Is “ocean acidification” a threat?

By Roger Andrews

One of the many potential threats posed by rising CO2 and climate change is “ocean acidification”, a term I put in quotes because with a pH around 8.1 the ocean is still a very long way from becoming acidic. I’ve chosen it as the topic for this post for three reasons: first because the basics can be handled briefly, second because some comments on recent threads have expressed concern about it, and third because the way the data are usually presented gives an exaggerated idea of the rate at which the oceans are being “acidified”. Here’s an example:

We see CO2 in the atmosphere rising at a rapid clip, we see CO2 in seawater rising with it and we see ocean pH decreasing at what appears to be about the same rate.

But what we’re actually looking at is a decrease in pH of about 0.034 units on a scale that goes from zero to fourteen, i.e. a change of a little over 0.2 percent. We see the decrease in its true perspective when we re-plot the data (from the Hawaii Ocean Time Series project ALOHA site) using an expanded Y scale that begins at pH=7 (neutral):

A downward trend is still visible, but it’s very, very small (note that only actual pH measurements, not estimates, are plotted). If it continues at the same rate ocean pH will still be close to 8 in 2100 and the oceans won’t become truly acidic (pH=6.9) until about the year 2800. And even then the level of acidity will be minimal (natural rainwater has a pH of 5.6).

But the trend probably won’t continue at the same rate. The ocean absorbs CO2 from the atmosphere, so the rate of ocean pH decrease will be largely (although not entirely) dependent on future atmospheric CO2 concentrations. Before we can make estimates of future ocean pH values we therefore need some future CO2 scenarios, and the IPCC provides us with four in the AR5:

RCP2.6: Atmospheric CO2 increases to 440 ppm by 2100
RCP4.5: Atmospheric CO2 increases to 580 ppm by 2100
RCP6.0: Atmospheric CO2 increases to 650 ppm by 2100
RCP8.5: Atmospheric CO2 increases to 930 ppm by 2100

We also need to establish a numerical relationship between atmospheric CO2 and ocean pH, and a trend line drawn through an XY plot that compares the ALOHA pH data with Mauna Loa CO2 shows pH decreasing by 0.094 units for every 100 ppm increase in atmospheric CO2:

Applying this rate of increase to the IPCC CO2 concentrations gives predicted 2100 ocean pHs of 8.0 for RCP2.6, 7.9 for RCP4.5, 7.8 for RCP6.0 and 7.6 for RCP8.5. The scenario that gives the lowest pH is the RCP8.5 “worst case”, and here it is plotted up:

There are, however, reasons to believe that this plot is worse than a “worst” case. As Dave Rutledge pointed out in his recent post the RCP8.5 scenario burns twice as much coal by 2100 as is known to exist, and we also aren’t taking into account the fact that the more CO2 the ocean contains the less it absorbs. The Keeling Institute puts it thus:

“ …. although the oceans presently take up about one-fourth of the excess CO2 human activities put into the air, that fraction was significantly larger at the beginning of the Industrial Revolution. That’s for a number of reasons, starting with the simple one that as one dissolves CO2 into a given volume of seawater, there is a growing resistance to adding still more CO2.”

The likelihood is therefore that both CO2 concentrations and the amount of CO2 absorbed by the oceans will have been overestimated, in which case the projected 2100 ocean pH of ~7.6 for the RCP8.5 case will be too low. But let’s assume anyway that ocean pHs in 2100 will be in the 7.6 range. What impact will this have on marine life? No one knows for sure, but according to Hofmann et al.there are parts of the ocean which routinely reach pH values this low, or lower:

Here, we present a compilation of continuous, high-resolution time series of upper ocean pH, collected using autonomous sensors, over a variety of ecosystems ranging from polar to tropical, open-ocean to coastal, kelp forest to coral reef. These observations reveal a continuum of month-long pH variability with standard deviations from 0.004 to 0.277 and ranges spanning 0.024 to 1.430 pH units (see note). The nature of the observed variability was also highly site-dependent, with characteristic diel, semi-diurnal, and stochastic patterns of varying amplitudes. These biome-specific pH signatures disclose current levels of exposure to both high and low dissolved CO2, often demonstrating that resident organisms are already experiencing pH regimes that are not predicted until 2100.

(Note: The highest pH measured was 8.356 and the lowest 6.699 for measurements taken over 30-day periods. The annual pH range could be significantly larger.)

So is “ocean acidification” a threat? The basic data say it probably isn’t, but there are a number of additional complexities that for reasons of space have not been considered, including:

1. Mixing of surface water with deep water
2. The removal of CO2 by marine organisms
3. The CO2/HCO3/CaCO3 equilibria
4. CO2 dissolution rate as a function of CO2 saturation and temperature.

If any of these are potential game-changers, feel free to say so.

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49 Responses to Is “ocean acidification” a threat?

  1. Nate Hagens says:

    Uhh. I don’t think the author has read the primary lit on OA.

    First of pH is a logarithmic scale, so since beginning of industrial revolution the oceans have become ~30% more acidic.
    And is forecast to become 170% more acidic by 2100
    Second, pteropods are already losing their shells even at this level of change. So it’s not even ‘2100’ (and beyond) that is the issue
    Third, there have been no system wide studies on entire food webs (e.g. cetaceans, pelagic fish) dependent on aragonite and other shelled organisms down the food chain

    I do agree with the author that the higher of the IPCC scenarios won’t come to pass as that amount of fossil fuels are not economically viable – but they don’t include positive feedbacks or disasters (like long burning coal seam fire accidents etc)

    It’s funny/interesting/profound that one can know alot about a persons personality and worldview just by observing one or two of their beliefs. (I hypothesize that anyone concerned about the demise of ocean life in next 100 years will not even read the above links because they already have seen them. And those who cannot fathom that humans are impacting biosphere and biodiversity won’t read them either. There may be 3 people reading this site that are in neither camp.

    Next, the ‘humans can’t possibly impact such a large thing as the earth’ crowd will say that insects are doing great.

    In the end maximum power principle will win out over precautionary principle. Because if we can’t see with our own eyes might happen we’ll wave our hands and ignore it.

    • Roger Andrews says:

      pH is a logarithmic scale, so since beginning of industrial revolution the oceans have become ~30% more acidic.

