You can look at it as a perturbation of the carbonate buffering system. Basically by increasing the concentration of CO2 you are shifting the equilibrium of the carbonate system in such a way that, in the end, the concentration of HCO3(-) and H(+) ions increase while the CO3(2-) concentration goes down. The increase in H+ ions is what causes the pH to drop, i.e. acidification, although the seawater will still have a pH above 7 so will not technically be “acid”. The decrease in CO3(2-) is what leads to the decrease in Aragonite and Calcite saturation and this is the problem for organisms that use these minerals for calcification (eg corals, pteropods, molluscs, forams, etc).

In simple chemical terms (taken from Andrew Dickson) it plays out as follows:

When CO2 dissolves in seawater it combines with water to form hydrogen (H+) and bicarbonate (HCO3-) ions:

CO2 + H2O -> H(+) + HCO3(-)

Some of the hydrogen ions combine with carbonate (CO3(2-)) ions to form additional bicarbonate ions resulting in a decrease in the former and an increase in the latter:

H(+) + CO3(2-) -> HCO3(-)

Thus, the net effect when is added to seawater is for the concentrations of H+, CO2, and HCO3- to increase, and the concentration of CO32- to decrease. —A. Dickson

As to why this will not be buffered or absorbed by photosynthesis and an increase in photosynthetic organisms – a certain amount of it will be but the vast majority will not. CO2 is not the rate limiting chemical for most photosynthetic organisms – eg phytoplankton is primarily limited by iron availability, plus during the dark phase of photosynthesis there is nett CO2 production. There is some evidence that green macro-algae (eg sea grass) might benefit from the CO2 increase but that might be another stress on corals and shift the competitive balance on many reefs (particularly those that are under stress from other sources such as increased nutrients from run-off).

A very good resource is:

http://ocean-acidification.net/

which is a clearing house for information and has a lot of resources available for both lay and scientific audiences.

Hi Akbar, as you can see David has explained in a very detailed way the direct effects of increasing CO2 on the existing equilibrium, and the imbalance of ionic and non-ionic chemical species with the consequent alteration of pH. But I want to point out another essential aspect of this CO2-induced alterations and why the buffering effect can’t deal with them: the rate of change.

What does it mean? Well, when we talk about the calcium carbonate compensation system we are describing a process that has developed over historical time. A system that can deal with natural variation of CO2 and usually it means “slow processes” (it is quite difficult to quantify).

The amount of CO2 itself doesn’t matter, what is important is the time-frame. Currently, we are observing a constant increase in the production of carbon dioxide caused by human activities, such as the increasing combustion of fossil fuels, and since the industrial revolution CO2 concentration has steadily increased.

A marked increase in carbon dioxide occurred during the Paleocene-Eocene Thermal Maximum (PETM, about 56 million years ago). During which were recorded levels of carbon dioxide similar to the current ones; but as I said, the problem is not the level itself but the rate of change preceding the maximum. In fact, the current rate of change is about 10 times higher than the rate preceding the PETM. A situation that the calcium carbonate compensation system is unlikely to balance.

I suggest visiting this very nice website http://climate.nasa.gov/ that shows the current increase in CO2, temperature, etc. just to have an idea of the real increasing concentration of carbon dioxide in the last century.

http://climate.nasa.gov/

Hi Akbar,

The effect of photosynthetic organisms on carbon in the ocean is significant but as David has mentioned it's limited currently by the availability of nutrients such as phosphate and iron.  So one way to increase the uptake of carbon via photosynthesis would require an increase in these nutrients as well.  However, It's looking likely that ocean acidification will have a negative effect on some phytoplankton, particularly those which produce calcium carbonate shells which are affected by the changing chemistry. That could potentially reduce the role which biology plays to removes carbon from the surface ocean.

Further to Luca's point about the rate of CO2 increase, Honish et al. (2012) is a good review on ocean acidification in the past.  Figure 3 in that paper shows the different responses of pH and carbonate to varying rates of atmospheric CO2 increase in an Earth System model.  

Honisch et al. (2012) The geological record of ocean acidification.  Science. 335 (6072), pp. 1058 - 1063http://www.sciencemag.org/content/335/6072/1058.abstract

You are correct. The acidification problem may be occurring in the coastal regions, it won't occur in the open ocean, the PH is always higher in the ocean due to higher salt content. We can try to test the same when we going for cruise. Thank you.

