The “GBR Swindle” revisited – response to Peter Ridd

It seems that “The Great Barrier Reef Swindle” and my subsequent response generated a fair amount of debate throughout the blog world and the scientific community. Dr Ridd has posted his response to the my comments regarding the science behind the response here, and in keeping with the science and debate, see my response below.

Before I go into detail on this, attached is one of the paired photographs from the inshore reefs in Bowen, Queensland detailing local scale changes on the Great Barrier Reef during the 20th century (photographs speak louder than words):


Dear Peter,

Thank you for clarifying your position. I suppose my first comment relates to your first statement that you “did not say that there is some cover up regarding the health of the GBR”. I suppose I’m little flabbergasted given that the title of your article was “The Great Barrier Reef Swindle” and that your opinion piece was peppered with statements of the ilk “. Closer to home, there is a swindle by scientists, politicians and most green organisations regarding the health of the Great Barrier Reef (GBR)”. Even if you strictly did not mention “cover-up”, I think the implications from swindle and the associated concepts you trot out in your article are the equivalent of this. Few would disagree.

But, let’s leave that issue alone and concentrate on the particular scientific issues that you bring out in response to my comment on your opinion piece.

1 “corals are more tolerant to rising waters temperatures than first thought by most people”

My disagreement with the way that you portrayed the article by Dr Madeleine van Oppen and Jos Mieog is that you implied that the science that was being presented in the article credibly disproved, or contributed to the disproof of, the evidence that the rapid changes in sea temperature on coral reefs were a problem. Perhaps you were not to blame for all of the spin in this case, but I think it’s significant that the senior investigator of the paper chose to distance herself from the interpretation that they had shown that corals “are more tolerant to rising water temperatures than first thought by most people”.

Your statement “This is also not the first time that evidence been gathered that indicate that corals can respond relatively quickly to temperature changes by taking on different strains of zooxanthellae.” belies a certain lack of knowledge of the issue within the literature. I direct you to a series of articles that equally show that this hypothesis is largely unsupported (Goulet 2006; Goulet and Coffroth 2003)

2 Corals and Cockroaches

You comment that I have misrepresented your comments on the similarity between canaries and cockroaches. If you read carefully what I had written – I actually agreed with you that corals in geological time are not delicate organisms. However, Lyndon DeVantier, points out that even that statement needs qualification that not all corals have large distributions and huge dispersal characteristics – that many are not as robust in evolutionary time as my over-generalisation would have it.

3 Some like it hot.

And this gets me to your third comment in regard to “some like it hot”. Your point about the growth rate of massive corals increasing over the last century is only true up until 1985. There are two data sets that I know of that are currently in review which show a downturn in the growth of these same massive corals since 1985. I will discuss them when they are finally published. They show, like almost all organisms we know, that growth is stimulated by temperature up to a certain point. However, when you reach a high enough point, stress kicks in and growth rates decline. Classic stuff really.

In the meantime, if one looks at the data from the surveys that are done each year by the Australian Institute of Marine Science, you will find that not all reefs have recovered from the 1998, 2002 and 2006 bleaching events. Lastly, I can’t see what data you are referring to when you say “I think it highly unlikely that the hard cutoffs threshold for bleaching that Prof HG talks of are genuine.” If that were true, then the NOAA satellite ‘Hotspot’ program would be unable to predict bleaching by using anomalies in sea surface temperature.

Your last comment “An organism that has seen so much climate change over the eons is unlikely to have a weakness like a not adaptive thermal threshold.” mixes two concepts. The first is physiological responses to the here and now (ecological, days, months), versus the relatively slower adaptive responses that organisms make to changing conditions (decades to centuries). Corals have adapted to see temperature in the past but this has taken large amounts of time (much more than the short time frame over which the current rapid changes in sea temperature occurring).

4 Climates have changed before.

It is unfortunate but common mythology propagated by some that the current rates of climate change (last 50-100 years) are not unusual relative to the rate of changes seen over the past several million years.