      The pH scale is a base-10 logarithmic scale that measures the concentration of hydrogen atoms relative to their concentration in distilled water (pH=7). A pH of 8.2 represents a relative hydrogen atom concentration of 0.063 and a pH of 8.1 a relative concentration of 0.079, and the claim that the “oceans have become ~30% more acidic” is derived from the ratio of these two numbers (the increase is actually 26%, but ~30% is close enough).

      This number is just another attempt to scare people. For example, one of your links states that acidity is now expected to increase by a further 170% between now and 2100, enough to turn the oceans into vinegar, one would think. But when you do the calculations the 170% increase works out to a decrease in ocean pH from 8.1 to 7.7, still well on the alkaline side of neutral and in line with the estimates I gave in the post. You could in fact increase “acidity” by a factor of ten and the oceans would still be slightly alkaline (pH=7.1). You would have to increase it by a factor of 300 before the oceans became as acid as rainwater.

    • Euan Mearns says:

      Nate, thanks for thoughtful comment. I am kind of chronically short of time since I am supposed to be on holiday from being retired 😉 So here is some of my reactions to your comment and links.

      1) I am absolutely open minded and to being persuaded about the risks to the oceans from human activity. But I am very sceptical about warmists who hop from global warming (i.e. lower troposphere warming) to deep ocean warming and then ocean acidification. Had they got lower troposphere warming right they wouldn’t need to keep hopping around.

      Your links are interesting but….

      2) The one from Bristol talks about 170% – 170 parts per 100 is simply impossible and says stuff like

      The researchers also found that the world’s oceans are acidifying at an ‘unprecedented rate’, which may be faster than at any time in the past 300 million years.

      I’m afraid the evidence to back this GW speak BS simply does not exist. and..

      3) The link to

      Invertebrate numbers nearly halve as human population doubles


      Kicks off with a picture a tapir. I really do wonder if the folks writing this stuff know the difference between vertebrate and invertebrate.

      This kind of summarises my scepticism. It's not that I don't believe that 7 billion humans are having an impact on the planet Earth but those being paid billions to quantify the impact are doing a truly shit job. And so I am left in a state of suspicion and ignorance.

      One of your other links on pteropods dissolving may actually have some observational basis. But I doubt the cause is "acidification". How could it be so? If it has anything to do with CO2 then I doubt it is linked to the partial pressure of H but more likely linked to the partial pressure of CO2. But more likely it could be linked to a myriad of other processes, either natural or man made, that are quite simply being over looked because the only thing that brings in money these days is CO2 and climate change. It is a scientific catastrophe.

      Can you please explain how you see this working:

      The shell damage corresponds so precisely to where chemical changes have hit the marine world hardest — specific coastal hot spots in Washington and Oregon, where water wells up from the deep on windy days — that NOAA scientists said they could clearly pinpoint the cause: atmospheric CO2.

      The ocean mixing time is of the order 1000 years.

      A confused CW

      • Nate Hagens says:

        Euan my old and good friend.
        I look at these questions differently than you do, and you know this by now.
        We are 2/3 of the way through the habitable time period for this planet – another 2 billion years left +/- is all goes well. What are the things keeping us in this zone? Negative feedbacks in the biosphere – the silicate weathering/volcano carbon give and take over geologic time. On human scales I am not interested in trivia but in the questions of ‘what keeps us in the habitable zone’ for humanity, healthy ecosystems, over deep (perhaps not geologic) time – thousands to hundreds of thousands of years (in our current form alone, humans are 200,000 years old).

        As such, I KNOW that humans are impacting the planet, in deleterious ways. If we can demonstrate that:
        1) we outweigh wild animals 50-1
        2) insect populations are down 45%
        3) we are losing species faster than any time in history other than PETM and asteroid hits

        is it really that much of a stretch to believe we are impacting biogeochemical processes with our waste streams? I am not a climate scientist (neither are you despite it being a passionate hobby of yours). ALL atmospheric, carbon, physicists working on climate that I know (n=9) are between moderately and extremely worried about the future of planetary conditions (n=11 now after I met someone at Stanford last week). Are they confident in the ‘models’? No – the models are increasingly educated guesses only as good as weakest input trying to quantify the physics that has long been known. On the ocean front its worse IMO. Impacts on coral and pteropods etc are happening much faster than ocean experts thought even 5-6 years ago. Do I need to ‘know’ the science to know that scientists are very concerned – en masse – and realize that we are on a precipice of potentially impacting history in a profoundly negative way? I am a well-read generalist, who realizes the amazing odds against there being life on this planet at all, and that we weaved and bobbed our way through millions of years to arrive at exactly this point with our paws firmly clenched on the carbon monkey trap. I am much more interested in the ‘what could go badly wrong and how well do we understand it’ than the chemistry trivia I responded to here.

        Re my comment on personality types. I have 2 hypotheses:
        1) that even though the mechanisms are different (e.g. almost all climate deniers acknowledge that carbon signature of most CO2 rise is anthropogenic but dont think this is as big as natural forcings (or not dangerous) – while ocean acidification skeptics think we are measuring pH wrong and couldnt know what happened in the past etc). Anyways, my hypothesis is that if you take random 1000 people that those who state ‘climate change is not urgent nor primarily human caused’ there will be an 80%-90%+ correlation with the belief ‘ocean acidification is not a real and urgent danger’

        2) furthermore that those who score high on ‘conscientiousness’ and low on ‘openness’ scale on Big5 will be significantly more likely (e.g. by factor of 2-3x) to deny the risks that anthropic CO2 poses to biosphere.

        As to your question about invertebrates – I only specified the insect part of the article – The full article was titled ‘Defaunation in the Anthropocene’ in Science this month. linked here:

        There are many ocean experts in Scotland and the UK. Would be interesting if you would speak to one, not about CO2, but about pH and ongoing impacts, with an open mind. I can introduce you to some folk at Bristol.

        Unfortunately a very large majority (not all) of human reaction, intent and response is based on belief systems, which are in turn largely influenced by personality which is in turn 30-40% influenced by biology. Not a good recipe for a kumba-ya future during the end of growth.

        peace my friend
        sasquatch==>eco-troll Nate

      • Hi Roger, Euan, Nate,

        it’s interesting to see how very intelligent people can ignore excellent work of other intelligent people, and BOTH goups are concerned with the sustainability issues. But as Nate explained, it’s part of our Human Nature.