David, Luca, and Jamie all added some very nice responses.  There are a couple basic things I think still might not be clear that are important to help understand acidification.  People think pH 7 is the definition of neutral, and that is false. 7 is the 1/2 the pKw of pure water at 25˚ C (basically the pKa of water). The pKw (the -log of the dissociation constant of water) depends on temperature, being higher at lower temperature (because water dissociates less), and lower at higher temperature. At 4˚ C, a pH of 7 is slightly acidic, for pure water. In contrast, at 40˚ C, a pH of 7 is slightly basic, for pure water. I emphasise "for pure water" because "acidification" refers to the direction of change from the previous value of the chemical system.  The dissociation constant for water also depends on ionic strength, so it is not the same in seawater as in pure water. Seawater naturally has a higher pH than the equilibrium constant of water, and the main buffers, besides water itself, are the carbonate system (bicarbonate HCO3- carbonate HCO3(2-)), with borate as a distant second.

Even under most naturally acidified conditions (e.g., upwelling of waters rich in CO2 on the eastern sides of the Pacific Ocean, e.g., in California, Oregon, Chile, and Perú), and in predictions for human-induced acidification, seawater won't be acidic with respect to the pKa of water.  But it is appropriate to call these changes "acidification" because the seawater is becoming more acid/less basic.  In some cases surface waters will become corrosive to aragonite.

A lot of right-wing science deniers (especially in the USA) claim that "ocean acidification" is fake or misnamed because the pH never will go below 7, creating a lot of confusion.  I'd be interested to see how long they would volunteer to experience a pH drop in their blood of similar magnitude to that experienced in the ocean due to rising CO2. Human blood pH is normally in the range of 7.3-7.5 (it's usually even more precisely regulated).  At 37˚ C, that is "basic" if you compare it to water.  Nevertheless, if the blood of you or I or any human drops to 7.2 for an extended period, we would be facing a critical condition with the medical terminology "acidosis" (even though the blood pH is greater than 7).  So the use of the term "acidification" for the pH drop of seawater is consistent with the much older physiological terminology.

In the ocean, there is a great diversity of life. Some organisms might have a physiological benefit, some would not be affected, and some (like many corals) will be severely negatively affect.  Some may also have the capacity for evolutionary adaptation, while others may not.  These differential responses can cause ecosystems to change in surface waters.  In deeper waters, the saturation horizons for aragonite and calcite become less deep, so organisms that calcify (a lot of animals) will have much more restricted vertical distributions.  Not only that, the "ballast hypothesis" suggests that the sinking of organic carbon from the surface to the deep depends on organic matter being weighted by inorganic matter (calcite). Ocean acidification will cause calcite to dissolve at lower depths (the solubility of calcite and aragonite depend on pH, temperature, and pressure), and this might mean less organic matter sinks deeply.

Thank you for all of your explanation :)

Now i understand how CO2 concentration and rate of change can shift the equilibrium, nutrient-dependent carbon uptake by photosynthesis, basic concept of "neutral" pH, aragonite and calcite solubility, and terminology of acidification it self.

Terima kasih! :) 

Hello Akbar thanks for raising this important question.  Yet please continue to raise it, as this forum has not yet reached the full disclosure necessary to answer fully or candidly.  Moreover, in this academic forum one of your respondents wrote an ad hominem that "

A lot of right-wing science deniers (especially in the USA) claim that "ocean acidification" is fake or misnamed because the pH never will go below 7, creating a lot of confusion.  '  "

I am such a person by that standard but moreover I directly research in ocean records and reconsciliation with carbonate chemistry.  I have been working on a paper and other research that paints a somewhat different picture of the relations between carbonate ocean chemistry, buffering, data, and ocean pH described here, although I am on many of their same pages.  These researchers appear to be collectively asserting that the impact to aragonite saturation conditions in the ocean cannot be captured by pH measurements.

some thoughts

Ocean pH continues to be promoted as if a potentiometric pH meter cannot be trusted. Rather only expensive Rube Goldberg contraptions involving spectrometric machines linked with old fashioned indicator dyes are supported by one and all in the marine sciences community. Meanwhile the rest of the world, from health sciences to geosciences continue to effectively deploy the highly reliable pH meter. My own work based on such meters shows that ocean pH is highly and significantly correlated to the Pacific Decadal Oscillation and even to other aspects of the hydrosphere. Why does everyone in the scientific community continue to whistle past this graveyard? How long do you all think this expensive and anxiety inducing myth can persist? When the myth is blown, what public consequences do you all think you are immune to?

