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Coral Bleaching Just As Bad In 18thC

August 16, 2018

By Paul Homewood


A new study finds that coral bleaching on the Great Barrier Reef is nothing new.

From the Evening Express:


Large-scale coral bleaching has raised concern about the future of the ecosystems and the impact their loss could have on biodiversity.

The fact that we are seeing an increase in bleaching even in these tough corals highlights just how serious the threat of coral bleaching is

Dr Sebastian Hennige, researcher


The teams found the frequency of bleaching has increased since the 1800s and, despite corals’ ability to recover, there are fears they could now be approaching a “critical threshold”.

Dr Nick Kamenos from Glasgow’s School of Geographical and Earth Sciences said: “It’s clear in the core data we examined that bleaching has been occurring on the Great Barrier Reef for at least 400 years, but the frequency of bleaching events has increased markedly since the early 1800s and those events have affected 10% more corals since the late 1700s.

“We can see that corals have been able to acclimate and recover from past bleaching events.

“However, the increase in bleaching frequency and the numbers of corals affected since temperatures started consistently increasing in the modern era raises serious concerns about whether corals are approaching a critical threshold beyond which their long-term survival is uncertain.”

Bleaching occurs when water temperatures rise too high and disrupt the relationship between the coral and the tiny algae living inside it.

When the algae are expelled, it leaves the coral a stark white. They can be reabsorbed when the water temperature drops again, but corals die if this separation is too long.

Dr Sebastian Hennige from Edinburgh’s School of Geosciences said: “For this study we used the most conservative methods we could in some of the toughest corals out there today.

“The fact that we are seeing an increase in bleaching even in these tough corals highlights just how serious the threat of coral bleaching is, and how important it is that we take action now to reduce this threat.”

The paper, titled Reconstructing four centuries of temperature-induced coral bleaching on the Great Barrier Reef, is published in the journal Frontiers.

The study was supported by funding from the Natural Environment Research Council, the Royal Society of Edinburgh and the Scottish Government.


The claim that the frequency of bleaching events has increased markedly since the early 1800s is an utterly dishonest one. Here is the actual graph from the paper itself:




The relevant chart is “B”, which shows the number of years in each decade when at least 20% of corals were affected. As you can see, although there has been a rise since 1800, there is little difference between recent decades and the 18thC. Indeed bleaching was far worse in the 1890s and 1750s.

Worse still for the alarmists, chart “C” shows little change in the percentage of corals bleached per decade.

There is the usual nonsense about how things will get much worse. But the actual facts show a completely different picture.

  1. August 16, 2018 12:39 pm

    It’s as if their research didn’t show what they expected. So they decided to lie, knowing full well 97% would never read the actual paper.

  2. August 16, 2018 1:06 pm

    Not to mention the fact that it is the sun that warms the oceans, not an increase in that old greenhouse gas, CO2.

    • Graeme No.3 permalink
      August 16, 2018 1:25 pm

      What Graph B does show is the effect of lower sea level during the Maunder minimum, followed by the increase in temperatures until (roughly) the cold winter of 1740, followed by colder climate through the Dalton Minimum. Then in turn the warming since 1850 with possible adverse effects in the colder 1890s and 1960’s. Doesn’t say anything about CO2.

      • Ian Magness permalink
        August 16, 2018 1:44 pm

        Absolutely agreed Graeme. I would however add ENSOs into the mix. If anyone wonders why the GBR bleaching is so often referred to in AGW-sponsoring papers, it is because the particular geographic location of the GBR makes it, especially parts of it, especially exposed to the sea level fluctuations that occur as a result of ENSO cycles. The lowered sea level phases can create faster and more powerful bleaching processes than that applicable to global sea surface temperature variations that many scientists believe corals can cope with anyway. Other reefs in the world are less affected during ENSO cycles but, naturally, aren’t as much fun to comment on if you wish to promote AGW.

  3. Broadlands permalink
    August 16, 2018 1:21 pm

    We have been over all this nonsense before. The sea water temperatures on the Great Barrier Reef have not been unusual.

    • Graeme No.3 permalink
      August 16, 2018 1:26 pm

      Ah! But the air temperatures have been raised by lots of hot air from grant seeking ‘scientists’.

  4. Jeff permalink
    August 16, 2018 1:39 pm

    The millions they are wasting on “saving” the barrier reef is an absolute joke.

  5. August 16, 2018 2:29 pm

    Reblogged this on Climate Collections.

