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A Shell Game Behind Ocean Acidification?

This is the story of how field data showing higher CO2 concentrations in the past is what probably lies behind the increasingly louder alarm calls about ocean acidification in the future.

The story ends with the “Monaco Declaration” and “more then 150 top marine researchers” voicing “their concerns [that] he world’s marine ecosystems risk being severely damaged by ocean acidification unless there are dramatic cuts in CO2 emissions“, as per this recent BBC story.

The story starts with two articles by “Pearson and Palmer” in Science (1999) and Nature (2000):

(1) Pearson, P.N. and Palmer, M.R. 1999. Middle Eocene seawater pH and atmospheric carbon dioxide concentrations. Science 284: 1824-1826

(2) Pearson, P.N. and Palmer, M.R. 2000. Atmospheric carbon dioxide concentrations over the past 60 million years. Nature 406: 695-699

According to (1) , “[…] construction of a pH profile for the middle Eocene tropical Pacific Ocean shows that atmospheric pCO2 was probably similar to modern concentrations or slightly higher”.

The abstract in (2) reads “[…] We estimate CO2 concentrations of more than 2,000 p.p.m. for the late Palaeocene and earliest Eocene periods (from about 60 to 52 Myr ago) […] Since the early Miocene (about 24 Myr ago), atmospheric CO2 concentrations appear to have remained below 500 p.p.m. and were more stable than before, although transient intervals of CO2 reduction may have occurred during periods of rapid cooling approximately 15 and 3 Myr ago“.

Lest we forget, it is commonly accepted that CO2 changes follow temperature. Anyway, the two Pearson and Palmer papers show:

  • a +5C warmer Earth than today during the Eocene, for an estimated 385ppmv of CO2 (min:180; max:550)
  • hence, either an extreme climate sensitivity or more likely “that the global cooling since the Eocene was not driven primarily by changes in pCO
  • large variations in atmospheric CO2 concentrations not exactly associated to incredible bloomings or mass extinctions in marine life

It would appear obvious that the above is no basis for any concern about marine life and acidification caused by increased CO2 concentrations. So how does one get from start to apparently contradictory end?

Here’s how. Let’s trace the path backwards.

[i] On the side of the BBC article, follow the link to “The Ocean Acidification Network“.

[ii] Click on “How is the ocean acidity changing?” and look at the graph.

[iii] Note the huge swing 1800-2000, covering almost the whole range experienced during the past 25 million years.

[iv] The caption says “From Pearson and Palmer, adapted by Turley et al. and from the Eur-Oceans Fact Sheet No. 7, “Ocean Acidification – the other half of the CO2 problem”, May 2007“.

[v] The Pearson and Palmer reference is (2) above. The Turley reference is:

(3) Turley, C., et al. (2006), Reviewing the Impact of Increased Atmospheric CO2 on Oceanic pH and the Marine Ecosystem, in Avoiding Dangerous Climate Change, 65-70, Cambridge University Press

[vi] Parts of that book are available via Google, and in particular most of the Turley et al. contribution, with a page with that exact graph.

[vii] Note the respective sources for the values displayed:

  • Points before 1800 are defined in (3) as “Past…variability of marine pH” with a reference once again to Pearson and Palmer from 2000 (once again, reference (2) above).
  • The values for 1800 and 2000 are defined as “contemporary variability of marine pH” (i.e. the huge swing as per step [iii] above).
  • The 2050 and 2100 diamonds are “model derived…based on IPCC mean scenarios“.

[viii] What could those models be? Look at “Ocean Acidification” on Wikipedia. The main reference for future predictions is this Orr et al.’s article in Nature in 2005:

(4) Orr, J.C. et al. Anthropogenic ocean acidification over the twenty-first century and its impact on calcifying organisms, Nature 437, 681-686 (29 September 2005) (full text)

[ix] Look at the caption of figure 1 in the full text. Orr et al. write that they estimate “pre-modern DIC” (dissolved inorganic carbon) “by subtracting data-based anthropogenic DIC […] as well as by subtracting model-based anthropogenic DIC“.