Many are reading this string. Some are following up to read a related paper I authored but which was never published. One reason given by a journal for not publishing was that "the oceans are not buffered solutions". I think this statement speaks volumes for the abysmal state of marine sciences today.

It's bad enough that marine scientists don't believe in the validity of data or the value of a calomel electrode pH meter, or even of the foundational Standard Hydrogen Electrode, but rather favor opaque and irreproducible simulations.

Luis Pomar I didn't notice your paradoxes before. I think they are based on some not factual assumptions.

Regarding paradox #1 about the 10x higher CO2: This will not cause the oceans to get a pH that is below 7 so we cannot say they are acidic. If the planet has 10x higher CO2 in the atmosphere the solubility of CaCO3 will increase and pH in the oceans will be lower. However, once this equilibrium is established we will still be able to precipate CaCO3 from the saturated seawater in conditions there high photosynthesis activity drive pH up.

Regarding paradox #2: Biomass can be higher in higher trophic levels. It just require that the predater live much longer than the prey. A classic example is greena algea and zooplankton in oligotrophic lakes there the zooplankton biomass is often higher than the algae biomass.

Good question and informative answers

Following

Following.

Why is Henry's Law always thrown out the window when scientists discuss ocean acidification? 10X more CO2 says Dr. Anderson? Is that WITH increased global temperature or WITHOUT? Does Temperature have anything to do with the solubility of CO2 in the ocean or doesn't it? Can equilibrium modeling with codes such as PHREEQC capture the essentials, or must all practitioners of ocean science use unvalidated SeaCarb models and their cousins, largely based on throwing out almost the entire world's history of ocean pH measurements? The consensus police don't allow such a discussion in an actual peer review paper. Hi Police.

Mike Wallace, Indeed, solubility of CO2 in the Seas and Henry's law for CO2 is temperature dependant. My comments on the 10x higher CO2 are qualitatively and the same regardless if we consider the same temperature or the several degrees temperature increase of Ocean surface waters that would result from actually increasing the atmospheric CO2-concentration 10-fold.

Thanks Henrik, that makes sense and fits with what I've read lately concerning some work by Ridd and others. If I understand then, much of the calcifying marine life is very robust and durable, and a little bit of added hydronium ions in the water environment (even if it were possible to increase them from atmospheric forcing, and even if that overcame buffering) is not sufficient to cause those organisms harm. I didn't intend to come on so negatively, and thanks again. I hope more will read your concerns and mine and engage.

We are fortunate that the oceans are very well buffered and adding CO2 thus only change pH relatively little. In order to quantify such changes it appears crazy not to use pH electrodes as you mention.

Many organisms in the sea are robust to pH changes but key groups such as the coral reef building polyps and their algae symbiotes unfortunately are harmed by minor changes in pH then it coincide with higher temperatures.

For what it is worth, I have continued to survey the 80 years (~2 million records) of ocean pH electrode readings that somehow for some reason have been eliminated from contemporary marine science discourse. Here is a link to my recent post: http://www.abeqas.com/connections-between-the-thermocline-and-ocean-ph/

It's amazing I think, that these omitted records are the only ocean pH records that confirm consistency with the THERMOCLINE. It certainly would be inconvenient for marine scientists to explain why the ocean pH tracks with the thermocline while they simultaneously assert that the partial pressure of CO2 is the primary driver of pH. The nightmare continues.

Have you considered the influence of weathering of rocks, like feldspars or peridotite minerals. Not only weathering of CaCO3 is on the table.

I am looking for furtherr information about the influence of the weathering reactions.

My textbook is Stephen Marschak: Earth, portrait of a planet, contains introductory information.

Lars Gunnar Sillén is said to have had thoughts about dolomite formation in sea-water and its influence on pH, but I have no information, but intend to go further with the question.

Sounds like a worthy approach. I will point you to a modeling exercise I conducted a few years ago using the geochemical speciation code PHREEQC, which appears to support that weathering is paramount. There are papers I"m finding which relate coral reef paleohistory with ocean pH via a boron isotopic fractionation relation. The authors have related that to the Pacific Decadal Oscillation (PDO). I'm also finding a likely significant correlation between pH and oxygen istotope fractionation simply by reading literature! One cannot seriously look and NOT find the important and consistent correlations which challenge the myth of OA.

