Robert Grumbine has explored the unreliability of a particular source in several of his posts, and I thought I’d comment on a similar experience with the same group, “Climate Realists (formerly CO2 Skeptics)”. Looking for media coverage of the InterAcademy Panel’s statement on ocean acidification (more on that later), I came across this post by Craig Idso, entintled- I kid you not- “The Ocean Acidification Fiction”.
Idso is a favorite of the denialists, as unlinke the vast majority (e.g. the gruesome twosome of Monckton and Inhofe) he has a science background (and ostensibly some relevant publications), and can at least mantain a veneer of sanity. This by no means makes him or “Climate Realists” a reliable source on climate change and associated issues however, as the post in question reveals in short order.
Idso cites Liu et al.’s Instability of seawater pH in the South China Sea during the mid-late Holocene: Evidence from boron isotopic composition of corals as the first supporting study for his claim that ocean acidification is “fiction”.
Idso [emphasis mine]:
Working with eighteen samples of fossil and modern Porites corals recovered from the South China Sea, the nine researchers employed 14C dating using the liquid scintillation counting method, along with positive thermal ionization mass spectrometry to generate high precision δ11B (boron) data, from which they reconstructed the paleo-pH record of the past 7000 years that is depicted in the figure below.
As can be seen from this figure, there is nothing unusual, unnatural or unprecedented about the two most recent pH values. They are neither the lowest of the record, nor is the decline rate that led to them the greatest of the record. Hence, there is no compelling reason to believe they were influenced in any way by the nearly 40% increase in the air’s CO2 concentration that has occurred to date over the course of the Industrial Revolution. As for the prior portion of the record, Liu et al. note that there is also “no correlation between the atmospheric CO2 concentration record from Antarctica ice cores and δ11B-reconstructed paleo-pH over the mid-late Holocene up to the Industrial Revolution.”
But as Liu et al. explicitly state in their abstract [emphasis mine]:
The paleo-pH records of the SCS, reconstructed from the δ11B data, were not stable as previously thought but show a gradual increase from the Holocene thermal optimal and a sharp decrease to modern values. The latter is likely caused by the large amount of anthropogenic CO2 emissions since the Industrial Revolution but variations of atmospheric pCO2 cannot explain the pH change of the SCS before the Industrial Revolution. We suggest that variations of monsoon intensity during the mid-late Holocene may have driven the sea surface pH increase from the mid to late Holocene. Results of this study indicate that the impact of anthropogenic atmospheric CO2 emissions may have reversed the natural pH trend in the SCS since the mid-Holocene. Such ocean pH records in the current interglacial period can help us better understand the physical and biological controls on ocean pH and possibly predict the long-term impact of climate change on future ocean acidification.
This is a beautiful example of the classic denialist tactic of citing studies that explicitly refute your argument as though they support it. As the utter dearth of refereed studies supporting denialists’ claims became ever more apparent (highlighted memorably by Naomi Oreskes’ metanalysis of the consensus view in Science), they had little choice but to pretend the opposite. Hence the Heartland Institute claiming Michael Mann and others’ published work “Contradicts Man-Made Global Warming Scares” when it consists of years and even decades of supporting it.
Idso then cites Pelejero et al.’s Preindustrial to Modern Interdecadal Variability in Coral Reef pH as further support that ocean acidificaiton is “fiction”. However, Pelejaro et al. open [emphasis mine]:
The oceans are becoming more acidic due to absorption of anthropogenic carbon dioxide from the atmosphere. The impact of ocean acidification on marine ecosystems is unclear, but it will likely depend on species adaptability and the rate of change of seawater pH relative to its natural variability. To constrain the natural variability in reef-water pH, we measured boron isotopic compositions in a È300-year-old massive Porites coral from the southwestern Pacific. Large variations in pH are found over È50-year cycles that covary with the Interdecadal Pacific Oscillation of ocean-atmosphere anomalies, suggesting that natural pH cycles can modulate the impact of ocean acidification on coral reef ecosystems.
