you believe the climate is changing by natural fluctuations or from human influence.

STRANGE CORAL SPAWNING IMPROVING GREAT BARRIER REEF’S RESILIENCE

by University of Queensland, August 7, 2019 in GWPF


The discovery was made by University of Queensland and CSIRO researchers investigating whether corals that split their spawning over multiple months are more successful at spreading their offspring across different reefs.

Dr Karlo Hock, from UQ’s School of Biological Sciences, said coral mass spawning events are one of the most spectacular events in the oceans.

“They’re incredibly beautiful,” Dr Hock said.

“On Australia’s Great Barrier Reef, all coral colonies typically spawn only once per year, over several nights after the full moon, as the water warms up in late spring.”

Study co-author Dr Christopher Doropoulos from the CSIRO Oceans & Atmosphere said sometimes however, coral split their spawning over two successive months.

“This helps them synchronise their reproduction to the best environmental conditions and moon phases,” he said.

“While reproductive success during split spawning may be lower than usual because it can lead to reduced fertilisation, we found that the release of eggs in two separate smaller events gives the corals a second and improved chance of finding a new home reef.”

The research team brought together multi-disciplinary skills in modelling, coral biology, ecology, and oceanography, simulating the dispersal of coral larvae during these split spawning events, among the more than 3800 reefs that make up the Great Barrier Reef.

Thirty years of unique data reveal what’s really killing coral reefs

by P. Homewood, July 24, 201 in NotatLotofPeopleKnowThat


Coral reefs are considered one of the most threatened ecosystems on the planet and are dying at alarming rates around the world. Scientists attribute coral bleaching and ultimately massive coral death to a number of environmental stressors, in particular, warming water temperatures due to climate change.

A study published in the international journal Marine Biology, reveals what’s really killing coral reefs. With 30 years of unique data from Looe Key Reef in the lower Florida Keys, researchers from Florida Atlantic University’s Harbor Branch Oceanographic Institute and collaborators have discovered that the problem of coral bleaching is not just due to a warming planet, but also a planet that is simultaneously being enriched with reactive nitrogen from multiple sources.

Improperly treated sewage, fertilizers and top soil are elevating nitrogen levels, which are causing phosphorus starvation in the corals, reducing their temperature threshold for “bleaching.” These coral reefs were dying off long before they were impacted by rising water temperatures. This study represents the longest record of reactive nutrients and algae concentrations for coral reefs anywhere in the world.

“Our results provide compelling evidence that nitrogen loading from the Florida Keys and greater Everglades ecosystem caused by humans, rather than warming temperatures, is the primary driver of coral reef degradation at Looe Key Sanctuary Preservation Area during our long-term study,” said Brian Lapointe, Ph.D., senior author and a research professor at FAU’s Harbor Branch.

 

 

https://phys.org/news/2019-07-years-unique-reveal-coral-reefs.html

 

There is the usual armwaving about climate change, but no evidence is presented as to why a small increase in CO2 levels should have the slightest effect on water temperatures or coral development, when the climate has been much warmer for most of the period since the end of the ice age.

As is usually the case with environmental degradation and species decline, it is the obvious factors which are responsible.

What’s really killing the Coral Reefs?

by Carly Cassella, July 20, 2019 in WUWT


Coral reefs are one of the most threatened ecosystems on our planet, and in the past two decades alone, half of the coral in Florida has died off completely. Global warming is known to be a deadly factor, but rising ocean temperatures are only part of the story.

Thirty years of research in the Looe Key Sanctuary Preservation Area (LKSPA) on the southern tip of the Florida Keys has now revealed the cost of a devastating threat to coral that rivals even climate change: direct human pollution.

For years, agricultural run-off and improperly treated sewage have flowed into Florida’s ocean waters from the northern Everglades, elevating the sanctuary’s nitrogen levels and lowering the reef’s temperature threshold for bleaching, researchers say.

As a result of this deadly combination, coral cover in the region has declined from nearly 33 percent in 1984 to less than 6 percent in 2008.

In their analysis, the authors found that three mass bleaching events that occurred during these years only happened after heavy rainfall and increased land-based runoffs. In other words, if we can reduce the amount of local pollution that makes its way into our oceans, we might be able to reduce the worst of the damage.

Klein & Orlando, Bulletin of Marine Science, 1994

New Study Reveals True Cause Of Coral Bleaching (And It’s Not Global Warming)

by Brook Hays, July 16, 2019 in ClimateChangeDispatch


Corals are disappearing across the world’s oceans, and most scientists have pointed to warming water temperatures — the result of climate change — as the primary driver.

But new research suggests nitrogen pollution is the main cause of coral bleaching in Florida.

The study, published this week in the journal Marine Biology, was compiled using the three-decades worth of observational data collected at the Looe Key Reef in the lower Florida Keys.

“Our results provide compelling evidence that nitrogen loading from the Florida Keys and greater Everglades ecosystem caused by humans, rather than warming temperatures, is the primary driver of coral reef degradation at Looe Key Sanctuary Preservation Area,” lead study author Brian Lapointe, research professor at Florida Atlantic University’s Harbor Branch Oceanographic Institute, said in a news release.

Data collected at the test site showed nutrient runoff has boosted the nitrogen-phosphorus ratio in reef algae.

As more and more treated sewage and fertilizers from commercial farms rinse into local waterways and flood the oceans with nutrients, including reactive nitrogen, corals are unable to absorb sufficient levels of phosphorous.