[x] The authors refer the readers to the “Supplementary Info” for their article (full text). Therein they mention this 2004 Science article:

(5) Sabine C.L. et al., “The Oceanic Sink for Anthropogenic CO2“, Science 16 July 2004 Vol. 305. no. 5682, pp. 367 – 371

[xi] Interestingly, Sabine et al. write the following in response to a comment about (5): “Our assessment of the impact of climate change on the ocean carbon inventory applies only to the past 200 years“.

[xii] In other words, the estimates done by Orr et al. for 1800 are at the very edge of visibility.

This means that the huge swing as of step [iii] may actually be an artifact of analysis.


In summary:

  • even if past data suggests that the oceans can cope reasonably well with very large variations in atmospheric CO2 concentrations (1) (2),
  • that same data is taken as evidence of future ocean acidification,
  • using a graph from an article that estimates ocean pH between 1800 and 2100 (3)
  • based on a work that compares pre-modern and modern marine CO2 concentrations (4)
  • according to another work whose results barely cover the whole period (5).

A swift sleight of hand in some kind of peer-reviewed shell game, perhaps?

0 replies on “A Shell Game Behind Ocean Acidification?”

I am wondering if very large scale development of oyster farms might help remove the carbonic acid turning it into sea shells.

At the turn of last century, the bar men in the East-end of London would take their buckets down to the Thames to collect oysters to put on the bar free for those who bought beer.

So to what extent has pollution of the rivers, estuaries, bays and coast lines destroyed CO2 sinks such as would have started the estuarine food web and provided food for the oysters mussels etc.

In my life time the Firth of Forth has gone from a rich sea-food resource to an array of Department of Environment notices warning mussels unfit for human consumption.

Should we start a campaign to retore the estuaries and extend mussel, scallop, clam and oyster farms to the benefit of all?


The media headlines about “Acid Oceans” don’t really help. Casual readers might be jumping to the conclusion that in a few years time, taking a dip in the sea will turn any unwary bather into a fizzing, steaming pile of skeletal remains, should there not be an urgent total ban on CO2. “Possibility of Slightly Less Alkaline Oceans” doesn’t have quite the same shock value, however.

Geoff – surely you mean ‘interaction’ but thanks for the (implied) vote of confidence.

I read many of the key blogs most days but have trained myself to count to 100 before commenting now. This blog is good because Maurizio brings many new things and perspectives to the table (and it has a brilliant name).

There was an interesting set of threads on a few days ago (and over several days) by a guest blogger and also Cory Doctorow (in the AGW camp). Just reading the replies of some smart people (who in many cases know so little) brings home just how messy this whole ‘debate’ is going to get. Worth a read if you have time.

Thank you “Luke” for your kind words. As a matter of fact one of the main points of this blog is indeed to “bring many new things and perspectives to the table”. I try to stay away from arguments well beaten by the likes of McIntyre, Watts, Lubos and Lucia.

If I do not have anything truly new to say, I usually do stay quiet…if anybody can believe that!! 😎

You deserve some kind of Green Nobel Prize, if only for having provoked Luke Warmer’s intervention. Have I got this right? Dozens of island nations perched perilously above acid-ocean-threatened coral atolls are in danger, because of our failure to sufficiently deplete stocks of carbon-emitting fish? Eat more cod, and save the Maldives? I’m with you all the way.

With all due respect to the theoretical speculations of scientists looking into this matter, has anyone gone down the relatively cost effective route (surely a job that could be assigned to a PHD student) of doing a survey of people who grow coral for commercial gain (i.e., sales to petshops, etc.) to determine what ph they’ve found optimum?

If the answer is known, what is it?

If the answer is not known, why isn’t it known?


Glad to see you’re back on the case and nice analysis of the figures. I think you have to remember the warmist dogma “it’s different now” meaning that man-made CO2 is nastier than naturally-made “organic, free-range” CO2.