        Well, regarding the declining ocean’s pH, it’s probably the sigle worst effect of our fossil fuel addiction. Why, it is difficult to explain in one short comment, but I will add one more link (PDF) to Nate’s previous, and this one is a summary for policymakers regarding the ocean acidification (540 experts from 37 countries):

        ( and quotation from there (statement attached with a “high confidence”):

        “Today’s human-induced acidification is a unique event in the geological history of our planet due to its rapid rate of change. An analysis of ocean acidification over the last 300 million years highlights the unprecedented rate of change of the current acidification (31). The most comparable event 55 million years ago was linked to mass extinctions of calcareous deep-sea organisms and significant changes to the surface ocean ecosystem (31). At that time, though the rate of change of ocean pH was rapid, it may have been 10 times slower than current change (32).”

        That citation on according to Euan “BS” claim that OA is fastest in at least 300 000 000 years is from Science:

        Hönisch, B., Ridgwell, A., Schmidt, D.N., Thomas, E., Gibbs, S.J., Sluijs, A., Zeebe, R., Martindale, R.C., Greene, S.E., Kiessling, W., Ries, J., Zachos, J.C., Royer, D.L., Barker, S., Marchitto Jr., T.M., Moyer, R., Pelejero, C., Ziveri, P., Foster, G.L., Williams, B., 2012. The geological record of ocean acidification. Science 335(6072):1058–1063, doi:10.1126/science.1208277.



        • Roger Andrews says:

          It’s interesting to see how very intelligent people can ignore excellent work of other intelligent people, and BOTH goups are concerned with the sustainability issues. But as Nate explained, it’s part of our Human Nature.

          Well, I thought I was intelligent until I agreed to mind the store in Euan’s absence, but now I’m beginning to wonder. 😉

          Anyway, pursuing my search for data I read the Ocean Acidification article you linked to. Once again I found many claims regarding what OA was going to do but zero hard supporting evidence.

          So I went to the references. There are 59 of them. To judge by the titles they are mostly “what if” studies that probably don’t add much in the way of hard data. There were, however, a couple that sounded interesting enough to download. One was:

          This paper presents charts and graphs showing “sensitivities” of different types of marine animals to increasing pCO2, but I’m unable to determine from the text what the results mean in physical terms or whether they come from measurements or assumptions/projections. Maybe someone could enlighten me.

          The second was (full text paywalled)

          I quote from the Abstract:

          We sampled from the top 200 m of the water column, where aragonite saturation levels were around 1, as upwelled deep water is mixed with surface water containing anthropogenic CO2. Comparing the shell structure with samples from aragonite-supersaturated regions elsewhere under a scanning electron microscope, we found severe levels of shell dissolution in the undersaturated region alone. According to laboratory incubations of intact samples with a range of aragonite saturation levels, eight days of incubation in aragonite saturation levels of 0.94–1.12 produces equivalent levels of dissolution. As deep-water upwelling and CO2 absorption by surface waters is likely to increase as a result of human activities, we conclude that upper ocean regions where aragonite-shelled organisms are affected by dissolution are likely to expand.

          I’m beginning to get the impression that adverse “ocean acidification” impacts can be demonstrated only in areas of naturally upwelling low pH ocean water, as was the case with the Oregon oysters, and that adverse impacts from the much smaller pH decreases caused by anthropogenic CO2 have yet to be detected.

  2. Hi Roger,

    Great topic. I believe that the upwelling areas are the most critical ones in the oceans. These are the places with the large fisheries and most of the marine birds and mammals. From the Hofmann link it appears that these areas may already have extremely large pH variations, several tenths within a month. So my sense so far is that the impacts are likely to be limited.


  3. Nate is quite right. This author knows not what he talks about, as evident from how he ‘explains’ pH, etc.

    Regions of naturally low pH at about 7.8 (we’re now averaging ~8.1), have no shelled or skeletal life forms. A good example is the waters near Ischia where natural CO2 leaks form magmatic sources bubble up from the seabed and pH is about 7.8.

    We are, in fact, just years away from massive extinctions of both sea food chains and the natural carbon cycle, which sequesters CO2 in seafloor limestone via calcifying organisms which cannot perform their carbonate chemistry much below pH 8.0 or below 4.0 in carbonate-ion saturation.

    we’ve moved an entire planet”s oceans from pH 8.2 pre-industrial to 8.1 today by emitting ~1.5 trillion tons of fossil fueled CO2 in just 150+ years.

    Our rate of CO2 emission is 100x that of the highest emission rates since the Triassic. Our rates are about equal to those of the earlier, End-Permian extinctions brought on by the vast volcanic emissions over thousands of years that formed the million square km Siberian Traps.

    Anyone not thinking acidification makes warming & sea rise look like peanuts should visit Norwegian fisheries, Alaskan oyster farms, etc.

    Finally, some common press has been alerting average folks to something that was explained by Arrhenius in 1896.

    There are more details here…

    And anyone can ask for further info. We haven’t time for misleading articles.

    Dr. A. Cannara
    650 400 3071

  4. Peter Shaw says:

    A useful overview, to which I would add an issue (sadly absent from the conventional narrative) without which even a brief account is incomplete and misleading.
    Bear with me; this is for the general reader:

    There exist geologically significant deposits of marine limestone (some a few hundred million years old) which are exposed but have not yet redissolved. Marine life makes limestone from temporary hardness in seawater; it follows that each unit of limestone was accompanied by one unit of CO2 released into the ocean, then the air.
    This is “ocean acidification” from within, by marine life. I make the reasonable assumptions that it’s now good at it, and hasn’t stopped. Any ocean acidification model that doesn’t include marine life (as player, not bystander) is thus incomplete. Expect surprises.

    You show correlation of pH with CO2, but then imply (and the IPCC assumes) causation, which I suggest is premature. If so, any extrapolation is untrustworthy.
    We don’t yet know whether the ocean is a nett source (not sink) of CO2. Also, the C20th atmospheric CO2 increase (~100 ppmv) corresponds to only a ½% change in the limestone/hardness seawater chemistry; which chemistry we know is significantly manipulated by marine life. Which is tail, and which is dog?

