Ocean Acidification: Natural Cycles and Ubiquitous Uncertainties

Guest essay by Jim Steele,

Director emeritus Sierra Nevada Field Campus, San Francisco State University and author of Landscapes & Cycles: An Environmentalist’s Journey to Climate Skepticism

In 2002, Scripps’ esteemed oceanographer Walter Munk argued for the establishment of an Ocean Observation System reporting, “much of the twentieth century could be called a “century of undersampling” in which “physical charts of temperature, salinity, nutrients, and currents were so unrealistic that they could not possibly have been of any use to the biologists. Similarly, scientists could find experimental support for their favorite theory no matter what the theory they claimed. ” Due to that undersampling MIT’s oceanographer Carl Wunsch (2006) likewise noted, “Among the more troublesome distortions now widely accepted, one must include the notion that the ocean circulation is a simple “conveyor belt” and that the Gulf Stream is in danger of ‘turning off’.”

Another such favorite theory, mistakenly offered as a fact, speculates we are now witnessing increasing anthropogenic ocean acidification, despite never determining if current pH trends lie within the bounds of natural variability. Claims of acidification are based on an “accepted scientific paradigm” that “anthropogenic CO2 is entering the ocean as a passive thermodynamic response to rising atmospheric CO2.” Granted when all else is equal, higher atmospheric CO2 concentrations result in more CO2 entering the oceans and declining pH. But the ever-changing conditions of surface waters exert far more powerful effects. Whether we examine seasonal, multi-decadal, millennial or glacial/interglacial time frames, ocean surfaces are rarely in equilibrium with atmospheric CO2. Relative to atmospheric CO2, seasonal surface water can range up to 60% oversaturated due to rising acidic deep water. Due to the biological pump, CO2 concentrations can be drawn down, leaving surface waters as much as 60% under‑saturated (Takahashi 2002). Thus we cannot simply attribute trends in surface water pH to equilibration with atmospheric CO2. We must first fully account for natural ocean cycles that raise acidic waters from deeper layers and the biological responses that pump CO2 back to ocean depths.

[note: in this essay I use “acidic” in a relative sense. For example, although the pH of ocean water is 7.8 at 250 meters depth and is technically alkaline, those waters are “more acidic” relative to the surface pH of 8.1.]

To appreciate the importance of pH altering dynamics, consider the fact that pure water has a neutral pH of 7.0. Rainfall quickly equilibrates with atmospheric CO2, and pH falls to ~5.5. Dark‑water rivers such as the Rio Negro drop to pH 5.1. In contrast, due to a combination of biological activities and geochemical buffering, the average pH of ocean surfaces (and some rivers) rises to ~8.1. In other words, after equilibration with atmospheric CO2, powerful factors combine to remove 99.8% of all acidifying hydrogen ions from rainwater. The balance between upwelled acidic waters versus carbon sequestration and export by the “biological pump” is the key factor maintaining high pH in oceanic surface waters, and the communities of plankton that operate that pump undergo changes on seasonal, multidecadal and millennial time scales; changes we are just beginning to understand.

In Bates 2014, A Time-Series View of Changing Surface Ocean Chemistry Due to Ocean Uptake of Anthropogenic CO2 and Ocean Acidification, they simplistically argued declining ocean pH is “consistent with rising atmospheric CO2. But a closer examination of each site used in their synthesis suggests their anthropogenic attribution is likely misplaced. For example, at the Hawaiian oceanic station known as HOT, based on 10 samplings a year since 1988, researchers reported a declining pH trend. But that trend was not consistent with invasions from atmospheric CO2. An earlier paper (Dore 2009) had observed, “Air-sea CO2 fluxes, while variable, did not appear to exert an influence on surface pH variability. For example, low fluxes of CO2 into the sea from 1998–2002 corresponded with low pH and relatively high fluxes during 2003–2005 were coincident with high pH; the opposite pattern would be expected if variability in the atmospheric CO2 invasion was the primary driver of anomalous DIC accumulation. (DIC is the abbreviation for Dissolved Inorganic Carbon referring to the combined components derived from aqueous CO2, including bicarbonate and carbonate ions.)

Those higher fluxes of CO2 into the surface likely stimulated a more efficient biological pump resulting in higher pH. That rise in pH is consistent with experimental evidence demonstrating CO2 is often a limiting nutrient (Riebesell 2007), and adding CO2 stimulates photosynthesis. That most photosynthesizing plankton have CO2 concentrating mechanisms suggests CO2 is often in chronic short supply.

The greatest concentrations of CO2 upwell from depth to invade surface waters. As seen below in the illustration by Byrne 2010 from the northern Pacific, the ocean’s pH (thus the store of DIC) rapidly drops from 8.1 at the surface to 7.3 at 1000 meters depth. Dynamics such as upwelling bring deeper waters to the surface reducing pH, while dynamics such as the biological pump shunt carbon back to deeper depths and raise surface pH. At the risk of oversimplifying a myriad of complex dynamics, oceans basically undergo a 4-phase cycle that determines the average annual surface pH. Any adjustments to this cycle will alter trends in pH over decadal to millennial time periods.

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Phase 1: Varied rates of upwelling and winter mixing raises acidic water to the sunlit surface and

lowers pH.

Phase 2: Specific plankton communities, largely diatoms respond quickly to the arrival of

nutrients in the surface waters, and rapidly sequester and export carbon back to depth. Phase-2 productivity also generates dissolved and suspended organic carbon that is transported laterally to other regions. When community photosynthesis absorbs CO2 faster than respiration releases it or upwelling injects it, surface pH rises.

Phase 3: As available nutrients are depleted, diatom populations dwindle and other plankton

communities dominate such as coccolithophores and photosynthesizing bacteria. Instead of rapidly exporting carbon, this plankton community is better at retaining and utilizing nutrients. The utilization of suspended and dissolved organic carbon and increased grazing by populations of zooplankton increase respiration rates relative to new photosynthesis, so pH declines.

Phase 4: A “regional equilibrium” is established as accumulated organic carbon from previous

phases is depleted and new, but lower, levels of productivity are balanced by community respiration. That balance raises pH. This equilibrium is fleeting and lasts until a new burst of nutrients reaches sunlit waters. The supply of nutrients rising to the surface cycles seasonally as well as over decades, millennia and glacial/interglacial intervals, so that short interval trends are embedded in much longer trends. This is one reason why computed pH trends by Bates 2014 statistically explained only a minor portion of pH variability even after removing seasonal trends.

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First consider that oceans store 50 times more CO2 than the atmosphere. A small change in the rate by which deep acidic water reaches the surface is the major determinant of surface pH trends. Nutrients, acidity, and density increase with depth, but not all depths contain a balanced supply of nutrients critical for photosynthesis. To bring denser water to the surface requires a significant input of energy that is primarily provided by the winds or tides (Wunsch 2004). Stronger winds generate more upwelling and winter mixing. Thus cycles of oceanic and atmospheric circulation that strength and weaken winds, raise varied combinations and concentrations of nutrients to the surface, which accordingly affects the biological pump and pH.

For example in temperate oceans, winter cooling of surface waters allows winds and storms to mix surface waters with CO2 rich waters from as deep as 500 meters. This lowers surface pH, so that relatively insignificant inputs from atmospheric CO2 are undetectable. (Takahashi 2002, 1993). Several researchers have observed significant correlations between winter mixing and the North Atlantic Oscillation (Ullman 2009, Steinberg 2012). A positive NAO is associated with stronger westerly winds and also correlates with a stronger subpolar gyre. Counter-clockwise gyres in the northern hemisphere increase regional upwelling when they strengthen. So changes in NAO-driven upwelling cause multi-decadal oscillations in the plankton communities and pH.

In the Pacific, El Nino years strengthen the Aleutian Low and the Pacific subpolar gyre, similarly increasing regional upwelling. In contrast during La Nina years, gyre upwelling decreases but trade winds speed up and intensify coastal and equatorial upwelling. The frequency of El Niño’s vs La Niña’s varies over 40 to 60 year cycles of the Pacific Decadal Oscillation. Although periods of increased upwelling decreases pH, due to undersampling it is not clear how this extrapolates across the whole Pacific Basin during the 20th century.

Upwelling also varies on millennial scales. During the Roman Warm Period, Medieval Warm Period and the Current Warm Period, La Nina-like conditions with stronger trade winds dominated (Salvatteci 2014) causing above average upwelling and higher productivity. During cooler periods like the Dark Ages and Little Ice Age, the Pacific was dominated by El Nino-like conditions with less upwelling and lower productivity. Claims that oceans have acidified since the Little Ice Age due to anthropogenic CO2 (Caldeira 2003) may be true, but the uncertainties are huge. It is just as likely increased upwelling caused more acidic modern oceans, or it is equally possible that modern oceans are less acidic if increased upwelling stimulated a biological pump that sequestered and exported enough carbon to offset acidic upwelling.

Global ocean acidification is determined by averaging sink regions with out‑gassing source regions. Opposing regional trends add significant uncertainty when determining global calculations. As illustrated by the yellows and reds in the Martinez-Boti (2015) illustration below, there are vast regions where so much DIC is upwelled, on average the ocean is exhaling CO2. Regions that are net sources of out-gassing CO2 experience lower pH solely due to upwelling of ancient waters, and the pH is lower than predicted from simple equilibration with the atmosphere.

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Paradoxically, oceans also experience acidification if weakening winds reduce upwelling. For example due to changing locations and strength of the InterTropical Convergence Zone (ITCZ), trade winds over northern Venezuela’s Cariaco Basin undergo decadal and centennial shifts in strength. When the ITCZ moved south during the Little Ice Age, upwelling and productivity in the Cariaco Basin declined. At the end of the LIA, the ITCZ began moving northward and upwelling and productivity increased (Gutierrez 2009). Recently the ITCZ moved further northward due to more La Niña’s and the negative Pacific Decadal Oscillation, and regional winds declined. Consequently researchers reported anomalously shallow seasonal upwelling that brought more DIC to the surface but fewer critical nutrients that reside at lower depths. This resulted in decreased productivity and a decrease in diatom populations. Less productivity and less carbon export did not offset upwelled DIC, so the regional pH declined (Astor 2013). Despite Astor serving as a co-author, Bates 2014 oddly failed to mention this pH altering dynamic, choosing to attribute Cariaco’s declining pH trend to rising anthropogenic CO2.

In contrast to the Cariaco Basin, a negative Pacific Decadal Oscillation increases upwelling along the Americas west coast, stimulating the highly productive/high carbon-export community of phase-2. Upwelled DIC is quickly sequestered and exported by large single-celled diatoms. With their relatively heavy siliceous shells, dead diatoms rapidly sink carrying carbon to the sea floor. Larger zooplankton graze on diatoms and their large fecal pellets and carcasses also carry carbon rapidly to depth. Diatom blooms along California and Oregon spark increased krill and anchovy populations, which attract feeding humpback whales from Costa Rica and seabirds like the Sooty Shearwater from New Zealand, confounding any attempts accurately measure the carbon budget.

As illustrated in the Evans et al graph below, coastal upwelling can over‑saturate the surface waters to 1000 matm, 2.5 times above atmospheric pCO2 (represented by dashed horizontal line). Within weeks the biological response sequesters and exports that carbon so that concentrations of surface water CO2 fall as low as 200 matm; a concentration that would still be under-saturated relative to the Little Ice Age’s atmosphere. Relative to these rapid seasonal changes in pH, fears that marine organisms cannot adapt quickly enough to the relatively slower changes wrought by anthropogenic CO2 seem overblown.