The calculation to demonstrate that this is not so is rather simple. Let’s take a conservative view of recent temperature change and say that we have had a 1° change in global temperature over the past 100 years. (i.e. 0.01 °C per year). If we can assume that it talk 10,000 years for the earth’s temperatures to move from the last ice age to the interglacial – then we are talking about 6°C over 10,000 years (i.e. 0.0006°C per year). Now, these numbers are rough but highly conservative (if you talk about 4°C rise over the coming century, the difference becomes even more stark) and they demonstrate why biological systems may have trouble keeping up (i.e. it takes time for organisms to migrate from region to region etc; for the effect of natural selection take place etc).

I’m not going to deal with your out of date comment that the absolute temperatures that we see today are not outside those seen in the last thousand years, primarily because the arguments are made more succinctly elsewhere in and the data simply do not support your conjecture. I would refer you to the extensive literature showing the reverse is — Peter, I would start with the fourth assessment report of the IPCC and articles like Jones et al (2007).

5 Have we been swindled

The peer review process is certainly a tough process. In terms of our ability as a society to discern between spin, loose facts and real science, the peer review process is really the only thing that we can depend on. It is hardly perfect — but largely, if the idea is good and it is supported by hard science, a good idea will be published. I am sorry to hear about your trials and tribulations in trying to get your ideas into the peer reviewed literature. However, if your papers have the problems that we have been discussing so far, I can see why they wouldn’t pass muster with anonymous peer review because they are largely conjecture (i.e. GBR scientists are swindlers) and are not based on hard data. I reiterate the point that this is not about a club of scientists who want to feather their own nests but rather the process of science. Again, if one had really good data to show that climate change was either not happening all was not related to human activities, then I believe that it would be no trouble to get them published — and there would be huge rewards to scientists that could show that.

Re: Heretics that cant publish their ideas.

I think that all scientists are heretics at heart, and no one finds publication easy (especially given the rigour that is involved). I also think that these outlets (blogs etc) are important — but equally so, I think we have to be cognizant that these outlets are a great place for discussing ideas but they fall far short of the requirements of evidence of the peer-reviewed literature.

Finally, in response to your point that “the GBR is probably the most intact and least impacted ecosystem on earth with the exception of Antarctica” all I can say is that I agree (as does Pandolfi et al. 2003 if you read it carefully). But this is relative term. The problem is that despite the best in management practices in the world, the GBR is changing (see matched set photos above). Given what we’ve seen around the rest of the world, for coral reefs in places close to human settlements and further away, there is a lot to be concerned about — I don’t know any reason why we should be complacent that the GBR is somehow immune from global change and other an insidious human impacts.

4 thoughts on “The “GBR Swindle” revisited – response to Peter Ridd

  1. Three comments.
    Inshore reefs are subject to occasional devastation from storms, floods and temperature extremes. I have observed individual reefs go from lush coral cover to rubble, recover over a period of 5 or 6 years, look great for several years and be returned to rubble. The photos shown may or may not depict any long term degradation.

    The warm water associated with coral bleaching is not the result of unusually hot weather but extended periods of calm conditions that permit the surface layer to heat up without mixing by waves. Climate models project increased winds with increased AGW.

    Reefs are often subject to dramatic natural fluctuations from a variety of causes. In recent years there has been a tendency for any observed change to be immediately attributed to detrimental anthropogenic effects. Such pronouncements tend to reveal more about the naivety of biologists than about the actual condition of a reef.

  2. Commenting on what Walter Starck had to say (I will leave his second point for someone else to pick up):

    1) Inshore reefs are subject to occasional devastation from storms, floods and temperature extremes. I have observed individual reefs go from lush coral cover to rubble, recover over a period of 5 or 6 years, look great for several years and be returned to rubble. The photos shown may or may not depict any long term degradation.