“Our results provide compelling evidence that nitrogen loading from the Florida Keys and greater Everglades ecosystem caused by humans, rather than warming temperatures, is the primary driver of coral reef degradation at Looe Key Sanctuary Preservation Area,” lead study author Brian Lapointe, research professor at Florida Atlantic University’s Harbor Branch Oceanographic Institute, said in a news release.

Des coraux qui s’adaptent aux températures plus élevées

by Paul Berth, 31 mai 2019 in ScienceClimatEnergie


Selon certaines prédictions, basées sur des modèles informatiques, de nombreux récifs coralliens auront disparu des océans tropicaux au cours des 80 prochaines années[1]. La cause est bien évidemment le réchauffement climatique pouvant provoquer un blanchiment des coraux. Par exemple, en 2014–2017, a eu lieu un évènement global de blanchiment, le 3e au cours des 20 dernières années, et de nombreux coraux furent affectés sur des milliers de kilomètres carrés[2],[3]. Les médias, avides de catastrophisme, en ont beaucoup parlé avec des titres une fois de plus très alarmistes (exemple ici).

Cependant, les choses ne sont pas si simples. Des données satellitaires et des études de terrain ont montré que tous les récifs coralliens ne se comportent pas de la même manière: de nombreux récifs n’ont pas blanchi pendant le dernier épisode El Niño, une très grande partie des coraux a résisté au stress thermique, et de fortes variations locales et régionales ont été observées dans le blanchiment[4]. La relation entre température élevée de l’eau de mer et blanchiment des coraux n’est donc pas évidente. Afin d’éclaircir la situation une équipe américaine a récemment publié une analyse globale des évènements de stress thermique en considérant 3351 sites différents dans 81 pays (Sully et al. 2019, dans Nature Communications[5]). Cette analyse globale est unique et démontre que les coraux sont en train de s’adapter par sélection naturelle et sont désormais un peu plus résistants au blanchiment. Nous avons ici une belle démonstration du fait que les modèles informatiques sont parfois bien loin de la réalité de terrain et qu’il ne faut pas tirer de  conclusions toujours hâtives!

Impossible research produces 400-year El Niño record, revealing startling changes

by Charles the moderator, May 7, 2019 in WUWT


University of New South Wales

Melbourne: Australian scientists have developed an innovative method using cores drilled from coral to produce a world first 400-year long seasonal record of El Niño events, a record that many in the field had described as impossible to extract.

The record published today in Nature Geoscience detects different types of El Niño and shows the nature of El Niño events has changed in recent decades.

This understanding of El Niño events is vital because they produce extreme weather across the globe with particularly profound effects on precipitation and temperature extremes in Australia, South East Asia and the Americas.

The 400-year record revealed a clear change in El Niño types, with an increase of Central Pacific El Niño activity in the late 20th Century and suggested future changes to the strength of Eastern Pacific El Niños.

“We are seeing more El Niños forming in the central Pacific Ocean in recent decades, which is unusual across the past 400 years,” said lead author Dr Mandy Freund.

“There are even some early hints that the much stronger Eastern Pacific El Niños, like those that occurred in 1997/98 and 2015/16 may be growing in intensity.”

This extraordinary result was teased out of information about past climate from coral cores spanning the Pacific Ocean, as part of Dr Freund’s PhD research at the University of Melbourne and the Centre of Excellence for Climate Extremes. It was made possible because coral cores – like tree rings – have centuries-long growth patterns and contain isotopes that can tell us a lot about the climate of the past. However, until now, they had not been used to detect the different types of El Niño events.

More Evidence for Rapid Coral Adaptation

by Jim Steele, April 2, 2019 in WUWT


Good news continues to accumulate regards corals’ ability to rapidly adjust to changing climates. The view of coral resilience has been dominated by the narrative of a few scientists. In the 1990s they advocated devastating consequences for coral reefs due to global warming, arguing coral cannot adapt quickly enough. Since the Little Ice Age ended, they believed rising ocean temperatures had brought coral closer to a “bleaching threshold”, a more or less fixed upper temperature limit above which corals cannot survive. Their model predicted the speed of recent global warming “spells catastrophe for tropical marine ecosystems everywhere”. Their assertions that “as much as 95% of the world’s coral may be in danger of being lost by mid-century” was guaranteed to capture headlines and instill public fear. However, a growing body of scientific research increasingly casts doubts on such alarming predictions. Unfortunately, that good news gets much less attention.

A recent peer-reviewed paper titled A Global Analysis of Coral Bleaching Over the Past Two Decades (Sully 2019) compared 20 years of ocean temperatures at which coral bleaching was initiated. From 1998 to 2006, the average sea surface temperature that initiated bleaching was 82.6 °F. But that temperature limit proves not to be “fixed” as earlier researchers incorrectly believed. From 2007 to 2017 the average temperature limit that initiated bleaching was higher, 83.7 °F. This indicates coral have been rapidly adapting to warmer regional climates much faster than once believed.

Coral Reefs in West Hawaiʽi Showing Signs of Recovery

by P. Homewood, February 21, 2019 NotaLotofPeopleKnowThat


Surveys identified 25 coral species in West Hawaiʻi. Lobe coral (Porites lobata), one of the area’s most dominant species, proved to be the most resilient—with only 50% bleaching in 2015. Cauliflower corals (Pocillopora meandrina) were hardest hit—with 98% bleaching—but recent surveys show that they are beginning to recover.