Ocean Acidification

In the past, I have responded to questions at talks I have given on ocean acidification with an “I don’t know.”  I hadn’t studied the theory and didn’t want to knee-jerk respond with skepticism just because the theory came from people who propounded a number of other theories I knew to be BS.

The theory is that increased atmospheric CO2 will result in increasing amounts of CO2 being dissolved .  That CO2 when in solution with water forms carbonic acid.  And that acidic water can dissolve the shells of shellfish.  They have tested this by dumping acid in sea water and doing so has had a negative effect on shellfish.

This is one of those logic chains that seems logical on its face, and is certainly scientific enough sounding to fool the typical journalist or concerned Hollywood star.  But the chemistry just doesn’t work this way.   This is the simplest explanation I have found, but I will take a shot at summarizing the key problem.

It is helpful to work backwards through this proposition.  First, what is it about acidic water  — actually not acidic, but “more neutral” water, since sea water is alkaline  — that causes harm to the shells of sea critters?   H+ ions in solution from the acid combine with calcium carbonate in the shells, removing mass from the shell and “dissolving” the shall.  When we say an acid “eats” or “etches” something, a similar reaction is occurring between H+ ion and the item being “dissolved”.

So pouring a beaker of acid into a bucket of sea water increases the free H+ ions and hurts the shells.  And if you do exactly that – put acid in seawater in an experiment – I am sure you would get exactly that result.

Now, you may be expecting me to argue that there is a lot of sea water and the net effect of trace CO2 in the atmosphere would not affect the pH much, especially since seawater starts pretty alkaline.  And I probably could argue this, but there is a better argument and I am embarrassed that I never saw it before.

Here is the key:  When CO2 dissolves in water, we are NOT adding acid to the water.  The analog of pouring acid into the water is a false one.  What we are doing is adding CO2 to the water, which combines with water molecules to form carbonic acid.  This is not the same as adding acid to the water, because the H+ ions we are worried about are already there in the water.  We are not adding any more.  In fact, one can argue that increasing the CO2 in the water “soaks up” H+ ions into carbonic acid and by doing so shifts the balance  so that in fact less calcium carbonate will be removed from shells.    As a result, as the link above cites,

As a matter of fact, calcium carbonate dissolves in alkaline seawater (pH 8.2) 15 times faster than in pure water (pH 7.0), so it is silly, meaningless nonsense to focus on pH.

Unsurprisingly, for those familiar with  climate, the chemistry of sea water is really complex and it is not entirely accurate to isolate these chemistries absent other effects, but the net finding is that CO2 induced thinning of sea shells seems to be based on a silly view of chemistry.

Am I missing something?  I am new to this area of the CO2 question, and would welcome feedback.

  • james

    I attempted to post this a couple days ago, but it failed. Too long, I think. I’ve cut it up.

    First, some links. Here are a couple links to reports created by experts in ocean chemistry and ocean acidification
    http://royalsociety.org/document.asp?id=3249

    http://www.ucar.edu/communications/Final_acidification.pdf

    “Warmer temperatures mean less CO2 in the sea” Warmer water does indeed hold less gas of any sort, including CO2. But the oceans are NOT saturated in CO2 and thus warming the water does not lead to significant degassing of CO2 from the oceans. As one comment noted, there is considerable variation in the CO2 content of the ocean surface over the globe. THis is due to temperature to some extent, but more to the downwelling (local sinking) or upwelling of waters. Because deep waters almost always have higher CO2 content (due in part to cooler temperature and mainly to the accumulation of respiratory CO2 caused by the oxidation of organic material by animals, bacteria) areas of upwelling are often sources of CO2 that move from the ocean to the atmosphere. Other areas are sinks for CO2. The net flux is naturally about zero. Just as much CO2 enters the ocean as leaves it due to uptake at the surface and its fixation by phytoplankton, and by degassing of deep water CO2 into the atmosphere. The total flux of carbon as CO2 in and out of the ocean is about 90 billion tonnes of carbon (or 330 billion tonnes of CO2) per year. We (mankind) are releasing about 8+ billion tonnes of C (29 Billion tonnes CO2) into the atmosphere yearly. About 1/3rd of this is absorbed by the oceans = ~10 billion tonnes CO2 per year of anthropogenic CO2 (fossil fuel CO2) into the ocean surface. Note that this is about 1 million tonnes of fossil fuel CO2 per hour is absorbed by the ocean surface.

    Although some may be skeptical that fossil fuel CO2 is actually absorbed by the ocean, it can be measured very accurately by measuring the stable isotopic ratio of the carbon in a water sample. There are 2 abundant stable isotopes of C. These are 12C and 13C. They exist in a very constant ratio in the ocean, which differs considerably from oil, which is far richer in 13C. Using a mass spectrometer to measure the 12C/13C ratio in a seawater sample, and doing just a bit of math, one can determine the amount of fossil fuel (oil) carbon (or carbon dioxide) in the sample. THis is what oceanographers have been doing for a couple decades, and have documented the inventory of fossil carbon in the oceans. Unlike global warming, which is difficult to unambiguously assign a cause of a change in temperature, we KNOW how much fossil fuel CO2 exists in the ocean. Oceanographers also understand the ocean carbonate system very well, and we KNOW (just as we know 2+2=4) that CO2 is increasing in the oceans due to the addition of Fossil Fuel Carbon, and we KNOW it is make the oceans more acidic.