I’ve also been doing some digging on matters oceanic after the scare stories about fish-produced calcium carbonate (gut rocks) which had got me wondering about how much Co2 fish exhale and many other things.

The facts from the Press Release were:
“This study estimates that three to 15 per cent of marine calcium carbonate is in fact produced by fish in their intestines and then excreted.
This is a conservative estimate and the team believes it has the potential to be three times higher.
Fish are therefore responsible for contributing a major but previously unrecognised portion of the inorganic carbon that maintains the ocean’s acidity balance. The researchers predict that future increases in sea
temperature and rising CO2 will cause fish to produce even more calcium carbonate.”

and goes on to say

“And what about the future? The researchers predict that the combination of increases in sea temperature and rising CO2 expected over this century will cause fish to produce even more calcium carbonate. This is for two reasons. Firstly, higher temperatures stimulate overall metabolism in fish, which drives all their biological processes to run faster. Secondly, increasing CO2 in their blood directly stimulates carbonate
production by the gut specifically.”

I get very suspicious when thermal impacts of climate change are invoked – you know, warmer waters leading to hotter fish. I’m also confused as higher pCO2 leading to (allegedly) warmer temperatures should lead to lower CO2 solubility. Curiously there was no mention of depletion of fish stocks which would I’m sure have been the trope if there wasn’t a more glamorous/lucrative one. (but alerting us to the threat of alkaline oceans)

Even ignoring the complex macro-ocean issues of the various oscillations (ENSO etc), it is clear that very little is known about the oceans as the press release concludes:

“We have really only just scratched the surface of knowing the chemistry and fate of fish carbonates. Given current concerns about the acidification of our seas through global CO2 emissions, it is more important than ever that we understand how the pH balance of the sea is normally maintained.”

I got a few papers and even a thesis on this but sadly, real life/work intervened. One thing is clear is that there is a news climate amplification route – journo’s always pad the science press release to invoke an alarmist climate change headline but sincethe press release itself is also padded to invoke climate change there is much distortion.

The warmers who constantly cite peer review as the only criteria for truth are sadly deluded. From my own experience I know that the fee paid for reviewing a PhD is peanuts, relative to the time required, and a paper in a journal, well diddly squat.

Rant over. Keep up the good work

Omni is the year 2000 value in graph [iii] based on real observation ?

The dot between 1800 and 2000 would correspond with …?

Turley et al (2006) sites Riebesell, U. et al. Reduced calcification of marine plankton in response to increased atmospheric CO2 . Nature 407, 364–-367 (2000).

Instead of the newer Riebesell (2004) Responses of Marine Phytoplankton to Elevated Atmospheric CO2

Riebesell presents a preview of some as-yet-unpublished [ probably published by now – Jim] results of CO2 perturbation experiments conducted south of Bergen, Norway, where nine 11-m3 enclosures moored to a floating raft were aerated in triplicate with CO2-depleted, normal, and CO2-enriched air to achieve CO2 levels of 190, 370 and 710 ppm, simulating glacial, present day, and predicted conditions for the end of the century, respectively. In the course of the study, a bloom consisting of a mixed phytoplankton community developed; and, in Riebesell’s words, “significantly higher net community production was observed under elevated CO2 levels during the build-up of the bloom.” He further reports that “CO2-related differences in primary production continued after nutrient exhaustion, leading to higher production of transparent exopolymer particles under high CO2 conditions,” something that has also been observed by Engel (2002) in a natural plankton assemblage and by Heemann (2002) in monospecific cultures of both diatoms and coccolithophores. These particles, according to Riebesell, “accelerate particle aggregation and thereby enhance vertical particle flux,” which he says may “provide an efficient pathway to channel dissolved and colloidal organic matter into the particulate pool.”

This colloidal organic matter is magic stuff. It acts like a sponge sopping up nutrients and keeping them suspended near the surface so that planktons can get the stuff they need to grow at their leasure. Sort of a pantry for plankton.

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