Since the beginning of the industrial revolution, the burning of fossil fuels has increased the CO2 content of the atmosphere from È280 to more than 370 parts per million per volume (ppmv), a level unprecedented in the last 420,000 years (1). To date, a large part of anthropogenic CO2 emissions has been absorbed by the oceans (2), which have become more acidic, thus reducing their capacity to continue to absorb CO2. Estimates of global oceanic pH trends to the year 2000 indicate that the oceans have already acidified by 0.1 pH units relative to preindustrial times (3, 4). Geochemical models forecast an exponential decrease of nearly 0.8 pH units by 2300 (4), a scenario for which there is no obvious precedent over the last hundreds of millions of years (5), with the possible exception of abrupt changes such as those associated with the Paleocene/Eocene Thermal Maximum 55.5 million years ago (6).
Although Pelejaro et al. quite explicitly contradict Idso’s broader assertion (that acidification is a “fiction”), what Idso/Climate Realists is attempting here is better viewed as a different tactic than that used with Liu et al., another favorite of denialists- the cherry pick.
If a study cited by a denialist doesn’t outright refute what he claims it supports, it will almost assuredly consist of a study that deals with an isolated instance or location and concern itself with phenomena that have nothing to do with or in no way obviate the broad effects of climate change (or as here ocean acidification).
Idso cites the lack of a statistically significant decline decline in pH in addition to the large amount of variability experienced by Flinders reef as though it somehow invalidates ocean acidification:
These researchers also found that “there is no notable trend toward lower δ11B values.” Instead, they discovered that “the dominant feature of the coral δ11B record is a clear interdecadal oscillation of pH, with δ11B values ranging between 23 and 25 per mil (7.9 and 8.2 pH units),” which they say “is synchronous with the Interdecadal Pacific Oscillation.”
Pelejaro et al. explain the likely cause of the variability:
The most likely explanation for the variability in pH at Flinders Reef is that coral reef calcification combined with limited flushing of reef water exerts an important local control over the extent of the buildup of partial pressure of CO2 (PCO2) within the reef…
And discuss their findings in context of the acidifying ocean:
The interdecadal cycle in seawater pH observed at Flinders Reef has relevance for predicting its response to future ocean acidification, given that it will either enhance or moderate the local effects of the projected long-term decrease in pH (3, 4). For example, the next rise in the ~50-year cycle of reef-water pH should counteract the lowering of pH values at Flinders Reef until ~2035 A.D. Conversely, the subsequent fall in the reef-water pH cycle will lead to an abrupt shift toward low pH reef water. The extent to which corals and other calcifying reef organisms can adapt to such rapid decreases in pH is largely unknown.
Our findings suggest that the effects of progressive acidification of the oceans are likely to differ between coral reefs because reef-water PCO2 and consequent changes in seawater pH will rarely be in equilibrium with the atmosphere. Although the relatively large variations in seawater pH at Flinders Reef suggest that coral reefs may be resilient to the shorter term effects of ocean acidification, in the coming decades many reefs are likely to experience reduced pH that is unprecedented relative to “natural” levels. Additional paleo-pH records are required from a range of coral reef ecosystems to improve our understanding of the physical and biological controls on reef-water pH, and the long-term impacts of future ocean acidification.
Note that Pelejaro et al. explicitly are not claiming that the natural variability in pH that Flinders reef experienced due to its particular geographic circumstances is evidence that Flinders will be immune to the negative consequences of acidification on longer timescales, and in no way refute (and as we’ve seen extensively reference) the reality of acidification generally. Indeed, they repeatedly state that Flinders reef’s local geography cannot be compared to open ocean for purposes of discussing pH and dissolved CO2 in response to comments about the implausibility of their findings.