    The original data-set for the photographs I believe is from Dr David Wachenfeld at GBRMPA (and currently being expanded upon by others) – “Long-term trends in the status of coral reef-flat benthos – The use of historical photographs” ( – see also the recently released Status of Near-Shore Reefs of the Great Barrier Reef 2004 (

    Indeed, ‘modern’ coral communities from the GBR developed during the mid-late Holocene, in a disturbance regime dominated by cyclones and flood events (and indeed, such disturbance is important in maintaining the high levels of diversity). On the outer-shelf reefs of the GBR, work by Dr Terry Done from AIMS has shown that following COT’s outbreaks in the late 1980’s, reefs undergo phase shifts from coral dominated communities to algal dominated communities, yet show remarkable resilience in that reefs recovered to pre-disturbance levels in a relatively short time period (6-10yrs). However, evidence is accumulating that inshore reefs are undergoing persistent phase shifts, with losses of previously dominant Acroporid communities and local removal of coral species – this is our cause for concern. As Done saliently points out:

    “…it is this spectre of a persistent shift to either of these alternative states (macroalgal reefs / barren eroded reefs) … that is of great concern on inshore reefs of the Great Barrier Reef, not the periodic death of corals per se”.

    Whilst I appreciate that the photographs “may or may not” depict any long term degradation, the impacts upon the inshore reefs of the GBR are based upon considerably more than just the paired photographs. Lyndon DeVantier recently released a study of the inshore GBR reefs, and highlighted a significant shift in coral communities within the Wet Tropics region (16-18°S), where coral species richness was between 41-67% lower than adjacent inshore regions, and concluded that “this was probably due to the disturbance regime, with an apparent anthropogenic component” (Coral Reefs 25 329 – 340).


    2) Reefs are often subject to dramatic natural fluctuations from a variety of causes. In recent years there has been a tendency for any observed change to be immediately attributed to detrimental anthropogenic effects. Such pronouncements tend to reveal more about the naivety of biologists than about the actual condition of a reef.

    Since European settlement of the Queensland coastline in the mid 18thC, extensive land use changes in the GBR catchment region have occurred (resulting from grazing, agriculture and land clearance). If anything, I feel that it is somewhat naive to suggest that such detrimental anthropogenic effects have not had an impact on the inshore reefs of the GBR. Whilst I understand your point, this is not simply ” the naivety of the biologists” – see the meta-analysis by Bellwood et al (2004) detailing significant declines in coral cover on the GBR from the 60’s to present day (Nature 429 827 – 833).

    There is strong evidence (both direct and indirect) for anthropogenic impacts on the inshore reefs of the GBR – this has been debated considerably within the literature. Humans are well known to alter both the temporal and spatial scales of natural disturbance regimes (in addition to introducing novel disturbance events) thereby impacting upon the potential of reefs to recover following disturbance. In this sense, it is difficult to separate “dramatic natural fluctuations” from “detrimental anthropogenic effects”. Although there is a distinct lack of knowledge regarding the historical ecology of coral communities and a baseline with which to compare corals prior to European settlement with current coral communities (we are working on this), see Pandolfi et al (2003) evidencing long-term decline and degredation of reefs from the inshore GBR (Science 301 955 – 958).


  3. Walter – I covered this to some extent in an earlier post (refer to post on hurricanes and coral bleaching, July 6th) – severe mass coral bleaching results from extended periods of calm weather (doldrums) which are now reaching higher sea temperatures than they did in the past due to the waters of the Great Barrier Reef being about a degree warmer than they were 100 years ago. This increase in background temperatures is pushing temperatures across the thermal threshold of corals (e.g. 1998, 2002 mass bleaching events on the GBR).

    I think it is questionable at best to suggest that increased wind speeds predicted by the IPCC will offset or counteract the projected rises in sea surface temperatures. It may have localised impacts. Against this conjecture is the observed increase in the frequency and severity of coral bleaching on the GBR in the past 2 decades.