    Some argue (hunter) that the oceans are not getting more acidic and that they are not acidic at all. That is correct, even though hunter is completely missing the point. Ocean acidification is not really the best phrase to describe the change in ocean chemistry that is caused by the increase in total CO2 caused by fossil fuel. The ocean is actually getting less alkaline. But there is nothing magic about alkaline or acidic, except that there are thresholds in its status called the aragonite and calcite saturation state that indicate how easy it is to precipitate calcium carbonate (the 2 major forms created by animals are calcite and aragonite. As the ocean becomes less alkaline or more acidic (choose you own term), the amount of carbonate ions (CO3) is reduced. Carbonate ions are the building blocks for CaCO3, which make up the shells of clams, skeletons of corals, and many other animals and phytoplankton. There is a large body of research now that has shown that as the oceans become less saturated in carbonate ions, calcification is impacted. Corals grow less. If we expose corals to future expected levels of carbonate saturation, some don’t grow. SOme dissolve. That is a major concern.

    TJS states that the oceans are now cooling? Where did this come from. The literature (peer-reviewed literature, not newpapers) indicate that global ocean temperatures are continuing to warm. This is pretty undeniable, regardless of any argument over cause. And if you think that my comment about ignorance was name calling, it wasn’t – I meant only that lots of people seem ignorant (i.e. uninformed) about these issues.

    STevo; The scenario you describe where pH decreases, but carbonate ions increase, may be possible at some pH levels, but not at any that presently exist in the ocean.

    Adding CO2 to seawater causes CO2 + H20 => H2CO3 (carbonic acid) => HCO3 + H+, with some further dissociation to CO3 + H+. But because CO3+H+ => HCO3, is thermodynamically preferred, the extra protons that are produced by adding CO2 to seawater mostly react with any excess CO3. The net result is a reduction in carbonate (CO3) ions with decreasing pH.

    I don’t understand the economic analogy. But oceanographers are not simply measuring pH. They are characterizing the entire carbonate system, which includes alkalinity, pCO2, pH, and total dissolved inorganic carbon. Knowing any 2 of these 4 allows one to calculate the others, as well as HCO3, CO3, pCO2, pH, aragonite and calcite saturation states. Carbonate is perhaps the most difficult parameter to measure among these. pH is easier, but can be used as one element to calculate all.

    hunter – can you somehow get beyond your whining or at least say something that does more than exhibit how little you understand about these issues?

  • hunter

    James,
    Thank you for your replies.
    Since I am not the one who fabricated the term ‘ocean acidification’, I do not think that I am missing the point when I offer that the term is wrong.
    You claim ocean pH is changing.
    Please post the link to demonstrate that the oceans have changed pH beyond the margin of error.
    You can call my pointing out that the oceans are not changing pH in any meaningful way whining or anything else you want. You are still wrong.
    What I contribute is to simply point out that you Emperors are naked.

  • Richard

    Keith H.
    At the risk of being ridiculous and in the interest of levity I would suggest that your argument ignores the biosphere at it’s peril. It is precisely because the ocean chemistry favors dissolution of CaCO3(as you so eloquently point out)that Miss Coen’s experiment is relevant. It speaks to the process whereby shell building organisms (me with the soda straw) can grow their shells in a hostile environment. The world is not a sterile beaker in some lab. The biosphere is full of little internalized beakers where organisms do their chemical wizardry, all beyond our control I might point out. The bottom line is determined by the net rates of all the reactions involved, and those rates defy our understanding and quantifying.

    The very proposition that life exists defies the laws of thermodynamics on a purely chemical level. If it were a theory you would be skeptical. The idea that CO2 will injure the Earth is preposterous. It is the stuff of life. Approximately 19% of our bodies are composed of carbon. CO2 availability is the rate limiting step in photosynthesis, be it the atmosphere or the ocean. Add CO2 and the rate goes up. I will attempt a flow chart:
    ? ?
    ? ? ? ?
    ? ? ?
    ocean + CO2 + phytoplankton + sunlight -> carbohydrate -> metabolism-> energy + CO2 + Ca= CaCO3-> sedimentation(carbon sequestration). ?=unknowns. lots of unknowns floating around.
    ? ?

    ? ? ? ?

    The Biosphere is a riotous orgy of opportunism that is never in equilibrium as it interacts with the lithosphere, the hydrosphere, and the atmosphere. Everything cycling, rinsing and repeating. We are merely a part of this grand self perpetuating chaotic system, not apart from it. We do not drive the Earth, it gives us a ride.

    Take a walk down the Kaibab trail in Grand Canyon and you will traverse the Red Wall limestone series, 200 meters of CO2 rich sediment sequestered by little critters over eons of time. Once it was atmospheric carbon(conjecture). I always feel very insignificant when I visit there. Bear in mind that all proxy data is conjecture.

    I will say that words have meaning. When you use the word acidification of the ocean what you really mean is neutralization. Once the “problem” crosses the pH threshold of 7 by all means call it acidification.