Hi Akbar,

Ocean acidification occurs when pH-levels of the ocean decrease due to an increase of CO2 in the atmosphere. The increase in CO2 need not be rapid, nor man made. CO2 rose during the PETM (Paleocene-Eocene Thermal Maximum) much more slowly than today and from an unknown natural source but the resulting fall in pH dissolved the calcareous sediments causing the lysocline, aka snow line below which carbonate sediments do not form, to shoal.

The ocean does not need to be acidic i.e. pH less than 7, for calcium carbonate to dissolve. It will dissolve if the water pressure is great enough. Thus there is a depth in the ocean, lysocline/CCD (calcium carbonate depth) below which calcareous sediments are not found because of the pressure there. This depth also depends on the pH of the sea water. The lower the pH the shallower the CCD.

Buffering does not stop pH falling when acid is added. It prevents it falling as much as one would expect.

The chemical reactions in the ocean are:

CO2 + H2O H2CO3 H+ + CO3- 2H+ + CO32- Equ. 1.

So you might expect that there would be two moles of H+ formed for every mole of CO2 dissolved. But because these are equilibrium reactions, less and less H2CO3 is disassociated as the pH falls (H+ increases). This effect is called buffering, because the HCO3 and CO3 ions buffer (absorb) the H+ ions. The

amount of buffering is called the alkalinity and is equal to [HCO3-] + 2 [CO32-].

Cyanobacteria and algae perform photosynthesis which can be written as:

CO2 + H2O -> CH2O + O2 Eqn. 2

When this happens in sea water, Equ 1 is driven to the left by the loss of dissolved CO2 and pH increases. When respiration happens Eqn. 2 is driven to the left and Equ. 1 to the right causing pH to fall.

What you have not mentioned is the formation of the carbonate sediments. They are formed from the shells of phytoplankton called coccolithophores. That reaction can be written as:

Ca2+ + CO32- CaCO3 Equ. 3.

This reaction causes Equ. 1 to move to the right, drawing more CO2 out of the atmosphere and increasing H+ thus lowering pH in the surface waters. Alkalinity will also fall as there are less carbonate ions to act as an acidic buffer.

Coccoliths which sink in deep water below the CCD will dissolve. Equ. 3 will move to the left and Equ. 2 to the left increasing alkalinity and pH.

Hope this helps, Alastair.

There are many questions:

1: Sea water contains calcium ions and hydrocarbonate ions, but the hydrocarbonate level is lower than implicated by the CO2 pressure of the atmosphere (it corresponds to 90 ppm CO2, much lower than historic CO2 ppm levels (180-300 ppm) during last glaciations). Then pH would be something about 5,0 approximately, rainwater is acid, but today even more acid duie to sulphur pollution.

2: The equilibrium H2CO3 (in solution) level would be 0,07 mM at pH = 8,2 (approximately). Sea water would then absorb carbon dioxide quickly. The titration curves of sea water would the show a slight pH decrase for the addition of acid.

3: Weathering reactions of olivine, wollastonite, plagioclase etc point to the formation of orthosilicic acid H4SiO4, hydrocarbonate and hydroxide ions, i.e. a slight alkaline buffered system as in sea water. The same with the weathering of calcium carbonate.

4: The whole process is driven through the subduction of abyssal earth crust and correponding volcanic activity on a geological time scale. Still it is interesting to study what the quickly raised atmospheric CO2 level will influence the pH, but the bulk of the oceans must still be more influenced by the accumulated geologic influence, although surface waters are changed. Occuring stirring of the bulk of the oceans will in the long run moderate the CO2 influence on the pH close to the surface, when the absorbed CO2 is mixed with bottom waters.

My conclusion: The pH and carbonate content of sea water is more controlled by weathering reactions and not by the absorption of atmospheric CO2. Absorption of atmospheric CO2 will of course influence the seawater pH, but the titration curves still hint that the lowering will be moderate.

H2CO3 concentration at pH 8,2 is very low, because pH is above the pKa 6,3 of H2CO3/HCO3- , so the equilibrium level of CO2 is even lower. (red line in the diagram)

Awesome answer Dr. Bruno, in my constant learning curve view. It makes sense to me and for what it's worth, I've exercised a standard sea water problem from PHREEQC simulator to explore how pH might evolve over different relatively proportions of atmospheric CO2.. there is hardly any movement due to the strong buffering. It also seems that marine scientists ignore the temperature connections to pH.. they at least are correlated across the oceans when glass electrode measurements are used and show the thermoclines well.