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Still such fears filter researchers’ interpretations. Along the west coast of North America, planktonic sea snails called pteropods, begin life feeding on algal blooms ignited by seasonal coastal upwelling. As illustrated in scanning electron micrograph “a”, shown below from (Bednarsek 2014), pteropod shells are heavily dissolved during the first few weeks of life due to acidic upwelled water. Picture “b” shows a larger more mature shell with the outer part of the shell experiencing no dissolution. As the snails matured, either upwelled acidic waters subsided or the snail was transported seaward to less acidic waters by the same currents that promoted upwelling. The result is pteropod shell dissolution is a very localized, short duration phenomenon.

Nonetheless in a study sponsored by NOAA’s Ocean Acidification Program Bednarsek 2014 argued those examples of shell dissolution were caused by anthropogenic carbon writing, “We estimate that the incidence of severe pteropod shell dissolution owing to anthropogenic OA has doubled in near shore habitats since pre-industrial conditions across this region and is on track to triple by 2050.” But such “conclusions” are unsupported speculation at best. The study failed to determine if upwelled waters were any more acidic now than during any other seasonal or La Nina upwelling event. Most studies suggest upwelling declined during the Little Ice Age, and the resumption of stronger upwelling is the result of a natural cycle. But Bednarsek (2014) simply used a formula equilibrating past and present atmospheric CO2 to compute surface water pH. But such methodology is meaningless. No net CO2 diffusion from the atmosphere to surface waters occurs when upwelling has oversaturated surface pCO2, and as shown in the Evans et al graph, due to the biological pump surface waters remained undersaturated relative to both current and LIA atmospheric CO2. Shame on those NOAA scientists for such biased interpretations.

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On all time frames, when upwelling subsides and nutrients and carbon become scarce, diatom populations dwindle and oceans transition to Phase 3. Coccolithophore and bacterial communities that were relatively minor constituents, begin to dominate. Smaller bacteria remain suspended in the surface layers and export much less carbon. Grazing on increasingly abundant bacteria and accumulated organic carbon, promotes greater zooplankton populations. As a result, community respiration rates increase, and higher CO2 concentrations lower surface pH.

clip_image012Coccolithophores are large single-celled alga encased by several ornate calcium-carbonate “coccoliths”, so that sinking dead individuals do export carbon relatively quickly. However the construction of coccoliths metabolically increases surface pCO2, lowers pH and counteracts the “biological pump”. When calcium combines with carbonate ions to form coccoliths, the reaction releases acidifying CO2. Likewise the growth of pteropods’ calcium carbonate shells also increases CO2. It seems paradoxical that one of the greatest fears of ocean acidification is the dissolution of carbonate shells, yet the very process of creating those shells increases acidification and lowers surface alkalinity.

Several researchers suggest coccolith formation evolved to provide much needed CO2 for photosynthesis in under-saturated waters. Experimental evidence reveals higher concentrations of CO2 results in lower rates of coccolith formation but proponents of worrisome acidification argue this is evidence of acidification’s deleterious effects. However the same response would be expected if the rate of coccolith formation responds to the available supply of CO2 required for photosynthesis. Furthermore if they are so vulnerable to acidification, how did coccolithophores evolve and survive over 200 million years ago, when atmospheric CO2 was at least 2 to 3 times higher than today?

Without copious supplies of nutrients from upwelling, productivity in subtropical gyres is much lower and diatoms constitute a minor component of that plankton community. But they still undergo cyclic changes. In the Atlantic, Steinberg (2012) describes a 113% decrease in diatoms between 1990 and 2007 in contrast to stable coccolithophore populations and a rapidly increasing community of photosynthesizing bacteria. In turn rapidly increasing communities of small zooplankton graze on the bacteria resulting in increased community respiration rates. Three sites from Bates 2014 are located in subtropical gyres: HOT near Hawaii, BATS near the Bermuda and ESTOC near the Canary Islands. And all three are exhibiting these classic phase-3 patterns with increasing respiration rates (Lomas 2010, Gonzalez-Davila 2003, Peligri 2005, Steinberg 2012), which accounts for declining pH trends. As shown by Steinberg 2012, those trends are significantly correlated with multi-decadal climate indices – the North Atlantic Oscillation plus three different Pacific Ocean climate indices”.

Global pH decreased when oceans transitioned from the Last Glacial Maximum (LGM) to the current interglacial Teleconnections between the Atlantic and Pacific have been confirmed as warm periods in the Greenland ice core correlate with periods of extended periods of upwelling along the California coast (Ortiz 2005). Recent research also links simultaneous multi‑millennial cycles of upwelling and higher productivity in the sub‑Antarctic Atlantic and equatorial Pacific. Most research suggests that at the end of the LGM, Antarctic began to warm followed by a rise in atmospheric CO2. Although the precise mechanism of CO2 out‑gassing during the deglacial period has been under debate, there is a growing consensus that circulation changes caused aged waters rich in nutrients to upwell in subpolar Antarctic waters. Via oceanic tunneling, those deep Antarctic waters also upwelled in the equatorial eastern Pacific. Using foraminifera proxy data, the graphic below from Martinez-Boti (2015) shows periodic upwelling of subpolar Antarctic waters (on the left in blue) caused regional pH to decline from the LGM maximum of 8.4 to about 8.1 at the beginning of the Holocene. Due to the biological pump and/or reduced upwelling during the early and mid Holocene, pH rises and bounces between 8.25 and 8.15.

Based on CO2 concentrations determined from Antarctic ice cores, Martinez‑Boti also constructed a green “Equilibrium pH” trend indicating the surface pH if it had simply equilibrated with atmospheric CO2. For most of the past 20,000 years, surface waters were not in atmospheric equilibrium and more acidic, so those regional oceans were typically a source of out‑gassing CO2. The graphs on the right (in red) show the same pattern for the equatorial eastern Pacific but with data that extends further into the LGM.

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Calvo 2011 examined ocean sediments to determine the strength of upwelling versus the biological pump plus the relationship between diatoms and coccolithophores over the past 40,000 years. Their research found lower productivity during the LGM and lower diatom abundance relative to coccolithopheres. As upwelling increased around 20,000 years ago so did ocean productivity and the proportion of diatoms. They concluded upwelling enhanced the biological pump but it was “not sufficient to counteract the return to the atmosphere of large amounts of CO2 delivered by the oceans through an enhanced ventilation of deep water.”

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Finally examining sediments in the eastern equatorial Pacific, Carbacos 2014 found “a clear prevalence of dominant La Niña-like conditions during the early Holocene, with an intense upwelling and high primary productivity.” High levels of productivity persisted through the Holocene Optimum until productivity dramatically declined around 5,500 years ago. Since that time Carbacos 2014 reports, “An alternation between El Niño-like and La Niña-like dominant conditions occurred during the late Holocene, characterized by a clear trend toward prevailing El Niño-like conditions, with a low primary productivity.” During the past 5,000 years, that lower productivity coincided with increased dominance of coccolithophores and declining proportions of diatoms. That suggests the oceans have been in a phase-3 multi-millennial decline in pH superimposed on multidecadal cycles driven by the Pacific Decadal and Atlantic Multidecadal Oscillations.

It is also worth noting, as seen in the graph below, throughout the Holocene changes in atmospheric CO2 did not correlate with temperature. However atmospheric CO2 did track changing plankton communities. During the early and late Holocene, atmospheric CO2 concentrations were relatively low and stable during periods of high productivity with higher ratios of diatoms. When ocean productivity crashed overall around 5,000 years ago, the proportion of CO2 producing coccolithophores increased and atmospheric CO2 likewise increased by about 20 matm. A similar annual increase in CO2 has been observed in modern oceans and similarly attributed to increased proportions of coccolithophores (Bates 1996).

So where are the oceans headed? If history repeats itself, declining solar insolation will result in less upwelling, lower productivity, a reduced biological pump and higher pH. Or perhaps higher levels of atmospheric CO2 will increase productivity as observed in several experiments, or perhaps rising CO2 will cause a deleterious decline in pH? The ubiquitous uncertainties from the current undersampling of oceans allows anyone to “find experimental support for their favorite theory no matter what the theory they claimed.” But I can say for sure, I would not trust any predictions that failed to account for changes in upwelling and the various responses of the biological pump.

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160 thoughts on “Ocean Acidification: Natural Cycles and Ubiquitous Uncertainties

    • From the above link:

      Problem

      Our ocean is currently in the midst of a silent crisis. Rising levels of atmospheric carbon are resulting in higher levels of acidity. The potential biological, ecological, biogeochemical and societal implications are staggering. The absorption of human CO2 emissions is already having a profound impact on ocean chemistry, impacting the health of shellfish, fisheries, coral reefs, other ecosystems and our very survival.

      So, there is apparently no good data to make such a “staggering” claim.

      Then immediately below the above declaration on the same page (emboldened mine):

      The Market Failure

      While ocean acidification is well documented in a few temperate ocean waters, little is known in high latitudes, coastal areas and the deep sea, and most current pH sensor technologies are too costly, imprecise, or unstable to allow for sufficient knowledge on the state of ocean acidification.

      So, um…our “VERY SURVIVAL” is drawn from what exactly?

      • “Rising levels of atmospheric carbon are resulting in higher levels of acidity.” Atmospheric carbon? They make it sound like the sky is turning black with soot.

      • It is drawn from the need for jobs for climate researchers. Theorize a potential crisis, and someone will buy it. Unfortunately it is the government that is buying it, due to the green energy lobby, and us taxpayer are footing the bill, and getting screwed by energy policy to boot!

    • Just pour a few hundred million gallons of sulfonephthalein into the ocean and voila the ocean is self pH indicating.

  1. Mr. Steele,
    Great information provided as usual.
    If I understand what you’ve said correctly – the ability of ocean’s to process CO2 is actually a biological one. Existing processes already are limited by the availability of CO2, thus any significant pH changes (i.e. acidification) would require demonstration that there are some biological limits in oceanic flora/fauna to process CO2 rather than the amount of CO2 in the atmosphere.
    Or in simpler terms – if the CO2 consuming flora/fauna of the oceans are already growing until accessible CO2 levels are too low for further expansion, then addition of CO2 should have no effect whatsoever on acidification unless there is some hard physical expansion limit.

    • With atmospheric CO2 levels of several thousand PPM during the Devonian. Silurian, Ordovician and Cambrian one wonders why the abundant shelled mollusks and corals (preserved as fossils) that existed during those two hundred million years didn’t simply dissolve?

      • The historic CO2 information seems consistent with what I believe Mr. Steele is saying: atmospheric CO2 levels are a relatively minor factor compared with biomass impact with regards to CO2 levels in the ocean.
        Surface CO2 absorption is mostly consumed by biological organisms – these organisms then sequester carbon in non-CO2 form into the deep ocean as they die, or into the rest of the ocean biosphere as they pass up the food chain.

    • Other way ’round usually. Underestimate costs to get funding, limit sampling to meet budget, waste money on pointless analysis of inadequate data, submit report to policy makers.

  2. Very well done listing of the complexities, and a nice theory (the 4 phases) advanced to try to group most of the complexities by their influence on pH. Makes recent attempts to plot pH trends look pretty simplistic.

