Coral Calcification and Photosynthesis in a CO2-Enriched World of the Future

I must admit, the first time I saw this article I nearly fell out of my chair. Entitled "Coral Calcification and Photosynthesis in a CO2-Enriched World of the Future", the article attempts to make sense of a recent publication by Lydie Herfort et al entitled "Biocarbonate stimulation of calcification and photosynthesis in two hermatypic corals" by providing a stereotypical ‘skeptic’ view:

"As ever more pertinent evidence accumulates, however, the true story appears to be just the opposite of what these climate alarmists continue to tell us."

Odd how that it is always the exception to the rule is the ‘true’ story – ignoring the vast quantity of peer-reviewed literature on the topic. A bit of background here: as part of the "Centre for the Study of Carbon Dioxide and Global Change", the Idso family (Craig, Keith and Sherwood) publish a pseudo-journal entitled CO2 Science (see here for their ‘interpretations’ on other recent coral publications). A little digging reveals that the Centre (of which Craig is the chairman and founder and Sherwood the president) is part funded by Exxon (amongst other sources). Not that this in itself is much of an issue (or indeed much of a surprise), as Sherwood Idso views it:

"It is self-evident, for example, that one need not know from whence a person’s or organization’s funding comes in order to evaluate the reasonableness of what they say, if – and this is a very important qualification – one carefully studies the writings of people on both sides of the issue"

The key problem here is that the Idso et al seem to have a fairly obvious agenda, which couldn’t be further from addressing both sides of the issue:

"As for the real-world implications of their work, the three researchers note that over the next century the predicted increase in atmospheric CO2 concentration "will result in about a 15% increase in oceanic HCO3," and they say that this development "could stimulate photosynthesis and calcification in a wide variety of hermatypic corals." This well-supported conclusion stands in stark contrast to the outworn contention of the world’s climate alarmists that continued increases in the air’s CO2 content will, as restated by Herfort et al., "cause a reduction in coral growth and planktonic calcification." This claim, as they and many others have now demonstrated, is about as far from the truth as it could possibly be."

This doesn’t quite ring true – along with paraphrasing the original article by Hertfort et al. (2008), Idso et al seem to have missed the point entirely. Here is a response from Dr Ken Anthony, an expert in ocean acidification and Alicia Crawley, a PhD student working on ocean acidifiation and coral photosynthesis in our lab:

In a recent article in the website CO2 Science, Idso et al. (2008) used the results of a controlled bicarbonate-enrichment experiment to argue that ocean acidification is not a problem for corals reefs. Interestingly, the experiment by Herfort et al. (2008) was not an ocean-acidification experiment. Ooops. So, from any scientific or even logical standpoint, Idso et al. (2008) have no argument whatsoever.

Herfort’s experiment focused on the effects of increasing bicarbonate concentrations on rates of photosynthesis and calcification of coral reef organisms. I hear some of you ask: “But, is that not the same as ocean acidification?” Well, in a nutshell – no. Ocean acidification is the result of declining pH caused by the uptake of atmospheric CO2. Herfort et al. kept their pH (the parameter that determines acidity) constant at 8.2 across all treatments. This also means that Herfort’s results are totally irrelevant to the major problems of ocean acidification – (1) carbonate saturation state and (2) acidosis of cellular mechanisms such as photosynthesis.

The lowered pH from ocean acidification leads to low concentrations of carbonate ions, the building blocks of all marine calcifying organisms, which can lead to critically low rates of calcification and even shift to net rates of calcium carbonate dissolution. Also, the proper functioning of cellular mechanisms such as photosynthesis are sensitive to pH change, so keeping pH constant would not capture those stresses.

Bottom line, Herforts’ experiment did the opposite of any realistic future scenario: by keeping pH constant while increasing bicarbonate (HCO3-) concentrations they boosted carbonate ion (CO3=) concentrations and thereby rates of calcification, and ignored any effects of acidosis. Idso et al (2008) is another sad example of uninformed propaganda, running with one of two sentences from a study they do not comprehend – and then leaping to their own naive conclusion that the overwhelming amount of good science predicting negative effects of ocean acidification, is simply alarmist.

In the interest of science, I’d like to openly invite Craig, Sherwood or Keith Idso to defend their critique in light of this, and would be very interested to hear the perspective of Lydie Herfort and authors as to the rather open interpretation of their paper by others.

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