  4. 2 Corals and Cockroaches
    I think there is no major disagreement between Prof H.G and myself on the analogy between cockroaches and corals. We seem to agree that both organisms are tough but not indestructible. Corals have certainly done it tough over the ages – especially during cool periods.
    The problem lies not with the cockroach but with the canary. Clearly from the scientific viewpoint the canary analogy is useless except in terms of spectacular colour. It is much less appropriate than the cockroach analogy. Canaries are invoked primarily for publicity purposes to persuade the public of the dangers of global warming on climate change. It is an emotive argument, not based in any facts, and gives the wrong impression of the sensitivity of corals to change.
    3 Some like it hot.
    I do not dispute that at a particular location and time, there is a clear hard cut-off where corals will bleach. This has been one of the major successes of the science in this area and Prof H.G has obviously been at the forefront of this research. The argument comes down to whether they can change rapidly enough to cope with warming and whether the warming we have so far seen is actually faster than what has occurred in the near past. On this we clearly disagree (see below)
    4 Climates have changed before.

    Prof H.G refers to the wrong part of the geological record and also to the wrong time scale when he looks at rates of change. Certainly the general rise in temperature (averaged over a few hundred of years) at the end of the little ice age was slow (though Prof H.G has considerably exaggerated this in his figures), but a feature of geological climate records is that they are often highly variable at all time scales. It would be brave to presume that the temperature rose at the end of the last ice age by a nice and gentle steady rate. (
    The time scale of interest is over decades. A look at modern temperature proxies and even instrumental proxies indicate that a temperature change rate of 0.010C/year (rise or fall) is common, if not the norm. Such a rate of temperature change is in the same order as we presently see.

    Prof HG may not believe the proxy records that show the rapid temperature fluctuations associated with the little ice age and the medieval warm period (see above sites) as it has become a hotly disputed topic that goes to the heart of the IPCC claims about climate change. But we need not go into that debate here as the instrumental records show a very similar rate of warming in the early part of this century (1900 to 1940) as it did in the latter part of the century. Considering that the CO2 production in the early part of the 20th century was far less than at the end of the century it is quite possible (I believe probable) that most of the warming in the early 20th century is natural and running at the standard 0.010C rate (see
    From this I think it unreasonable to conclude that the rates of temperature change we have thus far seen are anything extraordinary and I would further suggest that the absolute temperatures are not unusual considering the Holocene climatic optimum and the medieval warm period.
    That brings us to the future and if the high end predictions of the IPCC are correct. I agree that Prof H.G’s figure of 4 degree in 100 years would cause significant damage, at least in the short term to the GBR, though I would not be surpised if in a few hundred years after, the GBR would be in better shape than it is today particularly if sea level rise covered the reef flats such as shown in Prof HG’s photograph in this post. The point is that with a 4 degree rise in 100 years, the damage to the GBR will be the least of our environmental, social and economic concerns. It will be the system that will get through the best. It is an open system not bounded by natural and unnatural borders.

    5 Have we been swindled
    I was interested that Prof H.G agrees that the GBR is one of the best preserved ecosystems in the world. This seems at odds with the view that the public has now got. The general public have been told repeatedly that not only is the GBR to be completely wiped out in the coming couple of decades, but that it is already seriously degraded. The paper by Pandolfi eta l (2003) I quoted previously is a case in point, but there are numerous examples of this exaggeration in the public arena.
    In this sense the public have been swindled into believing the GBR is in much worse state that it really is. Perhaps I would in retrospect avoid the word swindle and replace it with misinformed (both deliberate and otherwise)
    I would not mind if these exaggerations only occasionally surface, but it seems to be a continuous stream and much of it is deliberate. Prof H.G’s recently publicity about the cold water bleaching event is a case in point. It is remarkable that Prof HG blames this on climate change and thus implies that not only are the corals going to die because it is too hot, but also they will die from the cold. In reality this is just an unusual event and by itself says nothing about climate. It says much more about our limited understanding of corals, their ability to cope with extremes, and our lack of knowledge of the response of corals to previous extreme events.
    The pair of photo’s Prof H.G uses at the beginning of this post is another example of willful manipulation of the science. We could just as easily show pictures showing regeneration of coral. Such a pair would not show that the reef is in great shape. In highly variable systems these single data points are meaningless as science but powerful P.R tools.

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