  6. roger permalink
    August 16, 2018 4:36 pm

    Why is the university of Glasgow obsessed by events which may or may not be happening on the other side of the world in the backyard of another country, many times the size of Scotland, which has it’s own plethora of Universities studying the same non event?
    I would have thought that real events close to home, having a catastrophic effect on the Scottish economy outside of the central belt would be more deserving of their scientific
    Salmon and sea trout in rivers and lochs on the west coast of Scotland have been in serious decline for decades to the extent that rod and line fishing and netting in the sea have been either banned or curtailed to such an extent that few now come to fish here.
    These draconian measures do not affect the east coast rivers where catches have held up well.
    May I suggest a useful line of research might be the effect of the AMO and the NAO on Atlantic populations when compared to the North Sea and whether there might be a causal correlation with Pacific salmonid population fluctuations that have chimed for centuries with the PDO.
    Or could it just be that the sea lice burden generated by Norwegian owned salmon farms throughout the west coast is attaching to smolts on their migration to feeding grounds off Iceland and Greenland?
    Or it could just be that the Scottish council knows the answer and like all politicians would rather we did not.

    • August 16, 2018 5:16 pm


      • martinbrumby permalink
        August 17, 2018 8:44 am

        Not just money.
        Don’t forget the nice tax-payer funded holidays scuba diving on the Great Barrier Reef.
        Very enjoyable, even when you pay everything out of your own pocket!

  7. Geoff Sherrington permalink
    August 17, 2018 6:27 am

    For those seeking actual data on which to work, here is a URL that gets you into the data base of the Australian Institute of Marine Science. The example given here is for Heron Island, on the Tropic of Capricorn, the southernmost long term station on the Barrier Reef. The parameters can be chosen interactively to access other sites and measurements.
    One early impression that might strike you is the tiny amount of water temperature variation from year to year. One has to suppose that just one or two really anomalous hot days are required to do the damage; and since the mechanisms that create these sporadic hot days are not known, remediation would seem to be no more than waving a hand in the darkness of ignorance. Geoff,189

  8. August 17, 2018 9:22 am

    Reblogged this on Tallbloke's Talkshop and commented:
    Many believe the forces of climate alarm got Professor Peter Ridd fired for saying what he thought about the recovery powers of the GBR.

  9. stpaulchuck permalink
    August 17, 2018 2:32 pm

    corals have been around for millions of years (billions?) and have weathered ice ages and interglacials and are still with us in abundance. Just another rent seeking broadside for the cheapseats.

  10. Bitter@twisted permalink
    August 17, 2018 6:02 pm

    Here’s me thinking that when I write a paper (as I am right now), the conclusions must be supported by the results.
    But HEY! This is climate science.
    The rules must be different.

    Really, really sucks.

  11. August 17, 2018 6:58 pm

    Thank you. In Australia, the professor drummed out of his job for having an alternate view has been rewarded with a sizesble grant to continue his work. I’m sure you can find the details. I think the PM took the responsibility to rectify the error.

  12. Broadlands permalink
    August 17, 2018 10:40 pm

    Can someone please wake up this guy?

    What an amazing pile of human waste products?

  13. tom0mason permalink
    August 18, 2018 5:04 pm

    “The teams found the frequency of bleaching has increased since the 1800s and, despite corals’ ability to recover, there are fears they could now be approaching a “critical threshold”.

    So by looking as a very short time period in the reefs existence they “believe” “they could now be approaching a “critical threshold”. Not overly scientific a mere conjecture considering how long coral have survived in the seas and oceans.


    ” The Great Barrier Reef Marine Park Authority (GBRMPA) considers the earliest evidence of complete reef structures to have been 600,000 years ago.[24] According to the GBRMPA, the current, living reef structure is believed to have begun growing on the older platform about 20,000 years ago.[24] The Australian Institute of Marine Science agrees, placing the beginning of the growth of the current reef at the time of the Last Glacial Maximum. At around that time, sea level was 120 metres (390 ft) lower than it is today.”

    So I presume that during all that time it has suffered more stress and temperature variation then the pifflingly slight amount it currently has to endure.

    Who is to say that this bleaching is not a survival tactic by the coral polyps, whereby it sheds less efficient symbiotic organisms for better ones during this process?
    Also as just about all life in the seas and oceans are affected by the lunar cycles, could this process be linked to some unknown effects of the solar/lunar cycle, as well as temperature, ocean chemistry, and other biotic processes?
    With so little known about these creatures surely it is very premature to surmise that they are about to become very threatened by such small changes in the biosphere. These are very tough and resilient creatures as witnessed by the coral recovery in the H-Bomb area of Bikini Islands ( ).

  14. August 18, 2018 8:25 pm

    Paul – sorry I didn’t see this sooner. Just looking thru the study. How in the world can they do this and not a single time draw attention to el Nino events? Notably the great 1877-78 el Nino?

    After all, it’s the more rapid changes in temperature that result in the most notable bleaching events.


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