    One minor glitch–the reported “113% decrease” in something. Wouldn’t a 100% decrease bring anything to zero?

    • “In the Atlantic, Steinberg (2012) describes a 113% decrease in diatoms between 1990 and 2007 in contrast to stable coccolithophore populations and a rapidly increasing community of photosynthesizing bacteria.”
      ———————————————–
      Does this work?

    • I agree there is something wrong with that percentage. It also gave me cause to pause and I apologize for not investigating it further. Originally I was going to use the graph from the original paper Lomas 2010 showing a sharp decline in diatoms but decide too many graphs get confusing. So I uncritically took the percentage from Steinberg 2012 who wrote, “Diatoms decreased in biomass by 113% from 1990 to 2007 based upon pigment analyses. Looking back at the original paper, Lomas reports a 113% decline in the “Period Change” but it is not very clear how that number was derived, but I assume he was comparing rates of change between 1990-1996 and 1997-2007. I am guessing but I imagine a 20% decline.year could decrease by 113% creating a 42.6% decline per year.

      The purpose of that number was to illustrate the sharp diatom decline and that remains accurate.

  3. Temperature, pH, ocean/air currents… time and time again, no baseline or range of variability is defined.

    This is not science…

  4. I was going to complain initially about the term “acidification” but he dealt with that bit first thing! Still, it’s very interesting to read.

      • It is correctly used, adding H+ ions is defined as acidification by chemists. Interesting that while he mentions ‘upwelling’ frequently, on my first read of it I see no mention of the equal amount of ‘downwelling’ which occurs, a startling omission.

      • The essay was a tad long as it is, and it would require a few books to adequately address all the issues. Downwelling usually prevent nutrients and DIC from reaching the surface and decreases the biological pump. So does downwelling create canceling effects? I don’t know and have not addressed papers that address that issue other than the effects of El Nino. Do you want to share research about the effects of downwelling on surface pH?

      • You could check this for a start, downwelling plus the descent of organic remains etc. exceed the upwelling contribution and that the net flux is from the atmosphere to the ocean.

      • Two Labs
        March 25, 2015 at 8:39 am

        Still, the term should be corrected.
        ——–
        That term exist and has a meaning only in the AGW “science”, as per the climatic context.
        It can not really be corrected unless and until it completely disappears altogether with the AGW itself.

        In a natural climatic context (a long term), the oceanic pH can be considered as a variation but it will be so insignificant as to be considered no any different from a constant,,,,,,,but then there again comes along the AGW and claims THE MERIT OF SUCH AS A TERM TO BE REGARDED….and then there again a furore about the meaning and definition of such a term bursts out…….

        cheers

      • Apparently the figure and associated reference didn’t load properly, here’s a different route to it.

      • Phil, and you provide any instances of where a solution in an acidic state becoming less acidic, is referred to as “alkalination?”

      • spren March 25, 2015 at 9:56 pm
        Phil, and you provide any instances of where a solution in an acidic state becoming less acidic, is referred to as “alkalization?”

        Not personally, since in titrations adjusting pH is usually done by adding acid to the basic solution the term ‘acidification’ is the appropriate one. The term ‘alkalization’ is apparently used in some medical treatments and remarkably in processing of chocolate powder!
        http://www.fpnotebook.com/Renal/Pharm/UrnAlklnztn.htm
        http://www.omanhene.com/tag/alkalized-cocoa-powder/

      • There seems to be a “startling omission” regards downwelling in the graph. So what is the point of the graph. It is not clear what it adds to the discussion.

      • jim Steele March 26, 2015 at 12:24 pm
        There seems to be a “startling omission” regards downwelling in the graph. So what is the point of the graph. It is not clear what it adds to the discussion.

        I’m not sure which graph you’re looking at, the one I posted shows net flux from atmosphere to surface of 2Pg, and downwelling of 33Pg from the mixed layer to below the thermocline. With the export of the soft tissue to below the thermocline the net transport downwards exceeds the upwelling by 2 Pg.

      • Yes I see that downward transport, so I think you have been using the word downwelling incorrectly. Downwelling refers to mass transport caused at convergent boundaries. Downward transport can occur for many reason but mostly in this case it is governed by the sinking rates of post mortem organisms and fecal pellets which I discussed extensively. So your mention of a “startling omission” is really just your misunderstanding.

      • jim Steele March 27, 2015 at 1:38 pm
        Yes I see that downward transport, so I think you have been using the word downwelling incorrectly. Downwelling refers to mass transport caused at convergent boundaries. Downward transport can occur for many reason but mostly in this case it is governed by the sinking rates of post mortem organisms and fecal pellets which I discussed extensively.

        Downwelling also covers downward transport by Thermohaline circulation. As is clearly indicated in the diagram I posted 33 Pg is transported by downwelling (which you do not address) as opposed to the 11 Pg of ‘post mortem organisms and fecal pellets’, so the transport is not mostly governed by the latter.
        Upwelling transport of sea water must be matched by downwelling due to continuity.

    • What term would you use to describe a reduction in pH? “Neutralization”? Neutralization of a basic solution is accomplished by acidifying the solution . . . acidification. Something else? “Ocean pH reduction”? A bit verbose wouldn’t you say? Again. Isn’t the process of pH reduction accomplished by acidifying the solution? If you consider the term inaccurate or wrong, that is fine. Please provide an alternate that is not obtuse.

      • There really is not an alternative. But, the problem is that the general public does not understand the characterization … they “know” that acid is harmful and therefore acidification is a bad thing in ALL cases.

        Any report or discussion that is intended for people with little or no understanding of the nomenclature/process needs to include clarification so as to keep the reader/listener/audience from being misled (intentionally or unintentionally).

        ANY discussion of “ocean acidification” is going to put a little scare into the general public unless there is adequate qualification showing that “acidification” is not the same evil that most people think it is.

        You may get tired of the repeated statements “its not acidification”, but it is necessary if you want anyone outside of your circle to understand what’s going on.

      • (scratch the last paragraph and add):

        We may get tired of the repeated statements “its not acidification”, but it is necessary if you want anyone outside of your circle to understand what’s going on.

    • Adding acid to a basic solution was always referred to as neutralising the solution. ‘Less basic’ or ‘more acidic’ are the same technically and were once more informative because, before this BS, you only used the latter to indicate that the pH will drop to less than 7. All chemists understood this. Do not lie about it.

      It gets warped into the oceans are becoming acidic eg “I’m very passionate about the oceans becoming acidic”, so the term neutralising should be used instead. If advertisers have to abide by the “moron in a hurry” rule, then so should scientists.

  5. An early source of my skepticism was an understanding of the buffering capability of the oceans and carbonates and hydrocarbons for any aliquot of CO2 man might inject. It was only later that I understood just how key the response of the biome is. Surely unthought of feedbacks are recruited in rising atmospheric and oceanic CO2 levels, and known ones enhanced.
    ====================

  6. I think Dr. Steele’s post is an excellent description of processes and pH variability. Most of the “acid ocean” scares ignore normal variability.

    Although Dr. Steele recognized that “acidic” didn’t really mean acidic by pH definition mentioned only two cases in which water was actually acidic (pH<7), as a chemist I found the use of the term meaning "lower pH" to make the reading more difficult. The use of the term acidic is misleading. Under this use pH 13.9 is more "acidic" than pH 14.0 because it contains about 26% more "hydrogen ions" (as does pH 0.9 compared to pH 1.0.) The use of the term "acidic" when discussing some upwellings made me pause and wonder if it was really pH<7, or just a lower (basic) pH than the upper water. In all the years I did chemistry things, if something was "acidified" you looked for a pH<7, now we could just be talking about pH 14 to pH 13.9.

    • I agree that the use of “acidic” is needlessly confusing; the proper words already exist, so use them.

      But perhaps being needlessly confusing is the goal! Which sounds more terrifying, and like it requires yet more funding and more control of peoples’ behaviors?

      — The oceans are becoming more acidic.
      — The oceans are become less alkaline.

      • Phil is correct (elsewhere) about pH vs total alkalinity.

        In response to someone’s comment, “A more correct and reasonable term would be ‘reduction in alkalinity’,” Phil said, “No it would not, the total alkalinity does not change when CO2 is added to seawater even if the pH changes.”

        Therefore, I should rephrase my post to read:

        Which sounds more terrifying, and like it requires yet more funding and more control of peoples’ behaviors?

        — The oceans are becoming more acidic.
        — The oceans are becoming less basic. [vs alkaline]

        Thanks Phil!

        * * * * *

        Science Demonstration: The Difference Between pH and Alkalinity

      • Max,

        Thanks for that video. It shows that the trace gas CO2 in the atmosphere cannot possibly cause measurable change in ocean pH, due to the oceans’ practically infinite buffering capacity.

        And another fake climate scare bites the dust…

      • they need to figure out where the carbon in calcium carbonate comes from….and it’s not from rocks

      • Latitude, some of it does come from rocks. Most of it comes from biological processes. Some of it from the rocks were previously biological. Complex is the word. The biology itself is incredibly complex because organisms with appreciable tenure on this wanky planet have developed access to carbonate through multiple biochemical pathways. This biochemical heritage is stored in multiple adaptive mechanisms as specific as prions and as general as genetic variation.

  7. …they simplistically argued declining ocean pH is “consistent with rising atmospheric CO2”.

    Richard Feynman once observed that if one chooses carefully the beginning and ending points of an argument, then almost any explanation is potentially consistent. He was arguing about classical explanations of magnetic properties of materials, but his point applies to almost everything else as well.

  8. Oh, heck, something went wrong with blockquotes. Try again…

    …they simplistically argued declining ocean pH is “consistent with rising atmospheric CO2”.

    Richard Feynman once observed that if one chooses carefully the beginning and ending points of an argument, then almost any explanation is potentially consistent. He was arguing about classical explanations of magnetic properties of materials, but his point applies to almost everything else as well.

  9. Very interesting.

    Dr. Steele wrote: “the ocean’s pH (thus the store of DIC) rapidly drops from 8.1 at the surface to 7.3 at 1000 meters depth”.

    This raises two questions: Why does the pH depend on depth? Why does lower pH imply lower DIC? If I dissolve CO2 in water, I lower the pH and raise the DIC. So I am guessing that what is going on is removal of carbonate as calcium carbonate. That would lower DIC and lower alkalinity, resulting in lower pH. Can anyone confirm that? Can anyone point me a source that describes the processes involved?

    In the meantime, I am going to see if I can find data on the DIC, alkalinity, pCO2 and pH as functions of depth.

  10. “[note: in this essay I use “acidic” in a relative sense. For example, although the pH of ocean water is 7.8 at 250 meters depth and is technically alkaline, those waters are “more acidic” relative to the surface pH of 8.1.]”

    No! Slightly less alkaline but still alkaline is not more acidic. The only time I have heard “acidic” used that way is by catastrophic global warming alarmists.

    Using such terminology is intended to alarm. For the uninitiated, less alkaline might sound like a good thing. More acidic doesn’t. Should scientists be propagandists? I don’t think so.

    • If normal for the ocean is 8.0, then 7.5 is acidic for the ocean. Just like -2C for the antarctic is warm.