  • hunter

    James,
    BTW, it is incredibly interesting that it is *known* that the oceans are getting more acidic when there is no evidence to support that *knowing*.
    There are models which imply this ‘acidification’ is happening, but a real scientist would, in the absence of evidence of the change of pH, check their assumptions and look for explanations of how the oceans can uptake the extra CO2 we contribute without changes in pH.
    But then, that would require having what is apparent shortage in the AGW community: an open mind willing to follow evidence in the real world.

  • Keith H

    Hunter: <>James, BTW, it is incredibly interesting that it is *known* that the oceans are getting more acidic >>when there is no evidence to support that *knowing*.

    This is incorrect. There is direct evidence that ocean pH is decreasing as CO2 in the atmosphere rises. Much is published in the scientific literature. A recent example:

    “Physical and biogeochemical modulation of ocean acidification in the central North Pacific”
    John E. Dore, Roger Lukas, Daniel W. Sadler, Matthew J. Church and David M. Karl
    PNAS July 28, 2009 vol. 106 no. 30 12235-12240

    To make such a bold claim about there being no evidence implies that you are familiar with the scientific literature. That does not seem to be the case here.

    To “Chemist” concerning the fact that there are many other reactions buffering the pH in the ocean. Yes, of course you are right about their importance. However, thermodynamics isn’t everything. The problem is that these mineral equilibria, including those with CaCO3, are all far too slow compared to the rate at which CO2 is being absorbed for their effects to be important. Take a look at the literature concerning CaCO3 dissolution during the late Paleocene Thermal Event. It took 100,000 years for the ocean to recover from the acidification caused by that event. Prent day acidification is happening several orders of magnitude faster than that.

    Furthermore, if you were right then the observed decreases in pH, with accompanying changes in CO2 chemistry, as described in the PNAS paper above and elsewhere, would not be happening. But they are.

  • Keith H

    Hunter: “I think you are fibbing about who you are, what you do, and who you know… The other is that you write like a troll, not a serious worker. Perhaps you know those researchers as you clean their offices, but you do not know them as peers.”

    Try googling “Keith Hunter marine chemistry” and you’ll find out who I am & what I do. You will also understand that I didn’t use my surname in the post to avoid confusion with you on this site.

  • Chemist

    Keith H said;-

    “The problem is that these mineral equilibria, including those with CaCO3, are all far too slow compared to the rate at which CO2 is being absorbed for their effects to be important.”

    Keith,

    The paper by Dore et al quotes a decreasing trend of 0.0019 pH units per year (over 20 years) in surface water measured in the Pacific at Station ALOHA near Hawaii. This is a very low rate of acidification indeed. To put it into perspective, if this rate was to continue unchanged for the next 100 years the pH of Pacific surface waters would only decrease from 8.2 to 8.0. And there is no guarantee that surface pH would even continue to drop at this rate before the buffering effects I previously mentioned start to counteract it. The main thrust of Dore’s paper was more to do with the stratification of pH within the subsurface ocean layers than quantifying ocean acidification. Their main point was that physical and biogeochemical processes alter the acidification rate with depth and time and must therefore be given due consideration when designing and interpreting ocean pH monitoring efforts and predictive models. These layers are influenced by remote water mass formation and intrusion, and biologicalcarbon remineralization. The latter I referred to in detail in my last post.

    In summary then this paper holds little evidence for significant ocean acidification.

    Keith H said;-

    “Take a look at the literature concerning CaCO3 dissolution during the late Paleocene Thermal Event. It took 100,000 years for the ocean to recover from the acidification caused by that event. Prent day acidification is happening several orders of magnitude faster than that.”

    Keith,

    The literature variously attribiutes the Paleocene-Eocene thermal maximum (PETM) to either the rapid release of ~2000 x 10^9 metric tons of carbon in the form of methane from ocean methane hydrates or the oxidation of 8000-9000 x 10^9 metric tonnes of carbon as organic matter in shallow marine and near shore terrestrial sediments following the retreat of major epicontinental seaways in the Paleocene. Neither of these events can be compared in the slightest to the increase in atmospheric CO2 attributed to anthropogenic sources over the last 100 years or so. And to claim that “present day acidification is happening several orders of magnitude faster than that” is stretching the truth more than a little. If you are able to provide referrences to any research which supports your claim I would be very interested.

    Keith H said;-

    “Furthermore, if you were right then the observed decreases in pH, with accompanying changes in CO2 chemistry, as described in the PNAS paper above and elsewhere, would not be happening. But they are.”

    As I previously pointed out, there is nothing in Dore’s paper to indicate an abnormal drop in ocean pH, nor any prediction as to whether the very small measured drop in surface pH at the ALOHA station will continue at the same rate as the last 20 years.

    In addition, the papers I referenced in my last post all indicate that there is little if any negative effect of ocean acidification on marine organisms

    Regards…

  • hunter

    Dr. Hunter,
    You are, to say the least, well qualified, and I apologize for the snide remark about your relationship to your peers.
    A question that comes to mind is this:
    How much confidence should anyone have in this claim:
    Time pH pH change Source

    Pre-industrial (1700s) 8.179 0.000 analysed field[3]

    Recent past (1990s) 8.104 −0.075 field[3]

    2050 (2×CO2 = 560 ppm) 7.949 −0.230 model[2]

    2100 (IS92a)[8] 7.824 −0.355 model[2]
    one- how could any measure of the 18th century have that level of accuracy?
    two- changes in the -10^3 seem, even if credible, minor
    three – Why should anyone base anything on climate related projections given the dubious nature of the models?