    • Peter, that’s a bit off. It takes considerable energy to make CO2 exit limestone. That’s why large amounts of coal/oil must be burned to heat limestone in the cement-making business — about 1 gigaJoule per ton,. actually.

      Seafloor limestone only releases its CO2 when it’s subducted into oceanic trenches deeply enough to be in contact with magma. Then, volcanic emissions can release the CO2. But that’s only a small mount of the total CO2 sequestered in limestone, which is why we have so much limestone all over, as in Florida sinkholes…

      You might want to look at the last link I put up above, Peter. Or, just email me for a detailed slide set — last name at sbcglobal dot net.

    • I neglected to mention that the dominant carbon sequestration to seafloor limestone amounts to under 300,000,000 tons per year*, while we now emit about 9,000,000,000 tons per year. Each year we fall 30 years behind. Oops.

      * AAAS Science, Canfield & Kump, vol 339, p533, 2/1/2013

  5. Euan Mearns says:

    Is ocean acidification a threat?

    The post poses a question. The answer is of course YES! Should the oceans turn to acid I dare say that carbonate and other life forms would be at great risk along with ecosystems. I do not believe that anyone commenting here is not concerned about risks to life in the oceans.

    The real question is do human CO2 emissions cause a risk to acidifying oceans and then to life. I don’t know. But I think Roger’s analysis places this in a context.

    There are comments on both sides which is good since it is not possible to have a debate if everyone agrees. Keep it civil and factual.

    For me what is missing are lab studies that show the susceptibility of carbonate skeletal life forms to “acidification” or other changes in chemistry. Field (i.e. ocean) observations on susceptibility may be attributed to a number of unconstrained variables.

    My instinct is that life in the oceans is robust to change. If it were not so we would not be here. But the cumulative impact of multiple stressors may cause populations to collapse – e.g. the Scottish North Atlantic Salmon stocks and West Scotland seabird populations. Salmon farming and factory scale sand eel fishing I believe may be the main culprits not CO2.


  6. Glen Mcmillian says:

    Sometimes the language we use is inappropriate. In this case we seem to have settled on the term ” ocean acidification ” and this leads lay people ( lay people from the perspective of marine biologists) to think or assume the discussion is actually about the pH of the oceans falling below 7.

    In actuality the actual increase in acidity is necessary to profoundly change the ecology of the seas is probably only another tenth or two tenths measured as pH at the outside.

    The oceans do not have to become ” acid” or acidic to destroy virtually everything that is useful to us that lives in them. They only have to become less basic.

    If the author does not understand this he is poorly informed to say the least in respect to marine biology although he may have extensive expertise in chemistry as such.

    Given the apparent fact that most of the regulars here seem to be professionally trained in engineering or related professions I am appalled that they do not take such possible changes in biological systems seriously. It is as if they are perfectly willing to just assume biologists are scaremongers.

    Engineers are supposed to believe in conservative design and proper safety margins.I am not an expert in marine biology but I have read enough by people who are expert to understand that another tenth or two tenths increase of acidity on the pH scale ( an inverse scale of course so the pH number will be getting smaller ) is going to play hell with marine ecosystems.

    A substantial portion of humanity depends on the oceans for protein.

    This is not going to end well.

    And for you guys who do not believe in warming- as Nate pointed out upthread you can and will pick and choose thru the evidence so as to continue to believe what you please.Brains and professional training have little to do with such beliefs so long as the evidence is not as clear as the sun at high noon on a cloudless day, and even then most people will never admit they have been wrong.

    So will those of us who do believe of course.

    But the statistics are out there . Year after year we are having higher average than normal temperatures – not higher than the year before but higher than the average over the last half century or so.We just aren’t getting the cool years we should be if warming were not occurring. We hear all about how cold it was here in the US last winter but nothing about how unusually warm it was in the far North of Asia/ Europe.

    • “In actuality the actual increase in acidity is (sic) necessary to profoundly change the ecology of the seas is probably only another tenth or two tenths measured as pH at the outside.”

      “The oceans do not have to become ” acid” or acidic to destroy virtually everything that is useful to us that lives in them. They only have to become less basic.”

      Here’s the link to an article I posted earlier. I can’t speak to its accuracy, but it appears to be well-researched and well-referenced. And it concludes, not to put too fine a point on it, that these claims are total BS.

      If you can present some hard scientific data to show that they’re not I will begin to pay attention to what you say (I am willing to be convinced). But if you can’t I will draw the obvious conclusions.

  7. Glen Mcmillian says:

    I can find as many as you like at any level of technical detail but it is getting late here and I am off to bed. I will post more and more specific ones tomorrow if anybody wants to see them.

    We don’t actually know just how bad increasing acidity in sea water may be in terms of harming organisms useful to humans but think of it like this.

    Suppose you are in charge of a very large and very complicated chemical plant and there is some junior idiot mechanic going around here and there changing adjustments on some valves at random or actually opening and closing some just because he has no better sense and wants to see what happens.

    I don’t think you will have any trouble imagining that something highly undesirable might happen to your plant and your job.

    It is not at all wise to mess with Mother Nature in such a fashion as to change one of her most fundamental physical metrics such as seawater pH. There are these things we call tipping points that when reached result in more or less unpredictable consequences.

    I think maybe you call them by some other term in engineering work but they still figure prominently into your professional work.

    Now I am not an econut trying to shut down the coal industry or the gas industry. I fully realize that doing so is an utter impossibility and that if it could be done the result would be the immediate collapse of industrial civilization and a high nineties percentile die off of all the people in rich countries. About the only people who would likely survive are third world peasants whose economies are still base on subsistence farming and a handful of technologically people in places such as the Amazon.

    I am in favor of building new nuclear power plants even though I am dead certain that there will eventually be a nuclear accident that will take out a million or more people.I aced probability theory and probability theory assures me that given time enough and nukes enough it is going to happen.Eventually.

    We are already deep into biological overshoot as a species and barring some literal miracles on the technology and cultural fronts we are going to suffer the consequences- a major die off.

    One of the primary reasons we are not going to be able to support the current and growing population long term is that we are using up and actually destroying natural ecosystems that keep us provided with food as well as one time gifts of nature such as top soil and fossil water.We are already critically short of good farmland on a world wide basis and wiping out a substantial portion of seafood production is not a risk we should run.