      • the choice is not acidic and basic. It is acidic, neutral, basic.

        the ocean is becoming more neutral. if it is hot and the forecast is for a degree or two less, the weatherman will say “less uncomfortable” or “more comfortable”. he/she will not say “colder”.

        the issue is that the change is so small as to be insignificant, so the terminology must match.

    • If the pH of the ocean was 6 and climbing, scientists would say the ocean was growing more alkaline, they would not say less acidic. Would you consider that to be propagandist?

      When the peak temp is 100F and the forecast is for a peak of 90 the next day, does a meteorologist say “we forecast a less warming trend”? Of course not, they say cooling, even though technically it’s still warm.

      • Chris,

        The point is moot because there are no verifiable, testable measurements showing that ocean pH is changing. Error bars are far wider than any putative changes, so the whole “acidification” scare smacks of alarmist propaganda.

        Wake me when you (or anyone) can prove that ocean pH is changing outside of the error bars.

      • dbstealey,

        If the point is moot, why are so many climate change skeptics posting comments on this very issue, including the one I replied to?

      • Maybe a fundamental misunderstanding, Chris ? … go back a review the Hanna video … alkalinity is not a measure of pH, it is a buffer against acidification.

  11. In reply to ‘climate ‘scientist(s) could find experimental support for their favorite theory no matter what the theory claimed’.

    Climate science is chock full of urban legends. For example the hypothesis that the North Atlantic drift current is the reason for warm European winters is an urban legend. The hypothesis that insolation changes at 65N due to the orbital changes causes the glacial/interglacial cycle is an urban legend. Basic analysis in peer reviewed papers and all of the new findings concerning climate sensitivity to forcing changes unequivocally supports the assertion that both hypotheses urban legends, which have filled the theoretical void as the truth is climate scientists do not know what is the cause of the glacial interglacial cycle.

    Another of the long list of urban legends is the notion that there is a conveyor belt of deep cold water. Detailed experimental data indicates that hypothesis is an urban legend. Only 8% of the North Atlantic sinking water moves into what was assumed to be the deep ‘conveyor’. If one is sampling the deep ‘conveyor’ and it contains only 8% of the sinking water then there could be a significant under estimate of the amount of CO2 that is moving into the deep ocean.

    http://www.sciencedaily.com/releases/2009/05/090513130942.htm

    The familiar model of Atlantic ocean currents that shows a discrete “conveyor belt” of deep, cold water flowing southward from the Labrador Sea is probably all wet.
    New research led by Duke University and the Woods Hole Oceanographic Institution relied on an armada of sophisticated floats to show that much of this water, originating in the sea between Newfoundland and Greenland, is diverted generally eastward by the time it flows as far south as Massachusetts. From there it disburses to the depths in complex ways that are difficult to follow.

    To address those criticisms, Lozier and Bower launched 76 special Range and Fixing of Sound floats into the current south of the Labrador Sea between 2003 and 2006. Those “RAFOS” floats could stay submerged at 700 or 1,500 meters depth and still communicate their data for a range of about 1,000 kilometers using a network of special low frequency and amplitude seismic signals.

    But only 8 percent of the RAFOS floats’ followed the conveyor belt of the Deep Western Boundary Current, according to the Nature report. About 75 percent of them “escaped” that coast-hugging deep underwater pathway and instead drifted into the open ocean by the time they rounded the southern tail of the Grand Banks.

    Eight percent “is a remarkably low number in light of the expectation that the DWBC is the dominant pathway for Labrador Sea Water,” the researchers wrote.

    http://www.americanscientist.org/issues/pub/the-source-of-europes-mild-climate

    The Source of Europe’s Mild Climate
    The notion that the Gulf Stream is responsible for keeping Europe anomalously warm turns out to be a myth
    If you grow up in England, as I did, a few items of unquestioned wisdom are passed down to you from the preceding generation. Along with stories of a plucky island race with a glorious past and the benefits of drinking unbelievable quantities of milky tea, you will be told that England is blessed with its pleasant climate courtesy of the Gulf Stream, that huge current of warm water that flows northeast across the Atlantic from its source in the Gulf of Mexico. That the Gulf Stream is responsible for Europe’s mild winters is widely known and accepted, but, as I will show, it is nothing more than the earth-science equivalent of an urban legend.

    http://www.atmos.washington.edu/~david/Gulf.pdf

    Is the Gulf Stream responsible for Europe’s mild winters?
    By R. SEAGER, D. S. BATTISTI, J. YIN, N. GORDON, N. NAIK, A. C. CLEMENT and M. A. CANE

  12. Question for Jim Steele: Wouldn’t pH changes driven by upwelling, or by biological activity, produce changes in the ratio of total alkalinity to salinity?

    But the HOT data show a nearly constant ratio of total alkalinity to salinity.

  13. ‘First consider that oceans store 50 times more CO2 than the atmosphere.’

    Isn’t that foregoing statement somewhat overblown. True, the atmosphere obviously must surround 100% of the globe. But the oceans cover 70% of it. And true, the atmosphere can be considered as extending well above 100,000′ but at those altitudes it’s clearly quite rarefied. And, the ocean depths can extend to 35,000′. But, here’s the big thing: Isn’t the density differential between the oceans and the atmosphere something on the order of 1,000:1? So, a 50:1 storage differential between the oceans and atmosphere, in consideration of the foregoing, to me seems to represent, if anything, an actually surprisingly low level of CO2 in seawater compared to the atmosphere. Moreover, the atmospheric CO2 is measured in parts per million. Finally; some level of free CO2, before forming calcium carbonate, must still exist in seawater for life itself to exist. So, what’s the problem? Now, I’ll say that I stand open to correction by any commenter who’s more knowledgeable about this issue than I am since my knowledge is not particularly extensive.

    However, I feel quite strongly that the term ‘ocean acidification’ is deeply misleading. A more correct and reasonable term would be ‘reduction in alkalinity.’

    • A more correct and reasonable term would be ‘reduction in alkalinity.’
      No it would not, the total alkalinity does not change when CO2 is added to seawater even if the pH changes.

      • My understanding is that pH is a measure of the acidity or alkalinity of a solution. How could the pH change if pH is a measure when the thing being measured doesn’t?

        I’m not issuing an argument. Just a question.

      • Tom J,

        Since ocean pH remains within the error bars, there is no change. Therefore, there is ipso facto no change in pH. Anyone who argues otherwise does not understand what ‘error bars’ means [the hint is in ‘error’, as in ‘margin of’].

        The ‘acidification’ scare is not science. It is Belief, based on the runaway global warming scare; AKA: CO2=CAGW.

      • Tom J March 25, 2015 at 10:12 am
        My understanding is that pH is a measure of the acidity or alkalinity of a solution. How could the pH change if pH is a measure when the thing being measured doesn’t?

        I’m not issuing an argument. Just a question.

        pH is a measure of H+ ions, total alkalinity is something different and is usually defined as ‘the excess base’ in seawater, or the sum of excess proton acceptors, and includes carbonate, bicarbonate, borate, hydroxide, phosphate, silicate, nitrate, dissolved ammonia, the conjugate bases of some organic acids and sulfide. Ocean total alkalinity buffers, changes in ocean pH because of the presence of many different acid-base pairs. Total alkalinity remains constant when CO2 is added to seawater because the charge balance of the solution remains the same, because the number of positive ions generated is equal to the number of negative ions generated by these reactions.
        E.g.
        Here is the equation for Alkalinity:
        AT = [HCO3−] + 2[CO3−2] + [B(OH)4−] + [OH−] + 2[PO4−3] + [HPO4−2] + [SiO(OH)3−] − [H+] − [HSO4−] − [HF]

        Also CO2 + H2O → HCO3− + H+
        So the H+ changes the pH but the alkalinity is unaffected because the H+ is cancelled by the HCO3− (bolded terms). HTH

      • I’m not arguing with Phil. [for a change☺], but viewing Max Photon’s video upthread, it is crystal clear that there is not nearly enough CO2 in all the world’s unburned fossil fuels to measurably change the oceans’ pH.

        Thus, the ocean ‘acidification’ scare is another false alarm. It would have to rain pure vinegar for 40 days and 40 nights to move the pH needle…

      • It would have to rain pure vinegar for 40 days and 40 nights to move the pH needle…

        Interesting analogy since rain has about the same pH as apple cider vinegar. :-)

    • Tom J . No, you are mistaken to argue the CO2 is diluted over a greater volume. When CO2 outgasses it happens locally and can only happen when the pCO2 at the surface is greater than the pCO2 in the atmosphere.

    • Thank you all for the education. My knowledge (or lack thereof) is based on my old aquarium hobby days.

      Best wishes.

      • Tom … I’m an old marine aquarist (still am) this is fundamental to understanding marine aquarium water chemistry ;-)

      • We are fortunate in Broome off the NW coast of Australia, where massive 30 foot spring tides expose a mud sediment reef with the most amazing array of invertebrate critters, fish and plant-life. The colour of the sea is unusual here due to the suspended sediments, pushed around by a very strong at times, tidal flow. http://pindanpost.com/2015/03/25/low-tide-exposes-mud-reef/ It would be impossible to quantify, due to the many layers life present. There are no nearby large rivers to cause any large changes in salinity or alkalinity, but during summer, evaporation is very high, and the temperature can get too cold to swim in winter. http://pindanpost.com/2015/03/26/cable-beach-at-low-tide/ Many more photos can be seen here by searching “mud reef”.
        Thanks, Jim, an excellent article, makes a lot of sense.

  14. Good paper. Very interesting, and the primary point — that the oceans are enormously undersampled — applies just as strongly to flawed global temperature anomaly estimates, especially in the remote past. The simple fact of the matter is that we know a lot less about the state of world than we pretend that we do. This applies to the present, and is true, in spades, about the past. What we are hearing is much closer to a mythological narrative than sound science, with assumptions stated as fact, an utter contempt for error bars, without the vaguest semblance of proper statistical argument, and with grandstanding of egregious claims for severity of consequence that, in fact, have no proper foundation.

    rgb

    • This is a point that needs to be stressed: The temprature instrumental record is under sampled. It is mostly a function of human habitation, and only starts with the advent of the Farenheit scale in 1726. Humans prefer maritime and riparian habitat and the temperature sample reflects this bias. Just look at a map of population density:

  15. Jim Steele

    Thankyou very much indeed for your clear explanation of the issues that deserve much more public exposure than they get.

    For years I have been pointing out repeatedly and in many places (including WUWT) that the available data on ocean chemistry is far too sparse to enable conclusions on mechanisms of carbon exchange to and from the surface layer (both with the air and the deep ocean) especially when biological effects are significant and may be dominant. However, the common response is the mistaken assertion that Henry’s Law describes everything which – as you explain – is clearly not the case.

    Again, thankyou.

    Richard

  16. Mike M.:

    The solubility of gases increases with pressure. So any CO2 saturated water at increasingly greater depths will have a lower pH than above. But that is just a physical property. The increasing pressure will also stress the equilibrium between water CO2 and carbonic acid and cause and increase and carbonic acid and H+ ion, further decreasing pH.

    My comments: I appreciate Dr. Steele pointing out how complex the ocean pH issue is, those that want to characterize it as a simple Henry’s Law calculation are doing it a disservice. I would have thought those with scientific backgrounds would appreciate the complexities. But when they are more interested in pushing an agenda, having a sound bite with inaccurate information serves that purpose better.