Idso proceeds to cite, if you can believe the chutzpah, Evidence for ocean acidification in the Great Barrier Reef of Australia. The abstract [emphasis mine]:
Geochemical records preserved in the long-lived carbonate skeleton of corals provide one of the few means to reconstruct changes in seawater pH since the commencement of the industrial era. This information is important in not only determining the response of the surface oceans to ocean acidification from enhanced uptake of CO2, but also to better understand the effects of ocean acidification on carbonate secreting organisms such as corals, whose ability to calcify is highly pH dependent. Here we report an 200 year δ11B isotopic record, extracted from a long-lived Porites coral from the central Great Barrier Reef of Australia. This record covering the period from 1800 to 2004 was sampled at yearly increments from 1940 to the present and 5-year increments prior to 1940. The δ11B isotopic compositions reflect variations in seawater pH, and the δ13C changes in the carbon composition of surface water due to fossil fuel burning over this period. In addition complementary Ba/Ca, δ18O and Mg/Ca data was obtained providing proxies for terrestrial runoff, salinity and temperature changes over the past 200 years in this region. Positive thermal ionization mass spectrometry (PTIMS) method was utilized in order to enable the highest precision and most accurate measurements of δ11B values. The internal precision and reproducibility for δ11B of our measurements are better than ±0.2‰ (2σ), which translates to a precision of better than ±0.02 pH units. Our results indicate that the long-term pre-industrial variation of seawater pH in this region is partially related to the decadal–interdecadal variability of atmospheric and oceanic anomalies in the Pacific. In the periods around 1940 and 1998 there are also rapid oscillations in δ11B compositions equivalent changes in pH of almost 0.5 U. The 1998 oscillation is co-incident with a major coral bleaching event indicating the sensitivity of skeletal δ11B compositions to loss of zooxanthellate symbionts. Importantly, from the 1940s to the present-day, there is a general overall trend of ocean acidification with pH decreasing by about 0.2–0.3 U, the range being dependent on the value assumed for the fractionation factor α(B3–B4) of the boric acid and borate species in seawater. Correlations of δ11B with δ13C during this interval indicate that the increasing trend towards ocean acidification over the past 60 years in this region is the result of enhanced dissolution of CO2 in surface waters from the rapidly increasing levels of atmospheric CO2, mainly from fossil fuel burning. This suggests that the increased levels of anthropogenic CO2 in atmosphere has already caused a significant trend towards acidification in the oceans during the past decades.
Idso finishes [notation mine]:
In light of these several diverse and independent assessments of the two major aspects of the ocean acidification hypothesis —  a CO2-induced decline in oceanic pH that  leads to a concomitant decrease in coral growth rate — it would appear that the catastrophe conjured up by the world’s climate alarmists is but a wonderful work of fiction.
On the first point, not one of the studies Idso cites backs his claim that this is not occurring, and in fact they all explictly refute him. Indeed the general decline in ocean pH due to anthropogenic CO2 emissions is a robust finding, apparently unchallenged in the primary literature.
On the second point, Idso appears to be passing off the Pelejaro et al. paper, which explicitly rejects the claim that longterm acidification will have no effect on the corals studied, as a complete rebuttal to the threat of acidfication to corals and coral growth. Idso also necessarily ignores the numerous papers published testing and confirming the “alarmist” view that he claims is unsubstantiated, e.g. Hoegh-Guldberg et al. Coral Reefs Under Rapid Climate Change and Ocean Acidification, 2007; Guionette and Fabry Ocean acidification and its potential effects on marine ecosystems, 2008; Jokiel et al. Ocean acidification and calcifying reef organisms: a mesocosm investigation, 2008; Anthony et al. Ocean acidification causes bleaching and productivity loss in coral reef builders, 2008; Doney et al. Ocean Acidification: The Other CO2 Problem, 2009; Silverman et al. Coral reefs may start dissolving when atmospheric CO2 doubles, 2009; etc.
Bottom line: Climate Realists [aka CO2 Skeptics] and Craig Idso are an unreliable source engaging in deliberate falsehoods designed to mislead readers. Whenever possible, and especially when dealing with claims that are far outside the mainstream, check references and read primary sources. Denialists have no qualms about misrepresenting papers or even citing studies that directly refute their claims.