    But with a lot of luck and good management we just might manage to pull thru and avoid a hard fast crash since it seems that one unforeseen consequence of rising prosperity and educational levels is falling birth rates.

    If we can somehow fumble and bumble our way thru the next half century we just might avoid the worst consequences of our overshoot due to the population stabilizing and gradually falling of its own accord.

    • Glen:

      Thank you for posting some links. We make progress.

      Unfortunately, however, the links don’t contain much in the way of hard data. Taking them in sequence, the first: “Decreased abundance of crustose coralline algae due to ocean acidification” (I have the pdf) presents results which according to authors show that “The recruitment rate and growth of crustose coralline algae were severely inhibited in the elevated carbon dioxide mesocosms” which I interpret to mean that corals don’t grow well in lower pH water. Probably because of my own ignorance, however, I can’t read this conclusion into the graphs. The second, “Coral Reefs Under Rapid Climate Change and Ocean Acidification” (I have the pdf for this one too) discusses possible future scenarios as to how ocean acidification might impact coral reefs but provides no hard data, although there may be some buried in the references. The third is a newspaper article on the impending doom of Oregon oysters which provides no hard data to support the contention nor even a link to the paper it discusses, which I can’t find on the web either.

      The second paper does, however, make the following claim: “Under conditions expected in the 21st century, global warming and ocean acidification will compromise carbonate accretion, with corals becoming increasingly rare on reef systems.” Now contrast this claim with the following graph, which shows calcification rates for two component reefs of the Great Barrier Reef since the early 1600s

      The Abraham reef shows a decrease in calcification rate since 1950 that could reflect the impacts of decreasing pH, but it also shows an increase over the preceding 300+ years, when pH was also thought to have been decreasing. The calcification rate at the Britomart reef shows no significant change since the early 1600s. Do these results demonstrate a connection between ocean acidification and reef growth? (I’ll leave that question hanging).

      The data are from.

      Lots of other reefs for you to play with. Incidentally, this is what I call “hard data”.

  8. Hugh Sharman says:


    I am mostly with Nate in this one.

    I do not even pretend to have any expertise or even deep knowledge in this field. But Roger’s curves, especially those showing a strong correlation between atmospheric CO2 concentration and ocean pH give me the heebeejeebies.

    It seems unarguable that levels of atmospheric CO2 are at highs not seen in the geological record for millions of years and that these highs are anthropogenic in origin. This, and the simple evidence of our eyes, convinces me that in the short 15,000 years of the Holocene, and the effective existence and flourishing of homo sapiens, we are well justified in calling this inter-glacial the Anthropocene.

    Anyone with even a passing interest in geology is well aware of the many, sudden, mass extinctions of species that have occurred on this wonderful and beautiful speck of life, floating so serenely within the Milky Way galaxy, amongst billions of other galaxies. We may, after all, be the only planet in the whole universe transformed by life. Viewed against geological time, the Pleistocene will do, we humans are transforming the planet and with it life on earth in a millisecond of geological time.

    As it happens, I am not a misanthrope. But I am concerned that the Anthropocene will end with a population collapse caused by over-population and natural resource exhaustion, long before AGW is likely to seriously affect civilisation and certainly before the next inevitable ice age which must surely be rather close. The 5° C warmer, seawater 5 m higher, Eemian only lasted 15,000 years or so (certainly not driven by CO2). By some measures, I would judge the beginning of Holocene to be 15,000 years ago – or even earlier.

    If humanity survives that long, the next ice age will be curtains for civilisation of course! If there are any human survivors, they will struggle to do so because of the depletion of the natural resources that we as a species inherited at the beginning on the Holo/Anthropocene!

    The good and much mocked Rev Malthus may have the last laugh, after all!

    • Euan Mearns says:

      Hugh, I think the main reason for Roger’s post was to show that existing changes in ocean pH are minuscule. If these are causing the changes to ocean life some studies suggest then we are well and truly **d. Alternatively the changes to ocean life may be down to some other cause(s). I have not read the studies Glen posts yet.

      The oceans are extremely complex, stratified chemically, by temperature and by density.

      One thing I think is pretty certain, and that is CO2 emissions are going to continue to rise unabated for a long time to come, until resource constraints kick in.

      • Glen Mcmillian says:

        ”One thing I think is pretty certain, and that is CO2 emissions are going to continue to rise unabated for a long time to come, until resource constraints kick in.”

        I agree completely and totally.

        My perspective speaking as a professional in my field of agriculture is that we are pretty well damned if we do and damned if we don’t no matter what we do or do not do in terms of our politically and economically viable options.We aren’t going to quit burning coal any more than we are going to give up eating.Civilization as it exists today is utterly dependent on fossil fuels and it is by no means certain that it is ever going to be possible to maintain anything even remotely resembling our current way of life over the long haul unless the population shrinks to a small fraction of what it is today and we learn to use our remaining depleting resources very frugally indeed while gradually switching to nuclear power and renewables and gradually learning to live well on a rather minor fraction of the per capita energy we consume in rich societies today.

        My perspective as a professional farmer is informed by the basic sciences that are the foundations on which the applied art and science of agriculture are built. These are biology, chemistry, geology, geography, climate and so forth.I am not truly expert in any of them anymore that civil engineer is apt to be truly expert in physics – in comparison to a physicist- or in higher mathematics – compared to a mathematician. But like the engineer I generally know enough to make informed decisions in relation to my own work.

        I am not an expert in either medicine or law but I have to depend on the judgement of people in those fields in making truly critical life decisions. I have very little respect for either profession because I cynically think most of the actual practitioners in both of them are money grubbing opportunists who do not really give a damn about the people they talk about serving.Nevertheless I do not believe they are lying to me and to every body else when they make their professional judgements known to the public.

        My dentist is a money grubber par excellent who happily charges a poor laborer two weeks take home wages for an hour of his time at least once a day and he customarily charges at least about five to six times as much per hour NET to himself as his patients typically earn. But if I bitch about the cost of a cavity or a root canal he rightly and honestly points out that if I would brush and floss with greater regularity and energy and eat less sugar and drink less soda pop I would hardly ever have a cavity- and he is telling me the truth.