  17. @Mike M. “Why does the pH depend on depth? ”

    In a word Gravity. Suspended DIC doesn’t sink and diffusion should bring more CO2 to the surface and outgas to the atmosphere. However the sequestering of CO2 via photosynthesis into heavy organic carbon compounds now carries the carbon downward. Rapidly sinking organisms like diatoms and coccolithophores will sink post mortem at rates of 200 to 500 meters per day. Photosynthetic cyanobacteria remain suspended but grazing zooplankton can aggregate them into sinking fecal pellets. Fast sinking rates deposits their remains in the ocean sediments. Likewise some organic compounds are “refractory” and are not be broken down further. Much of the ocean’s proxy data takes advantage of those compounds which are specific to certain plankton species.

    Notice in the first graph that the northern Pacific pH minimum happens around 1000 meters depth. This typically coincides with oxygen minimum zones marking the boundary where bacterial decomposition of sinking organic material leads to greatest extend of “re-minieralization” of organic molecules. The lack of oxygen also causes denitrification promoting the diffusion of molecular nitrogen back to the atmosphere. But to complicate things nitrogen fixing bacteria thrive in minimal oxygen zones.

    When upwelled those oxygen depleted waters cause temporary die-offs of benthic dwelling organisms. And of course that natural phenomenon is blamed on global warming.

    • Jim Steele,

      But if the sinking organisms are “re-mineralized” (that means converted back to inorganic carbon?) at depth, would that not increase the alkalinity at depth and increase the pH? And if they sink all the way to the bottom, that has no effect on the water in between. Does alkalinity decline with depth? If so, what causes that?

  18. You lost me at “ocean acidification” since what they’re talking about is the ocean becoming slightly less basic. Precison counts in science.

    • I’m really, really fed up with this annoying comment, which comes up ad nauseam every time we discuss pH.
      I’m totally relaxed, as a sceptic, about the use of ‘acidification’ in this context, and I don’t see it as a “loaded” useage particularly associated with the AGW community. I can’t see any chemist being offended by it: the useage seems perfectly correct to me. Please, let it be! Hold your fire for the real issues.

      Nice post, Dr Steele. Once again, we see the astonishing capacity of the natural world to accommodate, adapt to, and usually to restore the global environment. The gaia idea has considerable utility.

      • The correct term may be “mulatto” but you would only use that term to describe POTUS if you had some hidden agenda, wouldn’t you?
        When they use the term “acidic” for the purpose of driving irrational fear for an agenda, that’s not science.

      • Yes, Mike. The fact is that the oceans are still very basic. If anyone believes that a change in an atmospheric trace gas will cause the oceans to become acidic, then they are commenting out of ignorance.

        It’s like being outdoors in a t-shirt when it’s 40ºF, and saying saying that you’re cold. If the temperature goes up to 42º, you wouldn’t say you were “warm”. Most folks wouldn’t even say they’re “warming”. And that would be a bigger change than what is being claimed for ocean pH.

        Same with any putative change in pH. The oceans are still very basic. Further: there are no verifiable, testable measurements showing that ocean pH has changed at all — as shown in the very first post in this thread.

  19. @ Mike M. “Wouldn’t pH changes driven by upwelling, or by biological activity, produce changes in the ratio of total alkalinity to salinity?”

    Indeed regional alkalinity and salinity track each other closely, and researchers will used salinity as a proxy for alkalinity. Carbonate ions form about 9% of the total DIC, and that is what organisms use to produce their calcium carbonate shells. If you read the paper I linked to Bates 1996, they observed a change in alkalinity that diverged from what salinity predicted and attributed that change to blooms in coccolithophores that pump alkalinity to lower depths. The biological dynamics is thus called the alkalinity pump.

    Also understand that there are cyclical changes in salinity. The North Pacific Gyre Oscillation is a measure of changing salinity over a period of about 18 years.

  20. Solar insolation is the amount of solar irradiance (the entire spectrum) reaching Earth’s ocean surface. Your conclusion includes a reference to decreasing solar insolation, “If history repeats itself, declining solar insolation will result in less upwelling, lower productivity, a reduced biological pump and higher pH”. What reconstruction are you using to say that insolation decreased in the past (I would like to know this since I am unaware of such a reconstruction)? And did the TOA solar irradiance decrease in the past? And if you think it did, what reconstruction are you using to say that solar irradiance decrease may have been a part of history? I have posted some references to this issue:

    Here is an earlier paper describing the complicated search for connections.
    http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20000081668_2000118140.pdf

    Here is a current powerpoint describing whether or not correlations exist in reconstructions
    http://www.leif.org/research/Solar-Activity-and-the-Earth.ppt

    Here is a work in progress describing extreme ultraviolet reconstructions (an important discussion because several commentators have reasoned that since the more variable solar EUV penetrates deeply into the ocean, this could be a cause of ocean warming)
    http://www.leif.org/research/Reconstruction-of-Solar-EUV-Flux-1834-2014.pdf

    • Mr. Steele

      Nice job! Bookmark worthy for sure.

      I am a little concerned with your use of “acidic” even though I think your note makes it clear to most any reader how your using the term. Technically, “acidic waters” would have to be waters less than 7 pH whereas ‘more acidic waters’ would be water with a lower pH regardless of pH (relative).

    • Pamela I used the term solar insolation to include all dynamics by which solar energy reaches the surface including changes in solar irradiance, orbital effects and changes in cloud cover such as observed during El Nino/La Nina cycles, as La-Nina like conditions correlate with increased solar output. Granted there is much debate about the solar connection and to what degree solar irradiation changed, but most would agree that during the Little Ice Age there was a drop in solar irradiation as well as a drop during the Last Glacial Maximum. I would have to go back to each of those papers before I can tell which reconstructions they used.

  21. Regards my use of the term acidification. I totally understand that it has been used to evoke alarm. But when discussing the issue with warmists, they are not swayed by the technical accuracy. To them pH is declining and nitpicking the word is irrelevant and often seen as slippery denial. In contrast, arguments that declining pH can be driven by upwelling and biological cycles gave them pause to stop and reconsider. So I chose not to battle with the common, but incorrect usage of “ocean acidification” and focus on the more important mechanisms, so hopefully someone searching the internet to learn about “ocean acidification” will get a balanced perspective.

  22. “Granted when all else is equal, higher atmospheric CO2 concentrations result in more CO2 entering the oceans and declining pH.”

    However, seawater is a complex buffer and a little added CO2 is unlikely to swamp it out. Reality trumps speculation, the latter shown above would only be true for distilled water. How far from reality is this thinking going to go?

    Also, as CO2 to carbonic acid to bicarbonate ion to carbonate ion to calcium carbonate solid is one long equilibrium, the protons from this equilibrium cannot effect their won equilibrium. Only an outside source of protons could push this equilibrium around. More CO2 means more calcium carbonate deposition. Coral reefs simply LOVE MORE CO2. The world’s coral reefs have been growing 30–50% faster then they were 50 years ago.

      • “I suggest you revisit Le Chatelier’s principle, CO2 does indeed control the equilibrium position.” In a titration experiment back at the lab, yes, but in the ocean with salts readily going into and out of solution, no.

      • Phil.

        I suggest you revisit the article above this thread (assuming you have read it). Biology does indeed control the equilibrium position in many circumstances and that “position” is rarely achieved.

        Other factors such as injection of dissolved sulphur (e.g. from submarine volcanism) may also be pertinent in some localities.

        I have repeatedly explained these matters to you in previous WUWT threads but you refuse to understand them.

        As I said in my above post, I am grateful to Jim Steele for the publicity he has given these matters because their complexity requires such publicity to overcome the naive soundbites from such as you. Henry’s Law and Le Chatelier’s principle are simplistic concepts that can mislead when applied to complex biological systems.

        Richard

      • Richard I have explained to you in the past the errors in your chemistry and I’m not going to waste my time repeating it.
        RWturner, Le Chatelier’s principle applies even in a complex system such as the ocean, most of the ions present are in constant ratio to each other. The principle variable ones are bicarbonate and carbonate which are influenced by the concentration of CO2 which depends on the atmospheric pCO2.

      • Phil.

        You make the laughable assertion to me

        Richard I have explained to you in the past the errors in your chemistry and I’m not going to waste my time repeating it.

        No, Phil.. You have repeatedly made a fool of yourself by spouting nonsense you don’t understand.

        In this case the chemistry under discussion is that stated in the above article by Jim Steele. I agree it. Indeed, in previous WUWT threads I have repeatedly tried – and failed – to get you to understand it.

        Perhaps you could explain what you think to be the “errors” in the chemistry in the above article? Or are you willing to allow your assertion I have here quoted to demonstrate your inability to substantiate your simplistic and fallacious assertions concerning ocean chemistry?

        Richard

      • Phil, pCO2 would effect the equilibrium if the supply of carbonate and bicarbonate were fixed, but it’s not. CaCO3 sediment readily goes into and out of solution.

      • Phil. comes from the point of view that human CO2 emissions are causing global problems.

        When that is your belief [rather than taking all the evidence, and considering what it tells us], then it becomes an agenda, and factiods are cherry-picked to support the position.

        Phil. is a smart guy. But belief is stronger than intelligence. As Prof Feynman cautions, fooling yourself is something to always beware of.

      • Phil all Le Chatelier’s principle says if equilibrium is disturbed the system will adjust in the direction of a new equilibrium. If upwelling brings more DIC to the surface, the adjustment is outgassing. If the biological pump reduces DIC the adjustment is the surface layer become a sink. But it is the strength of the biological pump that determines the pH equilibrium position. Diffusion of CO2 into the upper oceans is a relatively slow process. Mixing by wind is critical. Because equilibrium happens slowly, and the ocean pCO2 changes faster than the atmospheric pCO2, if the biological pump strengthens, then pH rises. If the pump weakens then pH will fall. So what’s your point?

      • Jim:

        Mixing by wind is critical.

        Likewise, if I’m correct in my thinking, wind is essential to outgassing of CO2 as well … take a beaker of natural seawater, measure its pH, bubble fresh air through it with an airstone … pH rises as the CO2 is outgassed.

      • RWturner March 25, 2015 at 1:18 pm
        Phil, pCO2 would effect the equilibrium if the supply of carbonate and bicarbonate were fixed, but it’s not. CaCO3 sediment readily goes into and out of solution.

        The timescale of dissolution of CaCO3 is much slower than the rate of dissolution of CO2 due to increasing pCO2 so your sediments are not relevant.

      • Streetcred March 25, 2015 at 8:41 pm
        Jim:
        Mixing by wind is critical.
        Likewise, if I’m correct in my thinking, wind is essential to outgassing of CO2 as well … take a beaker of natural seawater, measure its pH, bubble fresh air through it with an airstone … pH rises as the CO2 is outgassed.

        The effect of wind is to change the rate of transfer across the boundary, the ultimate concentration is not affected. In the example you quote the pH would not rise because the bubbling of air (which contains CO2) would maintain the CO2 concentration at the equilibrium value.

        richardscourtney March 25, 2015 at 11:47 am
        Phil.

        I suggest you revisit the article above this thread (assuming you have read it). Biology does indeed control the equilibrium position in many circumstances and that “position” is rarely achieved.