Akbar, I think it is extraordinary that your posted question and the few answers it has received now accounts for over 14,000 reads. Perhaps that is some kind of record. I would like to propose that people who have read this post consider joing the brewing debate on more public platforms. I can contribute by drawing attention to this link: http://www.abeqas.com/is-the-university-of-california-retreating-from-assertions-of-ocean-acidification/

It is self explanatory but also includes important comments by a NOAA director to me on the nature of the missing global ocean pH data. If that data were not omitted in the first place, none of us would be having this conversation. In any case, lets all 14,000 of us move towards more transparent venues. If the University of California and important scientific leaders within NOAA are beginning to take baby steps back towards accountable and reproducible science, it might be a big deal.

Some great answers=spot on. It is a simplistic approach with water I should caution (it is mineral ocean water containing bicarbonate and phosphate-both physiologic buffers-and various cycles that influence it's composition). We can measure the decrease in pH at ocean surfaces but lots going on simultaneously changing on different time scales altering the equilibrium ( like carbon-silicate cycle and hydrological cycles so bicarbonate is leaching from land to sea, etc). The ocean can theoretically absorb/buffer the extra carbon just on time scales to slow. Melting ice alters salinity changing currents, ad infinitum. So it's overlapping equations shifts in different parts and on different time scales-and it's all being overwhelmed by human activities. I don't want this to read as discounting the impact. Time scales is important I guess is my point. This issue of "time" also relates to life-in life (really depends on generation time) generally can't evolve fast enough to mitigate the climate change. This is where I suggest using CRISPR-cas to genetically modify life in ways that will assist their mitigating this rapid climate change. Coral reefs ecosystems seem a perfect place to investigate a possible use. What surprises is the most recent paper on Earth's biomass distribution as in Gigatons of carbon. In oceans It's a reverse pyramid compared to terrestrial life and represents a much smaller fraction of earth life biomass of carbon than I would have expected-given the huge volume and mass of the oceans. Just 6 GT of the approx 550 Gt, I really expected marine life to have a much larger biomass and thus impact on fast phase of carbon cycle (land plants dominate according to this paper). I thought the idea of iron seeding to stimulate phytoplankton to increase biomass worthy of a try but now I don't see it. We have diminishing returns in trying to address climate change because the sensitivity of the equilibrium becomes more sensitive to human influence as the extinction event we've been in for hundreds of thousands of years is lowering life's biomass and ability to sequester carbon in life itself. The last 10,000 years extinction has increased and now with climate change that exacerbates even a faster extinction rate. We are fighting diminishing returns and just human growth displaces wild species (lots of papers demonstrate that, as human biomass grows, the amount of solar energy and net primary productivity available for use by other species shrinks, ultimately shrinking the amount of the world’s biomass accounted for by those non-human species.) You do see that impact in this biomass paper with humans and domesticated animals surpassing that of wild species. We've altered the carbon cycle, nitrogen cycle, hydrological cycle, phosphorus to, and then our behaviors produced extinction events and changes in ecosystems. It's a perfect storm coming together on all fronts it seems.

I see people already explained about the buffering capacity very well. About the cyanobacteria roles, it is one of bacteria that can produce EPS, which is important as organic ligand to enhance iron bioavailability and acts as biofilm to aggregate the decay organisms to make it as nutrients for photosyntesis. As we know, iron bioavailability is very low, thus need organic ligand to enhance its bioavailability. This iron bioavailability then can promote algal blooms because it is important factor for photosynthesis.

Syarifatun some have explained it better than others. I continue to learn including from your post and Arthur Chandler Beall but I'd be interested to know how Arthur measures pH in his laboratory. Does he use a glass electrode pH meter. If so, he should be aware that those have been banned from use in ocean sciences as per Doney, Feely, Sabine, Gattuso, and others. If the meter records were not banned, then we all wouldn't be having this conversation.

Hi Fredrik Bruno ,

You wrote "Sea water contains calcium ions and hydrogencarbonate ions, but the hydrogencarbonate level is lower than implicated by the CO2 pressure of the atmosphere (it corresponds to 90 ppm CO2, much lower than historic CO2 ppm levels (180-300 ppm) during last glaciations)."

Do you have a reference that shows the calculations involved? I am very interested since I think I have an explanation.