        Any person who thinks the vast bulk of all our educational and professional organizations are liars and incompetents just out to collect grant money and willing to constantly unethically fudge their data is simply as naive as a small child when it comes to understanding what the scientific and higher educational establishments are all about.

        Physics and mathematics are the basic sciences that underlie the profession of engineering. Does anybody here know any engineers who think the professors of physics and places such as the University of Virginia or Harvard or MIT or Yale or any of the worlds accredited and recognized universities for that matter are incompetent money grubbing lying scumpbags just out to get some grant money and willing to trade their personal and professional integrity for that money?

        Why should I being a professional myself discount the grave worries and warnings being put forth daily by the people in the fields that inform my own?

        If you are running a chemical plant and the pH of your product falls unexpectedly (perhaps due to varying quality of your raw materials for instance) by a tenth towards stronger acidity there is for sure going to be a mechanism available to you to buffer the product and put the pH right again. BUT the buffering system might lack sufficient capacity and adding to much buffer in the event the input materials are unsuitable might gum up the works badly in terms of the finished product.

        Now in the case of our pumping co2 into the seas via burning fossil fuels- well there may or may not be enough resilience in the natural ecosystems to handle the extra acidity in most cases. There is substantial emerging evidence that there are some key life forms near the bottom of ocean food chains that are already having a tough time dealing with the increased acidity.

        THe whole oceans need not become noticeably more acidic to wreak havoc with marine ecosystems to such and extent that the consequences could be catastrophic in human terms.Being a working farmer I know a good bit about machinery as well as biology and I can take an ordinary pair of pliers and disable twenty ton bulldozer in ten seconds flat by pulling out a couple of wires or crimping a fuel line.

        One broken link in a tow chain means you have lost your tow. Biological systems share this vulnerability to disruption with machinery.The loss of the nursery environment (for example) supplied by coral reefs can without a doubt wipe out some commercial fish species if we lose the coral reefs- and not all of them- just the ones where that species of fish get started in life.Once such a loss is incurred there is simply no telling what additional undesirable feedback effects might come into play.

        I should not need to point out that we don’t have any system available to buffer the waters of the oceans and that given the almost unimaginable size and cost of any system that might conceivably work we are NEVER going to have one.

        It is highly probable that we will never even be able to buffer the amount of water in a single major bay.

        I want to add one other pertinent observation. We humans are evolved creatures with brains programmed by our evolution to think in terms of time frames that were the most critical ones to primitive men and our emerging modern model. This means we are almost unable to think at a visceral level in terms much longer that minutes,hours, days, and years. A decade is just about forever in the eyes of a human being unless he has already lived to at least middle age.

        BUT in terms of the time frames that are relevant to natural systems such as climate a decade is a mere eye blink. Nature in terms of human perception moves at less than a glacial pace.In geological, climatic, and biological processes a thousand years might be usefully thought of as a few seconds or maybe a minute to a man.

        There is a mountain behind my house and I can drive my old truck halfway up it before the temperature gauge starts to climb enough to see it move. By the time I get to the top however it has moved a good way toward the red zone.If I never went more than halfway up the mountain I would never realize the engine is heating up slowly but surely beyond its normal operating temperature.

        So far as I know just about every physicist who has looked at the black box problem and climate and co2 levels has come to the conclusion that barring unforeseen negative feed back processes stopping warming the world is going to get to be a hotter and hotter place. I have not yet run across any work by any respected biology professor who thinks ocean acidification is nothing to worry about.

        We have a choice as to who we will believe is cherry picking data in terms of climate and other critical issues such as ocean acidification.

        I have made mine and it is not with think tanks and organizations with skin in the business as usual game.Others of course are free to believe as they please.I am sticking with the vast majority of experts in the relevant fields.I don’t believe in gigantic conspiracy theories except PERHAPS when they are crafted and implemented by big business to keep the more gullible individuals among us faithfully marching along as useful idiots with a vote and a keyboard.

        Anybody thinks the management of the worlds major banks and other gigantic corporations has his best interests at heart is a pathetic fool.

        The fossil fuel industries and major banks and motor industries and construction industries are all far far more interested in short term returns than in long term stability and the health of the natural world that keeps us alive. The vast majority of the individuals in these industries are of course well intentioned and honest but ignorant of the consequences of their life’s work.They don’t know and they don’t want to know because as individuals their very survival and prosperity depend on that paycheck and that capital gain and that dividend check.

        But in the quiet rooms where the carpet is deep and everybody is wearing five hundred dollar shoes and strategic decisions about the long term future are made- well in those rooms decisions are made to fund sites and organizations that exist in large part to keep the fools in the dark.

        At one time I used to take the word of such organizations as the Heritage Foundation seriously myself.Back then I still had a young optimists faith in technology and had no doubt we agriculture professionals would always be able to laugh at the biologists who talked about the good Reverend Malthus and starvation.

        But I gradually came to recognize that what they had to say does not mesh well with the reality I was observing and started digging. I started by rereading later editions of the basic biology texts I studied as an undergrad and went from there.The more I have dug the worse the big picture looks.

        The only bright spots really worth mentioning are, one , that birth rates are falling fast and that we might just see a population decline without a die off in the classical biological sense in most parts of the world.Two that the technology of renewable energy and nuclear power are moving ahead fast and that we just might possibly between the two get by ok in combination with the third. The third is progress in using energy and other resources more efficiently.If ” business as usual” lasts a few more decades we will have net zero energy houses and battery electric cars is substantial numbers just for a start.If we make it thru the fossil fuel and climate bottleneck conservation and efficiency are going to be the keys .

        • Hugh Sharman says:

          Good stuff, Glen! Our tiny brains are not designed (or evolved, if one prefers to keep the toxic word “designed” out of the issue) to think and plan on geological timescales. You only have to listen to the history of events 100 years ago and look around the world today to see that politically, mankind has not learned a thing despite his huge inventiveness.

          If anything, the (human) world is in more danger now than even the day the Arch-duke was assassinated.

          Mind you! This does not alter the simple fact that many “warmists” and “ocean acidifiers”, who are just as badly qualified, scientifically as you and I, are whipping up hysteria because it suits their pockets and their careers so terribly well. It was always so!