  • Keith H

    Hunter: Your apology is accepted.

    The “modelled” values for 1750, which suggest an average decrease in pH since 1750 of 0.1 pH unit are not actually models in the sense of, for example, models of future warming. They are based on direct measurements of changes in the CO2 system in upper ocean waters based largely on the WOCE and JGOFS programs. As such they are pretty robust.

    The best research shows that measurements of any 2 out of 4 of the main parameters of the CO2 system, i.e. total inorganic CO2, total alkalinity, CO2 partial pressure and pH, can be accurately interconverted, at least with enough precision to make reasoned arguments about pH changes. Those of in the field simply regard pH as a parameter that measures the changes in CO2 speciation, not an end in itself.

    The models on future scenarios for CO2 speciation (i.e. ocean acidification in the future) are essentially based on the present day observations of CO2 uptake and IPCC predicted scenarios for future atmospheric CO2 levels. Clearly there is some uncertainty in this. For example, I am not aware that rising sea surface temperature has yet been factored in.

    And to all those on this site who think I am ignoring biology, I am not. My remarks have been restricted to the false arguments and erros associated with the chemistry of this issue. The biological responses to decreasing pH in the ocean are not simple, and all of the academy-based statements (e.g. Royal Society) concede that. It may be that decreasing pH may not matter in the long run. But it would be extremely dangerous to assume that without clear evidence.

  • Keith H

    Chemist: I still think that you are confused in your arguments, For example, you quoted this reaction

    CO2(g) + H2O + Ca2+(aq) -> CaCO3(s) + 2 H+(aq)

    and went on to argue that an increase in CO2 partial pressure in the atmosphere will be neutralized by the formation of CaCO3. If you really are a chemist, as your pseudonym suggests/purports, then have you noticed the two H+ ions on the right hand side of the equation? What are they going to do to the pH of the water?

    In fact you have written the wrong reaction entirely. You can’t make CaCO3 out of CO2 unless you supply, in addition to the Ca2+ ion, 2 equivalents of base to convert the CO2 to CO3= (carbonate ions). The correct reaction is

    CaCO3 + CO2 + H2O -> Ca2+ + 2 HCO3-

    This demonstrates that an increase in CO2 partial pressure brings about the dissolution of CaCO3, not its formation. In fact, it also shows that the formation of CaCO3 is accompanied by the release of CO2, which lowers seawater pH. This situation is well understood in the field of marine chemistry.

    As far as your more recent comments go, I think you are cherry picking, especially in your choise of studies that show no biological effects. Some show positive effects, some negative effects, and some no effect.

    The estimated pH decrease for the global ocean since 1750 is 0.1 units, which is an annual rate not dissimilar to that measured at various ocean sites including ALOHA. The CO2 uptake rate, and therefore pH reduction, is not uniform over the ocean surface, and is greatest at sites other that ALOHA, e.g. the North Atlantic and the Southern Ocean.

    The quantity of methane released during the LPTM event is smaller that the quantity of estimated fossil fuel reserves, whose complete release we are talking about if we continue to burn them and avoid other energy solutions.

    In any case, you haven’t answered my fundamental criticism of your view. The LPTM event shows that it took the deep ocean CaCO3 system about 100,000 years to stabilize the CO2 system of the ocean after the initial acidification event. This is well understood in terms of the rates of processes involving dissolution of the deep water CaCO3 reservoir. You can argue all you like about the importance of these mineral reactions, but they will not kick in over the next few centuries when CO2 levels will continue to increase (unless we stop burning fossil fuels).

  • Chemist

    Keith H said;

    “I still think that you are confused in your arguments, For example, you quoted this reaction

    CO2(g) + H2O + Ca2+(aq) -> CaCO3(s) + 2 H+(aq)

    and went on to argue that an increase in CO2 partial pressure in the atmosphere will be neutralized by the formation of CaCO3. If you

    really are a chemist, as your pseudonym suggests/purports, then have you noticed the two H+ ions on the right hand side of the equation?

    What are they going to do to the pH of the water?”

    Keith,

    Firstly, Yes… I really am a chemist… I’m a chemist with over 35 years occupational experience and secondly, if you read my post

    carefully you will see that I clearly said that the fixation of calcium carbonate can be *summarised* in the following *overall* *net*

    reaction;-

    CO2(g) + H2O + Ca2+(aq) -> CaCO3(s) + 2 H+(aq)

    Which is the net reaction of the following partial reactions;-

    CO2 (g) CO2 (aq)

    CO2 (aq) + H2O H2CO3 (aq)

    H2CO3 (aq) H+ (aq) + HCO3- (aq)

    HCO3- (aq) H+ (aq) + CO32- (aq)

    CO32- (aq) + Ca2+ (aq) CaCO3 (s)

    If you think it is not, then please show me why.

