Climate Science Glossary

Term Lookup

Enter a term in the search box to find its definition.

Settings

Use the controls in the far right panel to increase or decrease the number of terms automatically displayed (or to completely turn that feature off).

Term Lookup

Settings


All IPCC definitions taken from Climate Change 2007: The Physical Science Basis. Working Group I Contribution to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, Annex I, Glossary, pp. 941-954. Cambridge University Press.

Home Arguments Software Resources Comments The Consensus Project Translations About Donate

Twitter Facebook YouTube Pinterest MeWe

RSS Posts RSS Comments Email Subscribe


Climate's changed before
It's the sun
It's not bad
There is no consensus
It's cooling
Models are unreliable
Temp record is unreliable
Animals and plants can adapt
It hasn't warmed since 1998
Antarctica is gaining ice
View All Arguments...



Username
Password
New? Register here
Forgot your password?

Latest Posts

Archives

Acidification: Oceans past, present & yet to come

Posted on 31 March 2011 by Rob Painting

Through the burning of fossil fuels, humans are rapidly altering the chemistry of the global oceans, making seawater increasingly more acidic. Most attention to date has focused on what we might expect in the years to come, and rightly so, many studies have shown that the seas of the future are likely to be corrosive to shell-building marine life. Some areas, such as the Arctic, might even reach a corrosive state within a decade. But, knowing that ocean acidity has increased by almost 30% since the beginning of the industrial civilization, has the change so far already had an effect on marine life?

Talmage and Gobler 2010 sought an answer to this question by examining growth and shell formation in two shellfish species, the Northern Quahog hard clam and the Bay scallop. In lab experiments they grew juveniles in seawater at various levels of pH representing the global average for specific points in time, pre-industrial (250ppm atmospheric CO2), modern day (390ppm), and CO2 levels expected by the year 2100 (750ppm) and 2200 (1500ppm) under moderate business as usual scenarios.

Figure 1 - Microscope image of Northern quahog hard clam (Mercenaria mercenaria) under various levels of CO2 at 36 days old. A= individual juvenile at each CO2 level. B= side cross section of shell at each CO2 level. C= hinge close-up at each level. 

Figure 2- Microscope images of 52 day old Bay scallop (Argopecten irradians) grown under different levels of CO2. A= Individual juvenile at each CO2 level. B= Close-up of outermost shell for each juvenile at each CO2 level.

Not surprisingly, the 750ppm and 1500ppm states induced shells that are thinner, smaller and weaker, as well as low rates of survival for juveniles. In contrast, under pre-industrial levels (250ppm), the improvement in health and survival was significant. Shells were much larger, thicker and more strongly built than under modern day conditions, and survival rates were double that of modern day (40% vs 20% after 38 days for the hard clam).

Even under ideal conditions, mortality is high among juvenile shellfish populations, and this study reveals that not only does the death rate increase along with seawater acidity, the shells are smaller, thinner, more fragile and internal organs are less healthy. Not exactly desirable traits for a shellfish. 

These experiments suggest that ocean acidification has already had a negative impact on shellfish populations over the last two centuries. Alongside pollution and increased nutrient run-off from industrial farming, ocean acidification might be yet another factor in the rapid decline of wild shellfish populations

0 0

Printable Version  |  Link to this page

Comments

Comments 1 to 34:

  1. Scary, isn't it?
    0 0
  2. Mike, no idea why the authors chose that value, and (without checking) how far back in time that would be. Older papers had immediately pre-industrial at 260-280ppm. But whatever the case may be, the experiments indicate things have already taken a turn for the worse.
    0 0
  3. 2, Mike, 3, Rob, The authors of the study used (emphasis mine) "larvae grown under near pre-industrial CO2 concentrations (250 ppm)"... that is, the statement isn't that pre-industrial levels were 250 ppm, but rather that 250 ppm were used as the benchmark to simulate growth at about pre-industrial levels. Reading the materials and methods section of their paper, it seems that coming up with a sea-water-CO2 "soup" is not as simple as mixing ingredients in the right proportions. They got a medium which they considered suitable, then measured the CO2 levels in that medium (in fact, the actual levels were 247 ±6 and 244 ±4) to see what they were working with. Futzing around to get it to exactly 280 ppm probably wasn't worth the time and effort, nor truly relevant to the study.
    0 0
  4. Mike at 2 They used 250 ppmv because it is a nice even number. They should have used 400 ppmv rather than 390 ppmv. In science exp's one always avoids "weird ball" numbers.
    0 0
  5. h pierce#6: "In science exp's one always avoids "weird ball" numbers." That's one possibility. Here's another: Scientific measurements of levels of CO2 contained in cylinders of ice, called ice cores, indicate that the pre-industrial carbon dioxide level was 278 ppm. That level did not vary more than 7 ppm during the 800 years between 1000 and 1800 A.D. But maybe you have a good idea. For the immediate future, let's avoid weirdball numbers: Pi is now and forever set to 3. And so is e. Makes things much simpler.
    0 0
  6. According to William Howard, a marine geologist, the current rate of acidification is about 100 times faster than the most rapid events in the geological past (http://www.scientificamerican.com/article.cfm?id=ancient-ocean-acidification-intimates-long-recovery-from-climate-change) It is estimated that By 2100 pH will have fallen from its present 8.069 to 7.824. The speed and magnitude of decline makes it impossible for calcifying animals to adapt. As pH falls, so does aragonite and other calcite saturation. That saturation is essential for corals, plankton and other marine calcifiers to make protective shells without which they can not survive. By 2050, Pteropods (Thecosomata) will be extinct and most coral reefs dangerously vulnerable to predators. These changes pose two problems: a serious break in the food chain and loss of marine habitat for water breathing animals. These problems are exacerbated by persistent overfishing and ocean pollution. Both are occurring as a result of human activity and population growth. Both are likely to result in loss of an essential food source and the extinction of many marine animals by 2100. Why? Because we prefer to pursue BUA and short term profit rather than a sustainable future.
    0 0
  7. There are a potential flaws in the procedure: They medium was not properly buffered. They should have added some ground up sea shells or dolomite lime. The buffer system of the ocean contains soluble bicarbonate and insoluble calcium and magnesium carbonates. As long the insoluble carbonates are present, the pH can not fall ca 8. Since the medium was not buffered properly, the production of certain micronutrients of the phytoplankton may have been affected. ATTN: Sphaerica Did they actually measure the pH of the medium during the experiments? It appears they computed the pH at the higher levels of CO2 and didn't actually measure it.
    0 0
  8. h pierce, On pH, from their paper:
    Multiple daily measurements of pH (calibrated prior each use with NIST traceable standards, ± 0.002, Orion Star Series Benchtop pH meter; Thermo Scientific) indicated experiment beakers maintained a constant pH level throughout all experiments (<0.5% RSD within treatments).
    I see nothing that says this was only done for lower-CO2 samples, or why they should do so. I'm also unsure if your buffering argument holds, since it is unclear in the paper whether they did or did not address it directly in any way. They did use actual sea water which presumably would have the right general levels of everything, and at least in our scenario, the levels of buffering agents in the actual ocean are not changing appreciably over time, since CO2 is entering the ocean through the atmosphere rather than through geologic weathering processes. Their pH did fall below 8 (8.171, 8.052, 7.801 and 7.532 respectively for 250 ppm, 390 ppm, 750 ppm and 1500 ppm).
    0 0