        Biology does not control the equilibrium position that is controlled by the chemistry, Henry’s Law controls the ratio between the atmosphere and the surface water and chemical equilibria control the ratios CO2/HCO3-/CO3–. Any change in CO2 by biological process will be offset by shifts in those equilibria, at certain times, e.g. during an algal bloom, there will be a temporary excursion from equilibrium but the chemical processes will be attempting a return to that equilibrium.

        dbstealey March 25, 2015 at 4:00 pm
        Phil. comes from the point of view that human CO2 emissions are causing global problems.

        No, I come from the point of view of an experienced PhD in physical chemistry who corrects mis-statements about the chemistry, in particular from guys like courtney with an agenda, who has a high school knowledge of chemistry and tries to preach on the subject.

      • Phil, Below you wrote “Any change in CO2 by biological process will be offset by shifts in those equilibria, at certain times, e.g. during an algal bloom, there will be a temporary excursion from equilibrium but the chemical processes will be attempting a return to that equilibrium.”

        When you argue against biological processes via chemical equilibrium arguments you are being a tad misleading. The chemical equilibrium is determined by the concentrations. If upwelling increases DIC concentrations at the surface, then new equilibrium is a lower pH. If biological processes remove DIC the new equlibrium is a higher pH.

        Based on boron isotope/foraminifera data the upwelling of the deglacial period moved the equilibrium point of surface waters from 8.4 to 8.1 over the course of 20,000 years despite lower atmospheric CO2concentrations. You are misleadingly stating your arguments as if there is some magical equilibrium point independent of biological and upwelling processes. If the ocean’s overall alkalanity does favor a equilibrium point, it is the point observed during glacial periods when upwelling and productivity were reduced and ph hovered closer to 8.4. Compared to upwelling, atmospheric CO2 is relatively insignificant.

      • jim Steele March 26, 2015 at 10:43 am
        Phil, Below you wrote “Any change in CO2 by biological process will be offset by shifts in those equilibria, at certain times, e.g. during an algal bloom, there will be a temporary excursion from equilibrium but the chemical processes will be attempting a return to that equilibrium.”

        When you argue against biological processes via chemical equilibrium arguments you are being a tad misleading. The chemical equilibrium is determined by the concentrations.

        No it is not, it is defined by the equilibrium constant, which in turn is a function of temperature.
        If a volume of sea water is at a temperature of 25ºC in contact with an atmosphere containing 400 µatm of CO2 its ultimate composition will be mostly bicarbonate, some carbonate and CO2 in equilibrium with the atmospheric pCO2. Introduce some photosynthetic activity and some CO2 will be consumed which will be replaced by absorption from the atmosphere and decomposition of bicarbonate:
        HCO3- -> CO2 + H+
        until equilibrium is restored.
        In the case of an algal bloom the CO2 can be removed faster than it can be replaced then the CO2 concentration will drop, however once the photosynthesis slows then there is a return to the original equilibrium composition.

        If upwelling increases DIC concentrations at the surface, then new equilibrium is a lower pH.

        Upwelling isn’t a ‘biological process’! However, the equilibrium composition will depend on the temperature, at the surface if the equilibrium composition of CO2 exceeds the Henry’s Law value then CO2 will outgas to the atmosphere.

        You are misleadingly stating your arguments as if there is some magical equilibrium point independent of biological and upwelling processes.

        It’s not ‘magical’ it’s real and defined by the thermodynamics.

      • jim Steele March 25, 2015 at 6:24 pm
        Phil all Le Chatelier’s principle says if equilibrium is disturbed the system will adjust in the direction of a new equilibrium.

        This appears to be the source of your error, Le Chatelier’s principle states that if an equilibrium is disturbed the system will readjust to restore the equilibrium, not a new equilibrium.

      • Phil says,”Le Chatelier’s principle states that if an equilibrium is disturbed the system will readjust to restore the equilibrium, not a new equilibrium.”

        You are playing with words. If I have a DIC concentration the yields a 7.7 pH and an equilibrium approximating 1% CO2, 90% HCO3-, and 9%CO3 -, and I remove 50% of the HCO3- , a equilibrium with the same 1:90:9 ratios will be restored, but it will adjust to a new pH

    • jim Steele

      I see you have experienced the problem of Phil. refusing to understand the realities of ocean chemistry.

      You have told him he is wrong and you have explained why he is wrong when he asserts that Henry’s Law describes everything. But, as I have repeatedly experienced in the past, he simply refuses to understand.

      For example, in response to your having said

      If upwelling increases DIC concentrations at the surface, then new equilibrium is a lower pH.

      he has replied

      Upwelling isn’t a ‘biological process’! However, the equilibrium composition will depend on the temperature, at the surface if the equilibrium composition of CO2 exceeds the Henry’s Law value then CO2 will outgas to the atmosphere.

      So he has ignored your comment about “DIC concentrations” and talked about “temperature”. This non sequitur is typical of how he responds to information he finds inconvenient: i.e. he ignores the information and talks about something else.

      Your cogent explanation uses different words than my many attempts to explain effects of upwelling to Phil., but your explanation has received the same response as I have always obtained.

      I strongly suggest you leave it at that. Every impartial observer can see you are right and history indicates Phil. is incapable of admitting he is wrong.

      Richard

      • richardscourtney March 26, 2015 at 9:06 pm
        jim Steele

        I see you have experienced the problem of Phil. refusing to understand the realities of ocean chemistry.

        You have told him he is wrong and you have explained why he is wrong when he asserts that Henry’s Law describes everything. But, as I have repeatedly experienced in the past, he simply refuses to understand.

        Reading comprehension hasn’t improved I see richard.

      • Phil.

        It is good that you at last admit your failings at reading comprehension. But admitting your problem is not enough: you now need to correct it.

        Richard

  23. It is always a joy to read Dr. Steele’s incisive articles here.

    Dr. Murry Salby recently gave his latest lecture explaining why CO2 in the atmosphere is not controlled by humans. it is of particular note to me that temperatures in the Southern hemisphere, where most of the ocean area is, show particularly good correlation with atmospheric CO2 rate of change.

    It is clear that a temperature modulated, non-anthropogenic, process is the main driver of atmospheric CO2, and it is likely due primarily to a complex interplay between oceans and atmosphere.

  24. Jim , Thanks for a readable paper that makes a great deal of sense. Life is complex and and CO2 is a part of that complexity. In that you explained so much of the complexity it to me has the sound of truth to it. Thanks again.

  25. Nice article but it missed two key points:

    1. Basic ions are continuously being delivered to the oceans via rivers in very large amounts each year, but they have been doing this for billions of years and the result we see today is the ions, salts, and marine sedimentary rocks today. Suggesting a small change in atmospheric CO2 will alter the chemistry of this 4 billion year accumulation of ions/salts within sea water is laughable.

    2. The result of this 4 billion year transport of ions to the oceans is a supersaturation with respect to CaCO3 in shallow water and the subsequent CaCO3 sediments comprising the shallow sea floor. Shallow water CaCO3 sediments are in direct contact with ocean water and will dissolve into solution before actively growing CaCO3 shells will. CaCO3 producing organisms not only change the pH of the surrounding water but actually change the pH at the shell/water interface, creating an artificially high pH at the sight of CaCO3 nucleation on the shell. CaCO3 sediment does not have this biologic forcing to counteract dissolution so these sediments are in constant flux between precipitation and dissolution within sea water which is always moving towards stoichiometric equilibrium with respect to temperature, pressure, and dissolved ion load.

    No amount of CO2 from fossil fuels will ever exhaust this direct source of CaCO3 salts readily available to keep equilibrium within shallow seawater. In fact, aragonite, the most easily dissolved polymorph of CaCO3, is still precipitating without biologic forcing within shallow seawater forming oolites on shoals around the Bahamas, Persian Gulf, and northwest Australia, as well as in whitings in the Caribbean and Persian Gulf. If the alarmists wanted to make a case for alarm using empirical data, not models or oversimplified experiments in fish tanks, they could easily show that oolites in modern seas are responding to their fantasy of ocean acidification because it’s these inorganically precipitated aragonite sediments that would respond to changes in pH first. Turns out modern oolites are still there, they’re still forming, and climastrologists don’t have a leg to stand on.

    Here’s just one of the many examples of the carbonate sediment/seawater interactions:
    http://link.springer.com/article/10.1007/BF02784696

    • I assume you are referring to this:
      surface waters to 1000 matm, 2.5 times above atmospheric pCO2
      It should be 1000 µatm, either a typo or the result of a change in font.

      • Yes the original was 1000 µatm but the font change translated it to matm. Thanks for pointing this out. I need to correct this at my website as well.

  26. Mr. Steele,
    Thank you for such a clear article- just like all the articles in your book- (If any of you haven’t read or purchased it,(Landscapes and Cycles) it is FANTASTIC !) I love your approach to making your arguments with respect and consideration of the other viewpoint- and that you acknowledge the science is NOT settled. Your point is well taken that there is a lot more to the ocean acification than just C02 dissolves in the ocean and therefore becomes more acidic. This is so over simplified- (Just like the whole CAGW debate) and you do a great job of clarifying what some of the other important issues are. I hope you continue to be a great educator here. Your students must have loved having you as a teacher- you found your calling. Lucky for us! :)

  27. “…the construction of coccoliths metabolically increases surface pCO2, lowers pH and counteracts the “biological pump”. When calcium combines with carbonate ions to form coccoliths, the reaction releases acidifying CO2.”
    No. The complete, balanced process, comprising photosynthesis and test formation is: Ca2+ + HCO3- → CaCO3 + CH2O + O2. There is no net CO2 production and no acidification. In the case of diatoms, which produce siliceous tests, on the other hand, hydroxyl is a by-product, and that does lower pH.

    • David you are assuming that all the CO2 released by coccolith formation is consumed by photosynthesis, but those processes is not that tightly coupled. And the process also decreases alkalinity in the surface and pumps alkalinity to depth. There is no argument there.

      • David read the Bates 1996 paper that I linked to at the end of the essay. There are references in that paper and here is a relevant excerpt:

        If all freed CO, is fixed, the ratios of organic to inorganic carbon production or TA:TCO, depletion should be 1:l and seawater pC0, should not change. If calcification rates are higher than fixation rates, excess CO, may return to the external seawater increasing pCO,, while decreasing alkalinity (TA) and total carbon
        dioxide (TCO,) in a ratio between 1:l and 2: 1. Recent experimental studies indicate that calcification rates in coccolithophorids can exceed fixation rates, especially under phosphate limitation (Bleijswijk et al., 1994; Paasche and Brubak, 1994), where seawater pC0, increased in 11 m3 size mesocosms enclosures of E. huxleyi (Purdie and Finch, 1995). Robertson et al. (1994), on the other hand, reported 1:l organic to inorganic carbon ratios and a reduction in the air-sea gradient of CO, within E. huxleyi blooms in the northeast Atlantic. In contrast to coccolithophorids, calcification in foraminifera should lead to an increase in seawater pC0, since the uptake of HC03- or CO:- reduces alkalinity (TA) and TCO, in a ratio of 2:l.

  28. I was shocked when I first looked at the data for the claimed ocean acidification a couple of years ago. The sheer audacity of the propaganda. The scary world maps with red zones highlighting PH levels of 8.05 compared to 8.2. I asked myself, how are they getting away with this? It was the final straw for me and I’ve not trusted an environmentalist on any issue scince.

      • Phil. says: March 25, 2015 at 4:47 pm You have a problem with a 40% increase in [H+]?
        ———————-

        Case in point wicked! On cue.

