Analysis: Obura et al Coral Bleaching Study: Models Used Misrepresent Warming Rate….”30% Too High”!

From the NoTricksZone

By P Gosselin on 10. December 2021

A German analysis finds that the threatening scenarios about the imminent death of all coral reefs in a recent study cannot be justified. 

The corals off East Africa, doomed to extinction?

By Frank Bosse
Kalte Sonne
(Translated, edited by P. Gosselin)

An agency report startles readers: “All coral reefs in the western Indian Ocean are in danger of dying“. The report refers to this study, which highlights a whole series of risks, such as overfishing in the coming years, which threatens the coral reefs.

How fishing will develop in the next 50 years, however, is still up in the air. Of particular interest is the climatic context, which is also brought to the fore in the reports, as climate models can be used here.

If the water gets too warm, then coral bleaching results.”

In fact, such coral bleaching has been observed again and again, and occurs more frequently at water temperatures above 30°C. This happens now and then locally in the Pacific, especially during El Niño events. So now the total collapse is predicted in 2070.

We took a closer look at the study, focusing on the projected climate stress. The study area is described in Fig. 1 of the study, along with the threats from various factors:

Fig. 1, A reproduction of Fig.1 of the study. Criterion C is what is directly related to climate. However, this determines the particularly vulnerable (red) areas in the final result (left), it is the decisive criterion for the particularly critical spaces.

In the study, an emissions scenario is assumed, it is the one with the second strongest emissions. It provides an additional anthropogenic radiative forcing of 6W/m² by 2100, it is called “RCP 6.0” according to IPCC AR5. RCP 8.5 provides the highest warming, it was deliberately not used in the study, with reference to works that classify it as unrealistic.

Now RCP 6.0 is used. We asked ourselves whether this assumed forcing over the last 40 years corresponds with the observations. The first thing to note is that there are coral reefs at some water depth (up to 60 meters). So the first question is whether the temperatures at the surface are at all representative of these water depths. For this purpose we used the observations of the “Argo” system in the study area (Fig. 1), which also evaluates measurements at water depth.

Fig. 2: Water temperatures down to a depth of 100m between 2004 and 2020 in the observation area. Source: Argo.

We see: Up to about 60 meters, the highest water temperatures of around 28°C occur between February and April (summer in the southern hemisphere) every year. In this respect and in these months, the sea surface temperatures (SST) are therefore representative.

Models overestimate

How well does the mean of the models used (CMIP5) represent the observations of SST?

For a comparison, we restricted ourselves to the months with the highest SST, as they are the decisive ones for the coral bleaching mentioned. We compared the MMM (Multi Model Mean), driven by the RCP 6.0 used in the study, with the observations according to ERSSTv5.

Fig. 3: The observed SST (blue) and the modelled SST (red) with their respective linear trends between 1980 and 2020. Note the peaks in the 1997, 2010 and 2016 El Nino events.

The linear increase of the model mean is 30% higher than the observed one.

The RCP 6.0 scenario used overestimates the observed warming of the last 40 years by 30%.

So the question is: Is a claim on upcoming coral bleaching from climate model observations robust?

In Fig. 1, the particularly endangered areas are also spatially described in great detail. What do models do in this area? We looked at this and compared the spatially resolved correlation of the model mean with the observations:

Fig. 4: The spatial correlation between real observations and the model mean in the evaluation period. In large parts it only reached values below 0.5, which is not a satisfactory result. Chart generated with KNMI Climate Explorer.

The question of whether the models used are really suitable for depicting the conditions off the African east coast around Madagascar must therefore be sent back to the study’s authors.

We conclude: rather not.

The conclusions of the study must therefore be classified as “overconfident” after a critical examination.

The models neither correctly represent the observed warming rate (30% too high), nor its spatial expression. Models with their high uncertainties simply cannot do that. The paper must therefore be classified as descriptive of one of many possibilities.

The headline of the agency report once again conveys threatening scenarios about the imminent death of “all coral reefs”, which cannot be justified or supported.

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Tom Halla
December 11, 2021 2:10 pm

I would doubt claims of extreme sensitivity of corals to warmth, as the Red Sea is warmer than the Indian Ocean, and has flourishing coral.

Reply to  Tom Halla
December 12, 2021 2:49 am

And the Persian Gulf!

Ron Long
December 11, 2021 2:22 pm

When are the Doomsters going to realize that corals are smarter than they are? Don’t wait for it.

Rud Istvan
Reply to  Ron Long
December 11, 2021 2:33 pm

Not to mention they insist that bleaching equals coral death when, as Jim Steele has explained here many times before, that is usually NOT the case.