  9. h pierce, You seem to think that you have some valid points. And maybe you do-- a good means of determining whether or not they have merit or of consequence, is to write a comment to the journal. Personally I do not find comfort in these findings as they corroborate previous research. There are no free passes for doubling or trebling atmospheric CO2 levels in a very short time. To think otherwise is naive and going against a whole lot of science, both empirical and theoretical.
    0 0
  10. Albatross at 11 Ocean Buffer System Formation of Carbonic Acid CO2 + H2O---->H2CO3 Neutralization of Carbonic Acid H2CO3 + CaCO3--->Ca2(HCO3) Dolomite is a mixture of calcuim and magnesium carbonates and is used to "sweeten" soil. A solution of freshly-preparded NaHCO3 has a pH of ca 8. A soluble bicarbonate is unstable and decomposes to carbonate.The pH increases to ca 10.
    0 0
  11. H Pierce @ 9 - The buffer system of the ocean contains soluble bicarbonate and insoluble calcium and magnesium carbonates. As long the insoluble carbonates are present, the pH can not fall ca 8. This is nonsense. Do you want to try again explaining what you mean?.
    0 0
  12. I just crushed chalk into water and shoke the mixture vigorously for ca 1 minute. After the solid chalk had settled, I then measured the pH of the supernatant with a Macherey-Nagel (Product No 92110) pH indicator strip. The pH was 8.
    0 0
  13. Albatross & Sphaerica - H Pierce is confused when he refers to the "Ocean buffer system" The carbonate buffer typically referred to, are the chemical reactions which take place to inhibit the change in pH. For instance see the diagram below: I've yet to find a graphic which adequately describes the process, but bear with me: Equation 2 Carbonic acid easily breaks down releasing excess hydrogen ions and drives the pH of seawater down (pH being a measure of the concentration of hydrogen ions. More hydrogen ions = lower pH ). Equation 3 Here's where the buffering part kicks in, some of the excess hydrogen ions combine with carbonate ions to form bicarbonate ions. This last step serves to buffer the acidification because it reduces the concentration of hydrogen ions. So without this last reaction, the pH would be lower. He seems to be referring to geological processes which increase alkalinity (often balancing out volcanic CO2 output) which takes place over the timescale of tens of thousands of years.
    0 0
  14. H Pierce - They medium was not properly buffered. They should have added some ground up sea shells or dolomite lime. Altering the pH of the seawater kinda defeats the purpose don't you think?.
    0 0
  15. @ H Pierce the situation is a little more complicated with seawater than what you have modelled with your simple experiments with CaCo3. There is other buffers at work in sea water. Sulphates, borates and organics from life. The experience of aquarium keepers with salt water is that attempts to buffer sea water aquariums with ground up shells is that this is not workable as the pKa shifts from about 8.1 to 7.6 with simple addition of CaCO3 powder over shorter and shorter periods. In short adding base but shifting the kPa to lower values is counter productive. A commercial buffer is used with a properly mixed set of buffers at about 8.1 pKa is long term workable.
    0 0
  16. Rob at 15 and 16 Equation 2. Carbonic acid is a weak acid and produces little H ions in water at 20 deg C, ca 0.0001 moles per liter . Also only about 1% of the dissolved CO2 is converted to carbonic acid. Equation 3 Bicarbonate releases very little H ions. The second ionization constant is 4.9 x 10 exp-11 for K2=(H)(CO3)/(HCO3) The diagram is misleading. It I were doing the experiment, I would have added a bed of clean marble rocks and quartz sand.
    0 0
  17. Paul at 17 I was trying to keep it simple. Although the ocean floor and beaches are littered with shells, I recall that shells contain small amounts of calcium silicate that acts as cement to give them strength and a more compact structure. Thus the shells don't release carbonate easily. Unless they are ground to micro bits by pounding surf from a big storm. Another objection to the experiments is that poor little larva were given "pH shock treatment". In the real ocean any decline in the pH will occur very slowly. It is quite possible the species will adapt overtime to the new conditions.
    0 0