          I am satisfied that under Euan’s monicker, and with the well-mannered and erudition of most of his contributors here, Energy Matters will not turn into another foaming-at-the-mouth, single-issue, anti-AGW shouting blog.

    • Hugh: The “strong correlation between atmospheric CO2 concentration and ocean pH” occurs because I calculated pH from CO2 values.

      As shown in the third figure the observed correlation isn’t all that good. The R^2 value of 0.47 in fact implies that less than half of the pH decrease at ALOHA over the period of measurement can be explained by increasing atmospheric CO2.

      • Glen Mcmillian says:

        I suppose some folks think the Smithsonian is also part of a grand conspiracy to hoodwink us all and that this august institution doesn’t care about losing it’s reputation when the ” truth ” comes out and warming and acidification turn out to be trivial issues.SARCASM light is ON.

  9. A C Osborn says:

    Euan, I am sorry, but I can’t take any more of this kind of ignorance any longer.
    Here is the offending paragraph.

    “But the statistics are out there . Year after year we are having higher average than normal temperatures – not higher than the year before but higher than the average over the last half century or so.We just aren’t getting the cool years we should be if warming were not occurring. We hear all about how cold it was here in the US last winter but nothing about how unusually warm it was in the far North of Asia/ Europe.”

    If Glen was to do just a little research on non warmist sites he would realise that the Hottest Month/Year statements are in actual FACT nothing but the artifact of the ADJUSTMENTS that are made to the ACTUAL REAL LIFE TEMPERATURE READINGS by the Government organisations putting out the data and statements.

    If he did some research in to the subject he would find that they actually admit it as well, the worst culprits being NCDC/GISS and Australia’s BOM.
    Even the people working on the Berkely BEST data say and I quote “If you want to know what a historical temperature is look at the RAW data, if you want to know what WE THINK IT SHOULD HAVE BEEN look at the BEST final output.

    If he doesn’t belive what I am saying perhaps he would like to go and see for himself just how much warmer it was in the USA in the 1930s than it has been in the last 20 years.

    If he thinks it is only cold in the US and yes it is Record breaking cold he should have a look at Australia, where it has just snowed in Victoria and Bombala, or how about Italy where they are talking about a “Year without summer”, or 6″ Hail Stones in Osk, or October like temperatures in Portugal, or a foot of Hail in Spain, or the coldest in Serbia in living memory, or how about Manali India where they are saying things like this ““I’ve seen 83 summers and winters in my life but never witnessed such summer when my family is forced to sleep under quilt in June and July,””.

    If that is isn’t enough real world statements of how cold it really is I am sure I can find plenty more Head lines to go with them which counteracts the Propaganda statements being put out to support the Presidents “Climate” position.

  10. Roger Andrews says:


    Running out of space higher up. This is in response to your comment of August 3, 2014 at 6:12 am

    The Science article you link to states that “An increasingly acidified Pacific Ocean is dissolving the shells of tiny marine snails that live along North America’s western coast.” and that “The waters probed during this study, known as the California Current, are a hot spot of ocean acidification because of coastal upwelling, which brings naturally acidic waters to the surface, where they are made even more acidic by greenhouse gas pollution.”

    I did a Google search to see if I could find any information on the pH of upwelling seawater along the California coast and came up with some from Scripps:

    Scripps broadly agrees with Science: “Low-oxygen and low-pH events are an increasing concern and threat in the Eastern Pacific coastal waters, and can be lethal for benthic and demersal organisms on the continental shelf. The normal seasonal cycle includes uplifting of isopycnals during upwelling in spring, which brings low-oxygen and low-pH water onto the shelf.”

    So far so good. But how low is the pH of the upwelling water? Scripps supplies this plot for the Del Mar site off San Diego. Sea surface pH normally hovers around 8, but during upwellings it drops at least into the low sevens and may even drop below seven (i.e. become truly acid) in some cases. Clearly the impacts of CO2-induced pH decreases on marine life along this part of the Pacific coast are insignificant compared to the pH decreases caused by the upwellings.

    Once again you are invited to post data in rebuttal. Or anyone else for that matter.

  11. Greg M says:

    A slightly different perspective on the US Pacific NW situation regarding the mainstream media acidification articles:

  12. Just to add another link to reduce everyone’s ignorance:

    From the scientific report I quote this: “Temperature increases and acidification alone may irreversibly destroy coral reefs, the most species-rich marine ecosystems in the Ocean, within 50 to 100 years if positive action is not taken now.”



    • A C Osborn says:

      In that case perhaps you could explain why in recent times more Coral has been severly bleached by Cold Temperatures than by warm and more Manatees killed by cold than warm?
      Also that the Great barrier Reef and other corals suffers more damage from human Sun Cream than from warm water?

  13. Nate Hagens says:

    Heres a short article about Ocean conference held at White House last month. I think the first response and moderator comment is very informative about higher CO2 in the past, but the pace of silicate weathering causing calcium carbonate ions to still be plentiful.

    I post the exchange here.
    “I have a problem with the theory that molluscs and corals are suddenly at risk from ocean acidification due to CO2 at 400ppm (though I don’t doubt that they are threatened by many other man-made risks).

    These two life-forms evolved over the last half billion and quarter billion years respectively. Over almost all of that time period, atmospheric CO2 levels were much, much higher than they are today.

    “Simple chemistry” would imply lower pH levels in the geologic past, far below what we’re likely to cause with CO2 emissions. And yet, molluscs and corals survived and are still with us.

    I can’t explain it.”
    Moderator Response:

    (Rob P) Actually the basics are rather straightforward. As far as many marine calcifiers are concerned, it is calcium carbonate saturation state that poses the strongest control on shell building – not the excess hydronium ions (low pH). Carbonate ions are one of the building blocks of calcium carbonate shells/skeletons, and one of the chemical reactions that takes place when CO2 dissolves into seawater is the lowering the carbonate ion concentration (technically activity).

    Change in atmospheric carbon dioxide on geological time scales allows enhanced chemical weathering of rock to supply carbonate and bicarbonate ions back to the ocean. Furthermore, the total dissolved inorganic carbon (DIC) in the ocean undergoes a large increase due to the increased weathering that accompanies the ramped-up hydrological cycle (lots more rain dissolving lots more minerals into the ocean).