I use my home bible: Marcel Pourbaix: Atlas of Electrochemical equilibria. Pergamon Press 1974. The book contains information about water-based systems at 25C for all essential elements. You can find/buy copies on the internet. The book is more than 40 years old, but still valid. Above this, its normal thermochemistry calculations and a standard analysis for sea water.

Rain will have a pH about 4-5, so the pH 8,3 (crossing of a green and red line in my earlier diagram) of sea water should be caused by the dissolution of carbonate, probably from old foraminofera/plancton. Normally only the upper 100 m is affected by sea waves, and the exchange with deep water (cold water sinking outside Greenland) is a much more slower process. I am very suspicious about the saying that melt water from Greenland (300 gigatons a year, thats a promille or less of the total ice cap !) should float out on the surface of the Atlantic and hinder/prohibit/delay the sinking process of the AMOC overturning. The proportions between melt water and the extent are of the sinking taking place are disproportionate.

For dry systems at room to elevated temperatures, look for a compilation of Otmar Knacke and Ihsan Barin, it is out of print, but should be available at technical university libraries (KTHB in Stockholm).

Fredrik Bruno, Like Alastair Bain McDonald I am interested in the source for the 90 ppm CO2 you mention ".. but the hydrocarbonate level is lower than implicated by the CO2 pressure of the atmosphere (it corresponds to 90 ppm CO2, ..".

Exactly where do you find this and are you referring to surface waters or the deep sea?

The bio-sequestration of CO2 by algae and cyanobacteria, can be effective but just for short time, and we observe the eutrophication process. If this process is intensive, it has very negative for water. The light transmittance in the depths of the water is reduced, so the all biomass of algae in the aphotic zone dies and its decomposition processes begin, there is an intensive secondary release of CO2. Cyanobacterial toxins along with anaerobic conditions kill a huge amount of animal organisms, which also begin to decompose and release another portion of CO2.

Modern modeling methods are now available, from the analysis of hyperspectral images from monitoring satellites such as Sentinel and Landsat. You can measure these phenomena and make predictive models. I am going into these methods for surface waters.

Developing an effective buffer for seawater is a very big undertaking, maybe microorganisms can be usefull in reducing. Professionally developed mixtures of biopreparations can stop the eutrophication processes for several seasons in case of lakes and other inland water bodies.

The introduction of cladocera biomass to the water, can properly reduce the biomass of algae, may also prevent intensive eutrophication processes for a short time during larger blooms.

Question of Mr Andersen: Look for Marcel Pourbaix: Atlas of Electrochemical Equilibria, Pergamon Press or NACE (second edition). It can be found on the internet, although it is ca 50 years old,´. Contains thermodynamics for aqueous solutions, and the equilibrium values between CO2 in air and CO2 dissolved can be calculated from the chapter; Carbon. The carbon or hydrocarbonate can be found in various sources

Answer to Robert Mazur: I thought most of the dead plancton sunk to the bottom, the so called biological pump, so that the carbon debris was buried in the sediments on the ocean floor.

The pH around 8,3 is the outcome of the reaction between carbonate (from foraminofera and coccolithes) and dissolved CO2.

Robert Mazur

The idea of sequestering CO2 by fertilisation did not work because the organic carbon which sank to the ocean floor was oxidised back to aqueous CO2 by oxygen rich water originating in the polar regions. The fall in pH would also have caused carbonate sediments to erode increasing the dissolved inorganic carbon (DIC) in the ocean. So rather than acting as a sink for carbon it acted as a source.

Admit that the figures of carbon in abyss sediment samples were lower than I expected. Carbonate shells are dissolved due to the pressure, so they are not involved. I can't quantify the figures, whether they are essential or not.

http://su.diva-portal.org/smash/get/diva2:1350641/FULLTEXT01.pdf

Model analysis of ocean carbon storage and transport across climate states Author Malin Ödalen Stockholm University

Fredrik, Thanks for that excellent dissertation study. I've combed through briefly myself and it seems to make a lot of sense. Except regarding the Atlantic Meridional Overturning Circulation (AMOC). I recommend that any reconsider the validity of the AMOC. The AMOC researchers see what they want to see, much like the ocean acidification researchers, in my estimation. I again appreciate the link to the paper by Malin Odalen which you just provided, and I'm happy to recognize that it makes zero references to "ocean acidification".