    Keith H said;

    “In fact you have written the wrong reaction entirely. You can’t make CaCO3 out of CO2 unless you supply, in addition to the Ca2+ ion, 2

    equivalents of base to convert the CO2 to CO3= (carbonate ions). The correct reaction is

    CaCO3 + CO2 + H2O -> Ca2+ + 2 HCO3-

    This demonstrates that an increase in CO2 partial pressure brings about the dissolution of CaCO3, not its formation. In fact, it also

    shows that the formation of CaCO3 is accompanied by the release of CO2, which lowers seawater pH. This situation is well understood in

    the field of marine chemistry.”

    Keith,

    The reaction you have written above can NEVER make CaCO3 out of CO2 since both are on the same side of the equation ie they are either

    both reactants or in the case of a reversable reaction, both products. Since all CaCO3 in the ocean is the result of CO2 fixation in

    reaction with dissolved calcium ions (Ca+2). Your reaction makes no logical sense and I can’t believe that a person supposedly intimate

    with marine chemistry would make such a mistake.

    Keith H said;-

    “The estimated pH decrease for the global ocean since 1750 is 0.1 units, which is an annual rate not dissimilar to that measured at

    various ocean sites including ALOHA.”

    Keith,

    Sorry if I sound sceptical but perhaps you would like to tell me exactly how this co-called ‘estimate’ has been made. What empirical data was used? What is the degree of error involved in the estimate?

    Keith H said;-

    “In any case, you haven’t answered my fundamental criticism of your view. The LPTM event shows that it took the deep ocean CaCO3 system

    about 100,000 years to stabilize the CO2 system of the ocean after the initial acidification event. This is well understood in terms of

    the rates of processes involving dissolution of the deep water CaCO3 reservoir. You can argue all you like about the importance of these

    mineral reactions, but they will not kick in over the next few centuries when CO2 levels will continue to increase (unless we stop

    burning fossil fuels).”

    Keith,

    And in those 100,000 years what happened to the evolution of CaCO3-fixing marine creatures, particularly the larger Foraminifera?

    Regards,

  • Steve Bloom

    Chemist, why are you asking those questions if you’re familiar with the relevant literature regarding pH during the LPTM? The points Keith H made are undisputed.

    BTW, I also understand from the literature that due to buffering pH was not radically lower during past periods of high CO2 except when a fast excursion was involved (as with the LPTM).

    While the LPTM stands as a worst-case cautionary tale, it might be more useful to consider the very near-future implications of this new review paper by leading coral reef experts (title/abstract):

    “The coral reef crisis: The critical importance of <350 ppm CO2

    “Temperature-induced mass coral bleaching causing mortality on a wide geographic scale started when atmospheric CO2 levels exceeded 320 ppm. When CO2 levels reached 340 ppm, sporadic but highly destructive mass bleaching occurred in most reefs world-wide, often associated with El Niño events. Recovery was dependent on the vulnerability of individual reef areas and on the reef’s previous history and resilience. At today’s level of 387 ppm, allowing a lag-time of 10 years for sea temperatures to respond, most reefs world-wide are committed to an irreversible decline. Mass bleaching will in future become annual, departing from the 4 to 7 years return-time of El Niño events. Bleaching will be exacerbated by the effects of degraded water-quality and increased severe weather events. In addition, the progressive onset of ocean acidification will cause reduction of coral growth and retardation of the growth of high magnesium calcite-secreting coralline algae. If CO2 levels are allowed to reach 450 ppm (due to occur by 2030–2040 at the current rates), reefs will be in rapid and terminal decline world-wide from multiple synergies arising from mass bleaching, ocean acidification, and other environmental impacts. Damage to shallow reef communities will become extensive with consequent reduction of biodiversity followed by extinctions. Reefs will cease to be large-scale nursery grounds for fish and will cease to have most of their current value to humanity. There will be knock-on effects to ecosystems associated with reefs, and to other pelagic and benthic ecosystems. Should CO2 levels reach 600 ppm reefs will be eroding geological structures with populations of surviving biota restricted to refuges. Domino effects will follow, affecting many other marine ecosystems. This is likely to have been the path of great mass extinctions of the past, adding to the case that anthropogenic CO2 emissions could trigger the Earth’s sixth mass extinction.”

    BTW, anyone with a complaint about the term “ocean acidification” can register it with the lead author of the paper.

  • Keith H

    Chemist: Your comments imply that you are not familiar with the literature concerning calcification in the ocean. I suggest you do something about that before accusing people who actually work in the field of making mistakes. Your arguments are simply wrong. Completely. And you still haven’t answered the question about the slow rate of the mineral interactions.

    As far as how the 0.1 decrease in pH since 1850 was calculated, and its uncertainties & assumptions, I suggest you read the literature on that too.

    Steve Bloom: You are absolutely correct. pH excursions in the past ocean are relatively small because the burial of CaCO3 in the ocean buffers against it over millenial time scales (not fast enough to help us now).

  • Steve Bloom

    From the London Telegraph:

    Arctic Ocean acid ‘will dissolve shells of sea creatures within 10 years’

    The Arctic Ocean is becoming acidic so quickly that it will reach corrosive levels within 10 years, a leading scientist has warned.

    By Matthew Moore
    Published: 4:33PM BST 04 Oct 2009

    Waters around the North Pole are absorbing carbon dioxide at such a rate that they will soon start dissolving the shells of living sea creatures.

    The potentially disastrous consequences for the food chain have been highlighted by Professor Jean-Pierre Gattuso of the National Centre for Scientific Research in France.