    The net effect is an ocean very hospitable to calcification despite the low pH. The Cretaceous Period (the ‘K’ symbol in your graphic) is a classic example. Cretaceous is derived from the Latin word for chalk, as in the huge chalk deposits that formed during that time. These chalks deposits, such as the White Cliffs of Dover, are of coccolith shells – tiny marine plankton that thrived in the Cretaceous. Ginormous shellfish, Rudists, were the dominant reef builders of that time too.

    During times of geologically-rapid increases in CO2, such as now, the ocean carbonate system can’t keep up and the oceans become corrosive. Carbon dioxide dissolves rapidly in the ocean, but there is an insufficient increase in the rate of chemical weathering because it takes millennia for the enhanced rainfall to flush sufficient carbonate & bicarbonate ions back into the oceans. The sum effect is that ocean pH and calcium carbonate saturation decline in tandem.

    This is why ocean acidification (corrosive seawater) only develops with geologically-rapid increases in atmospheric CO2, but doesn’t otherwise. I’ve simplified this a bit, e.g. leaving out dissolution of carbonates on the ocean floor during periods of lowered atmospheric CO2, but that’s the general picture. SkS will have rebuttals to this common misconception in the near-future.

  14. De’ath, G., J.M. Lough, and K.E. Fabricius. 2009.
    Declining coral calcification on the Great Barrier Reef.
    Science, Vol. 323, pp. 116 – 119, 2 January 2009.

    Reef-building corals are under increasing physiological stress from a changing climate and ocean absorption of increasing atmospheric carbon dioxide. We investigated 328 colonies of massive Porites corals from 69 reefs of the Great Barrier Reef (GBR) in Australia. Their skeletal records show that throughout the GBR, calcification has declined by 14.2% since 1990, predominantly because extension (linear growth) has declined by 13.3%. The data suggest that such a severe and sudden decline in calcification is unprecedented in at least the past 400 years.

    Here’s a plot of the backup data:

  15. A C Osborn says:

    How mankind really damage the Barrier Reef Coral.

    ” Four commonly found sunscreen ingredients can awaken dormant viruses in the symbiotic algae called zooxanthellae that live inside reef-building coral species.

    The chemicals cause the viruses to replicate until their algae hosts explode, spilling viruses into the surrounding seawater, where they can infect neighboring coral communities.

    Zooxanthellae provide coral with food energy through photosynthesis and contribute to the organisms’ vibrant color. Without them, the coral “bleaches”—turns white—and dies. ”

    Along with damage from ship’s oil, polution and physical damage

    Note this statement “Another scourge of the reef is bleaching, where corals have died in large numbers. This phenomenon is not exclusive to Queensland’s Great Barrier Reef, but has been observed on reefs throughout the world. It is thought the bleaching has been caused by rises in water temperature related to the El Nino effect, although the evidence is not conclusive.”

    Note the “not conclusive” and this is the Australian Government.

  16. Pingback: Links 8th August 2014 | AQONEMAKI

  17. James W. Murray says:

    It’s such a waste of time to get involved in responding to blogs. Because of the time change, by the time I read something I’m already 10 pages deep in responses. But I have to say, your blog entry on Ocean Acidification (OA) reminds me of the “Republican Brain” by Chris Mooney. A great book, which is not really about or limited to Republicans. Reading this OA entry gave me the same feeling I have when reading op-eds by so many peak oil skeptics. Lots of misrepresentation of the data and what we know.

    1. Open ocean pH is going down after being incredibly stable at 8.1 to 8.2 for several million years.
    2. Its going down fast, even compared to what we know about paleo pH changes. The rate of change appears to be unprecedented.
    3. pH is a log scale and the change in H+ concentration is significant (in only 30 years).
    No chemical oceanographer would claim the ocean will be come acid (pH <7). More acid means pH is going down and H+ is going up.
    4. If you really want to make the change look small, plot on the full pH scale of 0 to 14. What's your point? pH does not have to become less that 7 for there to be problems.
    5. There may be biological impacts of H+ itself but the big concern is the decrease in concentration of CO32-.
    6. Much of marine biology makes shells of CaCO3 (coral reefs, coccoliths, foraminifera, pteropods). The solubility of CaCO3 is determined by the concentrations of Ca and CO3 but as Ca is a major ion in seawater and essentially constant, it is the concentration of CO3 that matters. As pH goes down, CO3 goes down even faster. Experiments show that SW does not need to become undersaturated wrt CaCO3 for organisms to be endangered. Studies of pteropods in the North Pacific show that they are already being impacted.
    7. Pteropods are a major food source for salmon. Coral reefs are the charismatic marine CaCO3 structures. The impact of OA has the potential to impact the whole marine food web.

    Is this really an experiment you'd like to see us conduct?

    8. There is natural OA when deep water, low in O2 and high in CO2, is upwelled. Wind driven upwelling on the coast of Oregon and Washington is an example. Even there, about 25% of the increase in dissolved inorganic carbon (DIC) was acquired when that water was back at the sea surface as an anthropogenic OA contribution.


    • Euan Mearns says:

      Reading this OA entry gave me the same feeling I have when reading op-eds by so many peak oil skeptics. Lots of misrepresentation of the data and what we know.

      Jim, I am a former principal of The Oil Drum that was once the World’s leading peak oil blog (by far) and Energy Matters is in fact a peak oil blog – trying to obey the rules of knowledge and understanding evolution.

      I hope you don’t mind me pointing out to my readers that you are posting from a .edu email. Academic opinion is I’m afraid held in declining esteem. No personal sleight intended, but you will have to back up some of your claims here with data. I assure you we are ready and willing to listen to well argued and backed up claims and to modify our views accordingly. And so for starters:

      1. Open ocean pH is going down after being incredibly stable at 8.1 to 8.2 for several million years.

      Evidence and veracity of evidence please.

      2. Its going down fast, even compared to what we know about paleo pH changes. The rate of change appears to be unprecedented.


      It strikes me that ocean pH is not uniform today either spatially or vertically and that a change in pH of 0.1 units is rather small. And so to make the claims you make would require some incredibly precise proxies measured in huge amounts of paleo oceanic records.

      I’m intrigued to know how this is done and how reliable the data are. Euan

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