  29. What a superb essay.

    Several researchers suggest coccolith formation evolved to provide much needed CO2 for photosynthesis in under-saturated waters. Experimental evidence reveals higher concentrations of CO2 results in lower rates of coccolith formation.

    Note that the response here is a lower rate of formation and not an increased rate of dissolution.

    However the same response would be expected if the rate of coccolith formation responds to the available supply of CO2 required for photosynthesis.

    Yes!

  30. Two other points: first, the rise in atmospheric CO2 lagging temperature rise after the LGM could also, and more simply, be explained by CO2 exsolving from the warming ocean due to its decreasing solubility in water with rising temperature. The consistent lag of CO2 with respect to temperature in the Vostok ice core is another example. The lag is short with rising temperature, but up to 5 times longer with falling temperature due to the long residence time of CO2 in the atmosphere. The other point is that the decline in oceanic pH following the LGM could be due to the massive amounts of sulfate emitted during the prodigious volcanism that accompanied the Preboreal warming.

  31. And another! It’s possible that the greater ratio of coccolithophores to diatoms during the LGM might simply be due to the lower temperature of the oceans at that time, favoring a higher concentration of CO2 available for test formation. The same argument could be applied to the increased dominance of coccolithophores over the past 5000 years.

  32. I really despise, even for the sake of argument, calling water in an alkaline state “acidic.” In the same fashion I could say that water temperature in the river behind my house, changing from 48 degrees to 42 degrees is becoming more “frozen.” The use of the term “acidic” in these scientific discussions provides a threatening tone to laymen, hence their use. Describing what is actually happening as a lower alkalinity does not carry the same emotional impact and does not accomplish the desire effect of increasing concern.

    • As explained above describing it as ‘lower alkalinity’ is wrong, I agree that calling water at pH 8 ‘acidic’ is incorrect but the correct term for increasing H+ is ‘acidification’, it is not ‘neutralization’ as that refers to adding exactly the correct amount of acid to make the resulting solution neutral.

  33. Last Thursday, the Australian ABC program Catalyst ran what seemed to be a a scare program showing a group of scientists conducting an experiment in shallow waters under 2 metres of ice in the Antarctic to prove that increased acidification harmed the formation and growth of krill. They laid down several small closed chambers with different ph levels to test or prove their hypothesis. My first concern was “what! in such shallow waters and in such a small area”. I wish I had the knowledge to call them out on this. It just didn’t seem to be a valid scientific endeavour. The article above just seemed to fit what they seemed to be doing – undersampling and eventually proving what they set out to prove.

  34. The modelled drop in pH is a load of twaddle. There is no real data showing any change.

    For millions of years, rivers, somewhat acidic, and rain, somewhat acidic have fed into the oceans,

    yet the oceans remain steadfastly around pH 8 point something

  35. Nice article! Still a few questions:

    Those higher fluxes of CO2 into the surface likely stimulated a more efficient biological pump resulting in higher pH.

    Seems to be from one (tank) experiment at 1x, 2x and 3x CO2. My impression of the real oceans was that CO2 was not the limiting factor in any oceans, but that nutrients were the problem.
    The summer-winter variability in DIC even in sub-polar waters where the largest difference in temperature and life can be found is not more than 60 μmol on a total of over 2000 μmol nDIC, far from the factor 2-3 which can be found in forests on land between day and night, where CO2 indeed can be a limiting factor (but even there…).

    Due to ocean buffer chemistry, the change in DIC is only 10% of the change in the atmosphere (the Revelle factor), thus the 30% increase in the atmosphere over the past 160 years is good for not more than a 3% DIC increase in the ocean surface. That hardly will enhance any growth speed of biological life in the oceans. It seems to me that the influence of the increased CO2 on the pH is more important that its effect on the biological pump, moreover that even such a negative feedback wouldn’t surpass the original disturbance…

    The main objection I have is that you conclude that the trend can go anywhere, based on the variability around the trend. But while the variability is caused by a lot of influences, including upwelling, temperature, bio-life,… the trend in DIC and pH over the past 30 years is quite consistent with the increase of CO2 in the atmosphere for all fixed measurement places over all oceans and already exceeds the seasonal and year by year natural variability, except at high upwelling or high wind mixing zones.

  36. Jim,

    From your reply above March 25, 2015 @ 6:40pm you state:

    If calcification rates are higher than fixation rates, excess CO, may return to the external seawater increasing pCO & Recent experimental studies indicate that calcification rates in coccolithophorids can exceed fixation rates, especially under phosphate limitation.

    I understand from this that the formation of aragonite from seawater by the marine algae as they recover carbon dioxide from bicarbonate solution is “leaky” and also that this biochemical process of carbon dioxide liberation operates independently from the process of photosynthetic fixation. Therefore at times of phosphate limitation stress the coccolithophorids become a net source of dissolved carbon dioxide in the seawater.

    BTW It is not easy to find out what MATM means.
    This from Deep Sea Research Part I: Oceanographic Research Papers Volume 58, Issue 12, December 2011

    We propose the unit milli-atmospheres (matm) be adopted as standard unit for oxygen thresholds and contents to facilitate a later combination of pO2 fields with pCO2 fields, which generally are reported on μatmμatm units (e.g. Zeebe and Wolf-Gladrow, 2001, Meehl et al., 2007, IPCC, 2007 and Brewer and Peltzer, 2009), for assessment of combined effects of temperature change and ocean acidification.

  37. Ferdinand says “the trend in DIC and pH over the past 30 years is quite consistent with the increase of CO2 in the atmosphere for all fixed measurement places over all oceans and already exceeds the seasonal and year by year natural variability, except at high upwelling or high wind mixing zones.”

    I suggest that due to undersampling we can not reliably conclude anything meaningful. Indeed you can argue that pH changes are consistent with the increases in atmospheric CO2, but I would counter that pH trends are equally explainable from upwelling of DIC from depths where much greater concentrations of DIC reside . Since the Little Ice Age ended (which coincides with the industrial age) upwelling has increased and that suggests a declining trend in pH. Although upwelling dominates coastal and equatorial zones, the effects are cetainly not restricted to just coastal regions.

    Organic carbon produced in highly productive upwelling zones has components that remain suspended in the upper layers of the ocean and that carbon is advected 100s to thousands of miles away. Ekman pumping advects suspended organic carbon seaward towards the center of the subtropical gyres and there researchers (mysteriously?) find increasing mesozooplankton biomass that contradicts the notion that global warming will decrease vertical influxes of nutrients and decrease photosynthesis and carbon fixation. But due to advection of nutrients from upwelling zones, subtropical gyres have observed increased community respiration rates vs photosynthesis. That can not be possible unless organic carbon is arriving from elsewhere and an increased ration of respiration is equally consistent with a declining trend in pH.

    Furthermore you refer to results from “one tank” to refute possible CO2 enhancement of photosynthesis. But there are many more papers besides the “one tank study” discussing the positive feedbacks from increased CO2. Dore’s observation cited above for example, and references cited by Riebesell. Additionally most phytoplankton are now operating under reduced concentrations of CO2, than when they first became abundant suggesting they are now operating under more stressful and limited CO2 conditions. Finally numerous studies show phytoplankton have evolved various methods to concentrate CO2 due to undersaturation, because the surface waters are undersaturated relative to the efficiency of RuBP that fixes CO2 for photosynthesis.

    My argument stands that until the natural cycles of upwelling and the biological pump are better elucidated, any opinion that states changes in surface pH are consistent with atmospheric CO2 remains nothing more than an opinion.

    • Jim,

      Most experiments with enhanced CO2 were with CO2 doubling and tripling. The current increase is only 30%, which did give (theoretically) a 3% increase of DIC. Seems rather negligible as growth enhancement. Even the 30% increase in the atmosphere is only good for a ~1 GtC/year extra uptake by land plants over a ~60 GtC/year cycle… Which doesn’t say that there is no influence, as indeed coccoliths and corals did evolve in atmospheres and oceans with much higher CO2/bi/carbonate levels. Be it that Ca/Mg in the oceans was also much higher, I suppose…

      More upwelling from the deep oceans would have a similar effect, but that also would increase CO2 in the atmosphere. Which is difficult to balance with the extra mass of CO2 from human origin where only halve – as mass – remains in the atmosphere from all combined extra sources. Even balanced by a faster source-sink cycle has no supporting observations…

      • I am not clear about your point or your suggestion about upwelling. Upwelling has been observed to bring enough DIC to the surface that pCO2 in the surface is 2 to 3x the atmosphere.

      • Jim, there is a variable upwelling near several coasts with the largest one near the Peruvian/Chilean coasts, that one is heavily influenced by ENSO. With increased upwelling, more CO2 should enter the atmosphere at 2-3 times the atmospheric pressure, but the net result seems reverse, thanks to (tropical land and sea) bio-life: La Niña conditions give more upwelling and less increase of CO2, reverse for El Niño conditions.
        Anyway, the equatorial waters have the highest pCO2 over the atmosphere while polar waters have the lowest pCO2 under the atmospheric CO2 pressure. That gives a near continuous flux of CO2 through the atmosphere from the equator to the poles of around 40 GtC/year which returns via the (deep) oceans many centuries later.
        The 40 GtC/year can be deduced from the 14C/12C (atomic bomb tests) and 13C/12C (fossil fuels) declines where the current isotopic composition enters the oceans (minus the isotopic shift at the surface) but the isotopic composition of ~1000 years ago returns to the atmosphere (minus the isotopic shift at the surface).

        Further on:
        My argument stands that until the natural cycles of upwelling and the biological pump are better elucidated, any opinion that states changes in surface pH are consistent with atmospheric CO2 remains nothing more than an opinion.

        Depends of how large the variations in the natural cycles are and how alternative explanations fit the observations. Overall, the natural variation in rate of change is about +/- 1 ppmv/year around the trend, with little change over the past 55 years: lower with cooler years (Pinatubo, La Niña) higher with warmer years (El Niño). The trend itself increased from about 0.5 ppmv/year to 2 ppmv/year while human emissions increased from about 1 ppmv/year to over 4 ppmv/year. All three main variables: human emissions, increase in the atmosphere and sink rate show similar behavior and increased a 4-fold in the past 55 years:

        Human emissions fit all observations in the atmosphere and the oceans. Alternative explanations should fit all observations too, but all alternatives I have heard of fail one or more observations. Take e.g. the deep ocean upwelling: deep oceans have a 13C/12C ratio around zero per mil. Ocean surfaces have a 13C/12C ratio of +1 to +5 per mil, depending of bio-life. An increase in upwelling would give a small change in 13C/12C of the surface, in which direction is the question, as more upwelling gives more bio-life. What is observed is the strong decline in 13C/12C ratio as well as in the atmosphere as in the ocean surface layer, completely paralleling human emissions over the past 600 years:

        Of course, that is a one-spot trend, but sponges in the Pacific show similar trends, be it disturbed by episodes of increased upwelling (= upward 13C/12C ratio shift!).
        Besides the mass balance, that effectively refutes the possibility of increased ocean upwelling as cause of the declining pH and increasing DIC in the oceans and increasing CO2 in the atmosphere…

    • The sponges paper is from Böhm e.a., “Evidence for preindustrial variations in the marine surface
      water carbonate system from coralline sponges”, G3, published by AGU and Geochemical Society. A preprint is here:
      http://www.boehmf.de/Boehm_et_al_g_cubed_preprint.pdf

      The sink rate is simply the difference between calculated emissions (based on fossil fuel sales and burning efficiency) and the increase in the atmosphere, without looking at individual sources and sinks, thus just the mass balance. A more detailed partitioning between biosphere and oceans can be deduced from the oxygen and 13C/12C ratio balances:
      http://www.sciencemag.org/content/287/5462/2467.short
      and
      http://www.bowdoin.edu/~mbattle/papers_posters_and_talks/BenderGBC2005.pdf

      The ocean surface has a fast exchange (1-3 years) with the atmosphere, but has a limited buffer capacity. The deep oceans have far more capacity, but are more limited in exchange rate as that is limited to upwelling and downwelling places and the biological pump. The biosphere sink is even slower: while the seasonal exchanges are enormous ( ~60 GtC in and out over a year), the net uptake is only around 1 GtC/year for a pressure increase of 110 μatm above the long term equilibrium…
      Other sources and sinks are either too small or too slow to have had much impact over the past 160 years.