    His team of oceanographers have produced startling predictions about the acidity of the Arctic Ocean after research carried out on the Svalbard archipelago, a group of islands half way between Norway and the North Pole, revealed that the problem is more advanced than scientists thought.

    Their forecasts suggest that by 2018, 10 per cent of the ocean will be corrosively acidic, rising to 50 per cent in 2050. By 2100 the entire Arctic Ocean will be inhospitable to shellfish, they predict.

    “This is extremely worrying,” Prof Gattuso told the Oceans of Tomorrow conference in Barcelona.

    “We knew that the seas were getting more acidic and this would disrupt the ability of shellfish – like mussels – to grow their shells. But now we realise the situation is much worse.”

    One of the most vulnerable creatures is likely to be the mollusc Limacina helicina, which seabirds, whales and several species of fish rely on for food.

    The process of acidification – by which carbon dioxide emitted into the atmosphere as pollution is absorbed by water and converted into carbonic acid – is taking places in seas and oceans across the world.

    But the prognosis is particularly bleak in the polar regions because the gas is more soluble in cold water than hot water.

    “Over the whole planet, there will be a threefold increase in the average acidity of the oceans, which is unprecedented during the past 20 million years,” Prof Gattuso said

    “That level of acidification will cause immense damage to the ecosystem and the food chain, particularly in the Arctic.”

    Prof Gattuso told the conference that hi-tech proposals for limiting the extent of climate change would have no affect on reducing the acidity of the oceans, and urged immediate action to cut greenhouse gas emissions.

    “Scientists have proposed all sorts of geo-engineering solutions to global warming. For instance, they have proposed spraying the upper atmosphere with aerosol particles that would reduce sunlight reaching the Earth, mitigating the warming caused by rising levels of carbon dioxide,” he said.

    “But these ideas miss the point. They will still allow carbon dioxide emissions to continue to increase – and thus the oceans to become more and more acidic.

    “There is only one way to stop the devastation the oceans are now facing and that is to limit carbon-dioxide emissions as a matter of urgency.”

    The increasing acidity of the Arctic Ocean may have a direct impact on the marine life of the British Isles, as the Lophelia pertusa coral responsible for creating reefs off the coast of Scotland is killed off.

  • Chemist

    Steve Bloom said;

    “Chemist, why are you asking those questions if you’re familiar with the relevant literature regarding pH during the LPTM? The points Keith H made are undisputed.”

    No, some of the facts (the correct ones) that Keith Hunter made may be undisputed, however the implications and interpretations are far from being undisputed. That is what science is all about.

    The day that any aspect of of science which is as new and as complex as the hypothesis of AGW is truly considered “undisputed” or “Settled” is the day I will leave science, because that is that day that science has turned into more of a religion than true science.

  • Chemist

    Keith H said;-

    “Your comments imply that you are not familiar with the literature concerning calcification in the ocean. I suggest you do something about that before accusing people who actually work in the field of making mistakes. Your arguments are simply wrong. Completely.”

    LOL. Are you suggesting that the reaction *you* provided;-

    CaCO3 + CO2 + H2O -> Ca2+ + 2 HCO3-

    which supposedly describes the formation of CaCO3 in the ocean from Ca2+ and CO2 is correct?

    In your reaction, rather than being consumed during the deposition of CaCO3, CO2 is released!? When did that start happening?

  • Steve Bloom

    Chemist, why are you conflating ocean acidification with AGW? Please stay on topic.

    Re the specific chemical reactions involved in acidification, all of that was laid out in the literature some years ago. Unless it’s being asserted that those results are wrong, I don’t see the point of arguing about who here is stating this or that reaction correctly.

  • Chemist

    Steve Bloom,

    Are you suggesting that all this hype about ocean acidification is not related to the AGW alarmist agenda?

    Just four posts back you cut and pasted a sensationalist newspaper article which claimed that the Arctic Ocean acid ‘will dissolve shells of sea creatures within 10 years’. And further that “The process of acidification – by which carbon dioxide emitted into the atmosphere as pollution is absorbed by water and converted into carbonic acid – is taking places in seas and oceans across the world.”

    Then you have the gall to suggest that *I* am “conflating ocean acidification with AGW”.

    Go back to reading your newspapers!

  • Steve Bloom

    Chemist, they’re certainly related on the level of concern about continuing to add CO2 to the atmosphere. Not otherwise, though, noting that different subsets of scientists and independent bodies of research are involved in each. That said, I’m not sure what your point is.

    I agree that the article I posted is sensational, but note that it refers to results reported at a scientific conference, based on research conducted over several years by a sizable team of scientists working in the Arctic. We’ll see what the published results say, but it seems clear enough from the article (and several independently-written ones that can be found via Google News) that a sharp trend toward acidification has been measured in the Arctic. Combine that with the fact that there are good physical reasons to expect acidification to be led by the Arctic Ocean and the reported results become hard to ignore.

    As regards the article’s statement about acidification happening globally, Keith H referenced a paper demonstrating that. You expressed dislike for the paper’s conclusions, but provided no details as to why. Please explain.

    But bearing in mind again that we have no details about the new Arctic results, it might be more constructive to focus on the new review paper I also linked. Do you have any comments on that?