Author of the thesis:

'[email protected]'

About AMOC:

Leon Chafik, researcher at the same institution

Thanks. The AMOC appears to have left out the Canary Current, if I'm not mistaken. That means the mass and energy flows are not balanced. The Gulf stream demonstrates incredible northward flows along surface but the only counter direction appears to be a density dependent trickle across the ocean floor. By the way, ocean upwelling and downwelling are faithfully captured by the 2 million disregarded glass electrode pH meter readings of the bulk of the 20th century. Sorry about bringing that up again, it seems important.

If the temperature difference between Arctic and tropics decreases, it is quite natural that the AMOC loses speed. AMOC transports heat northwards, and when the temperature gradient slackens, of course tha AMOC must slow down. But climate change temperature rise must be greater/bigger? , so we will get rising temperatures in Sweden anyhow, but more moderate. That's ordinary control theory. But papers are scaring the public with a new ice age.

Mike Wallace

You wrote "The AMOC researchers see what they want to see, ...". Interestingly the authors of the AMOC theory have just admitted that! See 'The Rise and Fall of the “Atlantic Multidecadal Oscillation"' at: http://www.realclimate.org/index.php/archives/2021/03/the-rise-and-fall-of-the-atlantic-multidecadal-oscillation/ by one of the original authors of the first AMOC paper.

However, that is not true for ocean acidification. Atmospheric CO2 has now risen by almost 50% despite the oceans acting as a sink. They will continue to do that until the atmospheric pCO2 and the ocean fCO2 are equal. CO2 is acidic when dissolved in water and although the sea is a buffer solution that does not prevent the pH falling; it only means that it falls less quickly than it would if the ocean was not a buffered solution.

Thanks Alastair! I should note that Mann was writing about the AMO and my comment was about the AMOC. Those are confusing in names but refer to different topics. I have also recently written two posts about the AMOC, at abeqas.com (my own site). I appreciate your views on CO2 but until someone comes up with a valid reason to dismiss them, I believe in the 2 million omitted glass electrode pH meter readings. That century - long record doesn't show a hint of acidification. There are many comments above which also speak to the "vital effect" of phytoplankton and more, which seem to have the capacity to consume as much anthropogenic CO2 as we could ever hope to deliver to them. By the way if I'm not mistaken, there is no isotopic means to differentiate anthro CO2 from fossil fuel from natural CO2. It's a detour for now but perhaps worthy of discussion also. Anyway I appreciate your insights Alastair even if we aren't on all of the same pages yet and I look forward to more discussion.

Mike,

just after postng my last message I began having doubts that increasing atmospheric CO2 would lower ocean pH. So I will be investigating your pH meter readings, and the 'vital effect' of phytoplankton, a concept that I have come across elswhere recently.

PS, I have downloaded a PDF version of the book, Pourbaix, recommended by Fredrik Bruno but I cannot find where it says that measurements and calculations of carbonate chemistry disagree.

PPS you may find this paper interesting: Article Evolution of natural and anthropogenic fluxes of atmospheric...

Sounds great! I am a big fan of Pourbaix diagrams but as always I have much to learn. I've used PHREEQ-C to model ocean pH, for what that is worth. But as with other models and/or alleged models such as SeaCarb, I think these calculational tools don't account for this "vital" effect. Yes they can be calibrated to lead to an answer that seems to make sense. Perhaps as the science continues to improve, both vital and geochemical processes can be additionally consolidated. Perhaps there are already codes which address, as I've been out of this specific loop for a few years.

By the way if I'm not mistaken, there is no isotopic means to differentiate anthro CO2 from fossil fuel from natural CO2.

The δ13C of carbon from anthropogenic sources as compared to biogenic sources (Suess Effect) has been known since at least the 50s and has been used in a multitude of studies. For example:

Article Carbon isotope composition of Caribbean Sea surface waters: ...

Article The Suess effect: 13Carbon-14Carbon interrelations

Article The 13C Suess effect in scleractinian corals mirror changes ...

Thanks for making the time to debate David. I appreciate and I promise to read your links. Yet we all must try to reconcile Dr. Seuss's claims from over half a century ago with at least some of the current assessments. NOAA states for example that: “Most fossil fuels, like oil and coal, which are ancient plant and animal material, have the same δ13C isotopic fingerprint as other plants.” at https://www.esrl.noaa.gov/gmd/ccgg/isotopes/c13tellsus.html And a

recent article in NATURE Communications states “The effect of CO2

concentration on 13C/12C ratios is currently debated”

https://www.nature.com/articles/s41467-017-02691-x

Perhaps this isotopic Dr. Seuss discussion merits a separate thread?