  38. @ Philip “BTW It is not easy to find out what MATM means.”

    I apologize but the change in fonts from my original document changed the micro symbol into a “m”.

    • Thanks Jim,
      Your conversation with Ferdinand Engelbeen is very interesting. Ferdinand is a keen proponent of the view that the historic rise in atmospheric carbon dioxide is due to fossil fuel combustion. He uses mass balance considerations and carbon isotope variations, particularly the increase in atmospheric light fraction C12, to support his analysis. I would like with your help to explore the issue of carbon isotope fractionation.

      I understand how C12 becomes concentrated in biomass by the preferential RuBP uptake of the lighter carbon isotope during photosynthesis. Fossil fuel combustion, for example coal which is indisputably biological in origin, returns light carbon to the atmosphere and this change in C12 atmospheric abundance can be measured. This is clearly an example of chemical isotopic fractionation, both in initial uptake into the lignin and subsequent release by combustion of the fossil carbon.

      I also understand how the physical phase change of a material can alter the atomic isotope ratio of its constituent molecules. For example the change in isotope ratio of oxygen in water by repeated cycling of evaporation and precipitation on land has been used to track the influx of the West African Monsoon away from the Atlantic Ocean. Fresh water is more enriched in light fraction O16 by the repeated atmospheric cycling that occurs the further north the monsoon reaches into the modern Sahel and also historically into the central Sahara.

      The first question I have is does the release of dissolved carbon dioxide from the ocean into the atmosphere produce carbon isotope fractionation? I suspect that the answer to this question is no. I expect the explanation is that a change of state required for isotopic fractionation to occur. Liquid water to atmospheric vapour in the case of oxygen isotope fractionation of H2O, and chemical changes during photosynthesis are both examples of changes of state and these changes are required for isotope fractionation. The movement of gas from the ocean to the atmosphere does not involve a phase change and so no isotope fractionation of the carbon dioxide gas can result from this liberation of gas from one reservoir to another.

      My second question addresses the process of calcium carbonate precipitation from seawater solution. Does this process, which clearly involves a change of state, produce carbon isotope fractionation? I was particularly interested to learn that the biochemical process of aragonite formation in coccolithophores is not a closed system and that dissolved carbon dioxide gas can be released into the seawater surrounding the algal cell. In addition to this biological source of marine carbon dioxide we also have the inorganic precipitation mentioned by RWturner (March 25, 2015 at 11:31 am)

      In fact, aragonite, the most easily dissolved polymorph of CaCO3, is still precipitating without biologic forcing within shallow seawater forming oolites on shoals around the Bahamas, Persian Gulf, and northwest Australia, as well as in whitings in the Caribbean and Persian Gulf.

      The carbon dioxide released by this chemical process of warm water precipitation, because it does not occur within a living organism, is more readily transmitted directly into the atmosphere, particularly in the shallow water beach swash zone during wave agitated oolite grain formation.

      I suspect that the marine process of calcium carbonate precipitation from bicarbonate solution produces isotopic fractionation of carbon. The heavier C13 containing anions are preferentially crystallised resulting in an increase in light fraction C12 anions which convert to the dissolved gas fraction in the seawater. This C12 enriched carbon dioxide gas is then released from the ocean into the atmosphere and forms a natural source of light fraction C12 gas in addition to the recognised industrial source from fossil fuel combustion.

      Comments and corrections are welcome from all.

      • Philip,

        Some reference about the isotopic changes for CO2 at the seawater-air border:
        http://dge.stanford.edu/SCOPE/SCOPE_16/SCOPE_16_1.5.05_Siegenthaler_249-257.pdf
        What I understand is that there is a kinetic component in the fractionation: the lighter fractions are faster moving in and out, giving a lighter ratio in both directions after passing the air/water border. The average change in the atmosphere from ocean to air and back to ocean is in the order of – 8 per mil (-10 per mil water-air, +2 per mil remaining in air after the air-water passage). As most exchanges are seasonal between the ocean surface and the atmosphere and back and the ocean surface is between +1 and +5 per mil, the historical average of -6.4 +/- 0.2 per mil in the atmosphere is probably entirely from the ocean – atmosphere exchanges, even without unbalance between the two. Atmosphere – vegetation exchanges were probably more or less in equilibrium too, which had little influence on the 13C/12C balance, until the start of the industrial revolution.
        In the previous message, I referenced Böhm e.a. about coralline sponges. It seems that the aragonite skeleton of these sponges quite exactly reflects the average 13C/12C ratio in the surrounding seawater, although there is a lot of fractionation between the different carbon forms.

        So, quite surprising that the isotopes of CO2 as gas do fractionate between solution and atmosphere, while there is little fractionation when transformed from solution into solid…

      • @ Philip,

        I am not well enough versed in isotopic analyses to decipher Ferdinand’s mass balance considerations and carbon isotope variations on a grand scale. But I can look at studies on a case by case and look at confounding factors. For now I can not critically comment on his analyses other than to share my concerns that there is to much local and spatial variation I can’t trust assumptions that ocean delta 13C is currently -10, or whatever figure each study evokes.

        There certainly are various degrees of fractionation.Photosynthesis prefers 13C but C3 versus C4 photosynthesis fractionate differently because C4 plants involve extra steps before fixing CO2. I don’t know the details but I assume that marine plankton will cause different degrees of fractionation especially between bacterial, algal and macro-algal groups Ecologists have been using differences delta 13C to look at food webs so that different organism store a wide variety of delta 13C. Penguin biologist find della13C has changed considerably over the last few hundred years in eggshells. They infer its a change prey items that currently exhibit -18 to -30 delta13C.

        Examination of Antarctic sea ice shows large differences in delta13C between sites 100 meters apart in a given location and between locations 1000 meters apart.

        But Ferdinand’s perspective intrigues me nonetheless so I am just about to read his study and delving into as much literature as I can over the next few weeks, so I can respond to such arguments with more knowledge.

        regards coccolihtophore leakage of CO2 , I think if greater importance is the pumping of alkalinity to depth and creating an ocean surface layers that is more sensitive to DIC and thus a more variable pH. Calcium carbonate shell makers like coccolithophores, foraminifera and pteropods pump significant amounts alkalinity to various depths.

        Phillip send me your email address to jsteele [at] sfsu.edu and I’ll email any thoughts that might be of interest to you.

      • Ferdinand Engelbeen: March 28, 2015 at 9:55 am (below)

        So, quite surprising that the isotopes of CO2 as gas do fractionate between solution and atmosphere, while there is little fractionation when transformed from solution into solid…

        Thanks Ferdinand:
        I agree, this is surprising, clearly nothing in this subject can be deduced, it seems that everything must be determined by measurement and experiment. Having said that I will continue with deduction for a little longer. While I can understand why photosynthesis favours the lighter C12, as the reduction of oxidised carbon to organic carbon is essentially equivalent to an endothermic reaction, what I am keen to establish is how the inorganic precipitation process operates. This should be a relatively simple experiment to perform, as it involves the expulsion of carbon dioxide gas created by the process of calcium carbonate precipitation from bicarbonate solution. A comparison of the C12/C13 ratio in the inorganic crystal carbonate compared with the same ratio in the expelled carbon dioxide gas should easily show if, in the inorganic realm, no carbon isotope fractionation occurs.
        Anyone know who did this experiment?

      • Found a readable lecture about 13C/12C fractionation, which says that the fractionation in seawater is mainly between the dissolved CO2 and bicarbonate formation, thus not between CO2 gas and solution…

        See:
        http://www.whoi.edu/science/MCG/dept/education/MOG_course_djr_tie/MORG%202005%20stable%20carbon%20isotopes%203-01-05.pdf
        Because dissolved CO2 is less than 1% in seawater and bicarbonate is 90% (carbonate 9%), it makes not much difference for the isotopic shift.
        Another view is here for oxygen and carbon isotopes. which confirms that there is little fractionation between dissolved CO2 (bicarbonate?) and solid carbonate:
        http://www2.ocean.washington.edu/oc540/lec02-19/

        Seems that there still is a lot of confusion where exact the fractionation occurs…

      • Ferdinand Engelbeen: March 29, 2015 at 10:05 am

        the fractionation in seawater is mainly between the dissolved CO2 and bicarbonate formation, thus not between CO2 gas and solution…
        Seems that there still is a lot of confusion where exact the fractionation occurs…

        Ferdinand,
        Thanks for doing such good spade work.
        I am reassured by this. It appears that my assumption that a change of state is a prerequisite for fractionation is correct. The free carbon dioxide whether in the atmosphere or in the ocean is still a gas. It would be a curious thing if the water boundary surface tension acted as a membrane filter capable of producing isotopic fractionation.
        I can see how the process of chemical combination of gas with water to produce carbonic acid could result in carbon isotope fractionation, however I still think that the process of carbonate crystallisation needs to be eliminated as a possible source of fractionation.
        Because calcium bicarbonate can only exist in solution and not as a crystal, I propose that the following simple experiment be performed:-
        Take a solution of sodium bicarbonate of known C12/C13 isotopic composition.
        Mix this with a solution of calcium chloride of appropriate concentration.
        Evaporate the mixed solution to dryness and recover the carbon dioxide gas expelled during the process of calcium carbonate precipitation.
        Measure the isotopic ratio of the carbon in the expelled gas.
        Measure the isotopic ratio of the carbon in the carbonate crystals.
        This experiment will establish if any change in carbon isotope abundance takes place during calcium carbonate crystallization.
        So my question to the wider world still stands. Has anyone done this experiment?

  39. During the Mid Devonian period..around 380 million years ago…atmospheric CO2 was around 4000ppm, somewhat higher than today.
    http://www.gly.uga.edu/railsback/Papers/CoxRailsbackGordon.pdf

    That didn’t stop marine creatures from flourishing and from building large carbonate reef systems in what are now China, Canada and the US, Europe and Australia.
    eg http://dmpbookshop.eruditetechnologies.com.au/product/devonian-reef-complexes-of-the-canning-basin-western-australia-geographical-product-n98q.do

    That marine critters were seemingly happy with conditions at the time suggests that there is significant pH buffering in the oceans and that atmospheric CO2 doesn’t lead to “acidification”

    And by the end of the Devonian it seems there wasn’t enough CO2 to go around….

    http://paleobiology.si.edu/geotime/main/devonian4.html

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