  • hunter

    Steve Bloom,
    Your posts about the sea and the risks of CO2 are bs.
    And then you have the gall to give skeptics a hard time for restating what you yourself have posted.
    One of the annoying aspects of AGW sheepdom is their inability to think past bleating out cut-n-paste fear mongering pap and then fleeing any rational defense of it.
    The peer process, as has been devastatingly demonstrated irt AGW, is dysfunctional at best.
    Why should anyone place any credence at all in yet more extreme, inflammatory and bogus AGW papers?

  • Keith H

    Chemist: “In your reaction, rather than being consumed during the deposition of CaCO3, CO2 is released!? When did that start happening?”

    It always has. As I said before, stop using your own opinions and read up some literature about the calcification process. It all comes back to those 2 equivalents of base that you need to convert CO2 to CO3= in order to make CaCO3. They cannot be conveniently forgotten, as you are doing. Use your chemical training to figure out where they come from. Hint: The most abundant base in seawater, by far, is HCO3-. If HCO3- functions as a base, what conjugate acid does it form?

    Steve Bloom is right. All of this is in the scientific literature. Has been for years.

  • Steve Bloom

    hunter, you know they’re bs how? Did you read the review paper I linked?

  • Chemist

    >>Chemist: “In your reaction, rather than being consumed during the deposition of CaCO3, CO2 is released!? When did that start happening?”

    >Keith H: “It always has.”

    ROFL! And guys like you are supposedly at the forefront of marine chemistry???? Good grief!!!

    I give up!

  • hunter

    Keith H,
    Perhaps you would guide us on the net impact calcification has on CO2?
    I am on the way our of state for a few days, but I will speculate now that the net impact of calcification is to reduce the amount of CO2.

  • Keith H

    Chemist: “ROFL! And guys like you are supposedly at the forefront of marine chemistry???? Good grief!!!
    I give up!”

    Don’t give up. Take up a challenge to test how confident you are in your knowledge. Submit a paper to a journal such as “Marine Chemistry” (Elsevier) rebutting what I have written, i.e. that calcification produces CO2 i.e. that this reaction is wrong:

    Ca++ + 2 HCO3- -> CaCO3 + CO2 + H2O

    Better still, submit it to “Nature Geosciences” or a similar high-impact journal so that the millions can find out how much cleverer you are than those of us who do research in the field. I bet you don’t

  • Keith H

    Hunter: Here’s a primer. CaCO3 and CO2 are part of the carbon cycle. CaCO3 in continental rocks & soild are weathered thus

    CaCO3 + CO2 + H2O -> Ca(HCO3)2

    This enters the ocean, and means that Ca(HCO3) is usually the most abundant species in river water. The rate at which this weathering occurs is such that if CO2 wasn’t returned to the atmosphere, it would all be consumed in a few thousand years. Clearly that is not the case. In the ocean, CaCO3 is formed (by calcifying organisms) by the reverse reaction

    Ca(HCO3)2 -> CaCO3 + CO2 + H2O

    Some CaCO3 formed in the ocean redissolves in deep water. This has no net effect on the CO2 originally lost by weathering. However, the CaCO3 that gets preserved in marine sediments adds an equivalent amount of CO2 back to the system. The whole cycle is balanced so that the weathering loss of CO2 is restored and the CO2 level in the atmosphere is more or less stable.

    These processes (weathering and preservation of CaCO3 in the ocean) control atmospheric CO2 on time scales of millenia. It is often called the climate “thermostat”. In this steady-state world, calcification controls CO2 to a fixed level.

    If extra CO2 is added to the system, e.g. from fossil fuels, it will mean that net calcification in the ocean must decrease. The weathering reactions will not respond to the extra CO2 in the atmosphere because they occur too slowly. Therefore the net effect of extra CO2 is to dissolve pre-existing CaCO3 in the ocean. Once the CaCO3 has dissolved, CO2 levels will return to what they were (more or less) before the fossil fuel input, restoring the original balance.

    So to your question: what is the net effect of calcification on CO2? The answer is that CaCO3 **dissolution**, not formation, will cause a decrease in CO2. This is why marine scientists are concerned, because some of the CaCO3 is in the form of living organisms that may not be able to resist dissolution. There are some organisms that seem to respond to acidification by CO2 by increasing their calcification rate. The net effect of these on CO2 levels is neutral, because for every carbon atom they remove as CaCO3, they generate one CO2 molecule (in this I am discounting the organic matter in the same organisms because it is only transiently present and converts back to CO2 after death).

  • hunter

    Dr. Hunter,
    So from your first equation,
    Ca++ + 2 HCO3- -> CaCO3 + CO2 + H2O, the net effect of the chemical reaction is a reduction of C by one, a net reduction.
    And from reading you, it appears that the pH number give as the net move of pH during industrialization is a derived number based on the understanding you and other workers have from studying the carbon and calcium cycles.
    Do you feel there is any problem between estimates of pH and field observations?
    As much as you and your coleagues have worked, do you feel there are still areas to be well understood in these dynamic cycles?

  • Steve Bloom

    The Ca stands for calcium, hunter, so there’s no loss of a C. There are two on the left and two on the right.