Reply to  Rud Istvan
December 12, 2021 2:43 am

So does Patrick Moore in his recent book, which also points out that the most diverse coral is found where the water is warmest.

Rud Istvan
December 11, 2021 2:29 pm

Not surprised, but disappointed that this paper even got published. Bosse does a nice job of demolishing it.

Not only does the CMIP5 ensemble run provably hot by about 2x (ECS about 3.4C versus observed 1.7C, neither of the two regional downscaling methods works well (if at all), as Bosse laboriously shows. Both things surely known (or should have been known—the criminal gross negligence standard) to the authors and the reviewers.

Regional downscaling was discussed in Essay ‘Last Cup of Coffee’ in ebook Blowing Smoke published in 2014. That alarm was not about East African coral bleaching, but rather wild Ethiopia arabica coffee variants disappearing from global warming. Same class of false alarm generated by same shoddy methods.

Reply to  Rud Istvan
December 11, 2021 4:19 pm

… disappointed that this paper even got published.

There is the replication crisis. Everyone seems to agree that the majority of published research findings are wrong and can’t be reproduced or replicated. Nobody’s working very hard on fixing this though. Why? Because all the stakeholders (except the taxpayers) profit from the scam.

It’s like the Emperor’s New Clothes where everyone knows full well that the emperor is naked but keep their mouths shut anyway. It’s like everyone knows that everyone else knows but you don’t mention that in polite company.

It is difficult to get a man to understand something when his salary depends upon his not understanding it.

Upton Sinclair

Reply to  Rud Istvan
December 12, 2021 6:51 am

Not surprised, but disappointed that this paper even got published. Bosse does a nice job of demolishing it.” Thanks Rud!

December 11, 2021 3:29 pm

Misunderstood thermodynamics and desperately seeking an anthropogenic signal.

December 11, 2021 3:31 pm

Tropical islands are often made of dead coral and coral sand. So a lot of the corals that grow must turn to tropical islands by some mechanism…could there be a tropical storm surge/ solar exposure/SST /coral death correlation that is millions of years old ? … /s

Rud Istvan
Reply to  DMacKenzie
December 11, 2021 3:52 pm

Parrot fish.

Reply to  Rud Istvan
December 11, 2021 10:10 pm

Parrotfish poo for clarification

December 11, 2021 5:01 pm

The communist climate cult are all fraudsters
How about that hockey stick guy. Can you believe he still gets work, and cited?

Dave Fair
Reply to  Matt
December 11, 2021 5:39 pm

He makes State Pen (home of the money-driven whitewashes of Sandusky and Mann) alot of taxpayer money for their bloated bureaucracy. He is a pit bull darling (among many others) of the CliSciFi profiteers in government, academia and NGOs and crony capitalists of all stripes.

December 11, 2021 5:35 pm

All coral reefs in the western Indian Ocean are in danger of dying.

Actually, all living species everywhere on earth are in danger of dying. Each and every day. No need to get selective about it. It has always been so.

Time to face facts. 99.99% of all species that ever lived are already extinct. There is no hope that any species will ever escape this fate. All it takes is one gamma ray burster in the local group. Eventually, the Sun will expand into a red giant anyway and the earth too, will become cinders in space.

In the meantime, be sure to send your check to some concerned group who will work diligently to fight the inevitable.

Dave Fair
Reply to  Doonman
December 11, 2021 5:41 pm

All my money went to the Polar Bears and all I got was this half-eaten seal on thick ice.

December 11, 2021 8:18 pm

Currently diving in the Maldives where I have been going for 28 years and the coral is better in many places than I have ever seen it. There is a lot of new growth and a very healthy fish population. It is noticeable that the first place that seems to get new growth is in the lagoons inside the fringing reefs where the temperature is generally higher. The deeper (20m or so) corals are looking really good. These does seem to be less algae growing over the corals, maybe the protection of parrot fish is helping?
Most damage on the house reefs seems to come from people standing on it or kicking it with their fins as the snorkel!

Dave Andrews
December 12, 2021 6:28 am

Don’t forget the US tried to nuke Bikini Atoll to death but didn’t succeed!

Reply to  Dave Andrews
December 12, 2021 10:09 am

Yes, what a real-life study in the resilience of corals THAT indisputable story provides.

(but predictably avoided by the media)

Joao Martins
December 12, 2021 9:58 am

The abstract of that article (the abstract!) starts with an unsubstantiated assertion: “Ecosystems worldwide are under increasing threat.”

Stopped reading at the end of this sentence, the first after the title.

The abstarct of an article should have the exaxt short summary of the contents; it should not have vage sentences that do not correspond to or outcome from what has been done or observed and is described and discussed in the paper. Writting an abstract like this is professional malpractice.

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