  • hunter

    Steve Bloom,
    I know the difference between Ca and C.
    I was referring to the extra C in the HCO3.

  • Steve Bloom

    There isn’t one. You’re not reading the equation correctly.

  • Delfin J Beltran MD

    In a prior comment the pH of oceanic water is apparently alkaline, the pH is greater that 7.0. pH 7.0 is neutrality or a balance of acid and alkaline ions. If a solution is acidic that means that there exist in the solution more H+ or hydrogen ions. If a solution is alkaline that means that the available H+ ions are fewer in number that the available OH- or hydroxyl ions. pure water ionizes into equal quantities of H+ and OH- ions. If an acid such as hydrochloric acid is added to water the number of H+ ions will increase and the number of OH- ions will remain the same so the solution will test with an excess of H+ ions or test acidic. If an alkali such as sodium hydroxide, NaOH, a salt formed by the addition of metallic sodium to water that occurs with explosive rapidity that releases H+ hydrogen ions plus heat energy and the H+ ions very promptly combine with the available oxygen to form heat and water, H2O. The addition of NaOH to water causes the water to have an excess of hydroxyl ions with no change in the number of H+ ions thus the water tests alkaline. Referring back to the initial statement that oceanic water is alkaline defines that there are more hydroxyl ions available in ocean water than hydrogen ions. Incidentally, ions are the charged particles that are formed when a soluble substance dissolves into the water medium. As stated before pure water ionizes or separates from one molecue of water H2O into one ion of hydrogen H+ and one ion of hydroxy OH- thus forming equal numbers of each since there are no other chemicals in the pure water. (This thesis can be complicated by greater knowledge and teaching that involves principles of thermodynamics that are not pertinent at this level.) When carbon dioxide enters into a water solution as it does whenever oxygen in a living cell combines with a carbon atom from the food that we eat the chemical product enters the solution to form Carbonic Acid. Carbonic acid undergoes a dual stage of ionization. Carbon Dioxide (C–,2O+) plus water ( 2H+. O–) forms carbonic acid, also known as soda pop or selzer water ( H2O + CO2 = H2CO3 ) which in turn ionizes into H+ and HCO3 or one H+ ion and one bicarbonate ion. The degree to which this ionization reaction takes place has been defined by Henderson and Hasselbach in a complex formula that relates the concentration of base bicarbonate ion BHCO3 to the acid bicarbonate ion HCO3 thus BHCO3/H2CO3 where B is an ion of some soluble metal in the solution. This new system of fixed concentration proportions of the two element factors is called a buffer system because it has the ability to maintain a constant ratio of the two forms of bicarbonate and consequently a fixed concentration of acid H+. Thus the addition of acid to a solution is prevented from becoming more acid by the addition of CO2 as the amount of CO2 absorbed into the water will be limited by the buffer action that controls the respiration cycles of oceanic water. At the same time CO2 will need to be absorbed into the ocean to buffer the fixed acids such as phosphate fertilizers, sulfur compounds and the products of metabolism from the living sea creatres and the acid products of their death. Thus it is seen that rather than being a destructive force in the oceans carbon dioxide is life giving just as it is the food for the chlorophyl plus sunlight energy storage and growth system.

  • Delfin J Beltran MD

    There are several comments in this series that refer to experiments of adding acid to water or adding CO2 to water and thus making an analogy. These are interesting but incomplete for analogy as the ocean is neither pure water nor is the addition of fixed acids to water valid analogy. Because the ocean contains multiple metallic ions such as iron, calcium, sodium and their also exist other alkaline ions such as the phosphates, sulfates and their is also probably a certain amount of proteinaceous material the ocean is more likely to respond in manners similar to the human respiratory system in which the removal of metabolic CO2 from the cell through the circulation to the ventilation of gases in the pulmonary system is the flux of the CO2. The excess beyond the buffering needs as determined by the respiratory centers is exhaled. There is also the factor of oceanic temperature changes and the circulation within the large body of water. As regards CO2 content of water, all gases are less soluble in warmer water thus as the water is warmed during the day by insolation (solar energy transmitted into the water) the CO2 as well as any other dissolved gas such as oxygen will be respired to the ambient air. This is in agreement with the unaltered data curves ( Mr Gore’s graphs were altered by mislabeling) which demonstrate the correct sequence of warmer climate preceeding elevated ambient air CO2 content. This would also be related to the consequent increase of chlorophyl containing vegetation. So if there has been global warming in the past it will be followed by increased vegetation such as in North America where forestion is greater today than it was at the time the white man invaded the indian territories. These concepts are more in agreement with the scientific presentations by Lord Christopher Monckton that demonstrate the data juggling, incorrect interpretations of phenomena data and artistic graph creation that is not supported by a valid data base. Arguement at the level of importance of global warming requires valid scientific investigation and reporting, not repetative guesses as to what the political arguer wishes to be the truth.

  • http://selfdestructivebastards.blogspot.com/ Canada Guy

    Here’s a summary of some of the environmental threats to our oceans. The way things are going, there could be no fish left in the oceans in as little as 40 years.

    http://selfdestructivebastards.blogspot.com/2009/10/our-oceans-are-dying.html

  • hunter

    Canada Guy,
    The good news is that the idea we can kill the oceans is utter crap.
    Be happy.
    We are not all going to die.