  18. H Pierce @ 18 - Carbonic acid is a weak acid and produces little H ions in water at 20 deg C So how do you think the pH of the global oceans is falling?. What's causing all those hydrogen ions to disassociate from seawater?. Just wondering, because thus far you haven't made much sense. Also only about 1% of the dissolved CO2 is converted to carbonic acid. Carbonic acid & dissolved CO2 make up less than 1% of dissolved inorganic carbon in the ocean. If you are suggesting that carbonic acid itself is what ocean acidification is about, then sorry that's just a fallacy. The oceans are becoming more "acidic" because the concentration of hydrogen ions are increasing, and because it's an inverse logarithmic scale, pH falls. Bicarbonate releases very little H ions See my comment at @15 which accompanies the graphic. You have that back-to-front, the excess hydrogen ions combine with carbonate ions to form bicarbonate. This carbonate buffering process is what causes problems for calcifying marine life, because it reduces the carbonate "building block" which many marine organisms use to build their shells/skeletons. For any interested readers I refer you to Ocean acidification due to increasing atmospheric carbon dioxide - The Royal Society 2005. Click on the pdf on the top right-hand corner. It thoroughly covers the subject, without being incomprehensible.
    0 0
  19. H Pierce - In the real ocean any decline in the pH will occur very slowly Nope, that's wrong too. The mean ocean pH can only change slowly as new carbon is to the global inventory, however on local scales there can be large fluctuations as dissolved inorganic carbon is "shuffled" about the ocean. A classic case is the equatorial Eastern Pacific (west coast of the Americas) where the La Nina/El Nino phenomenon occurs. In a La Nina phase, plumes of cold water with high levels of dissolved CO2 reach the surface ocean from down deep. When they do, surface pH can fall dramatically. It's why coral reefs in the area are so poorly developed, patchy in coverage, weakly cemented and prone to high rates of bio-erosion. A useful way of thinking about it, is to liken it to the mean global surface temperature. That doesn't change much, but on local scales, and in short time-frames, there can be significant fluctuations. All marine life have the ability to adapt to fluctuations in ocean pH, and tolerance thresholds will of course vary , but if they couldn't they simply wouldn't survive. It's when the ocean pH falls and stays that way, that problems arise.
    0 0
  20. h pierce, The experiment was well designed and meaningful. The results are therefore meaningful and should be taken as a warning that we are destabilizing too many things at once through our callous actions, and in a very dangerous way that is going to come back to haunt future generations.
    0 0
  21. H peirce I think your problem here is that in pure water only 1% of carbonic acid releases H+. This forms a solution about pH 5. The Ocean is about pH 8.2 so most of the new carbonic acid immediately dissociates an H+ ion. The dissociation is proportional to the pH (keeping in mind pH is a log function so 5-> 8 is 1000 times) and the Ocean is basic. Skeptics need to understand the background before they try to explain chemistry to other people.
    0 0
  22. Shorter H.Pierce: "It is quite possible things will be OK." I'm trying to compare that to my mindset when, say, boarding an airplane. Hmmm
    0 0
  23. I think Michael nailed where the confusion comes from. We often hear this weak acid/strong acid argument as if the pH doesn't matter to dissociation of carbonic acid. At pH 8, carbon acid might as well be HCl as it dissociates almost completely. I've been caught out several times by this fallacy as well. I have also heard this argument about CO2 and carbonic acid before as well and I couldn't figure out where it came from. Fact is, we can't usually discriminate between dissolved CO2 and carbonic acid by measurement. Empirical pKas are determined assuming CO2(aq) and carbonic acid are essentially the same thing. I know Gobler pretty well. If you guys have questions about setup of this experiment I can probably get him or Talmage to respond.
    0 0
  24. What effect, if any, does carbonic acid have on the presence of iron in a form which can be utilized by plankton and promote their bloom? Is low iron concentration in the Southern Ocean due to carbonic acid (presumably stronger in cooler waters), lack of upwelling of water from the seabed, or some other reason?
    0 0
  25. @Agnostic...The Southern Ocean is Fe limited because it gets most of it's nutrients from upwelling of very old deep water. Fe is not very soluble in the ocean under current pHs - it tends to complex with particles and gets removed to sediments over time. As deep water ages, Fe is slowly stripped from water by this process. When it rises to the surface there is consequently a definict of Fe rlative to nitrate, phosphate and silicate. The Fe gets used up by algae before the other nutrients, leading to Fe limitation and what are called High Nutrient Low chlorophyll (HNLC) conditions. In other regions that receive river water, release of Fe from sediments or dust, Fe is not so limiting and thos conditions don't ocur. I think that general picture is unlikely to change until pH drops quite a bit, and then it could take quite a while for any effect to be observed as you'd have to see that pH change at depth and aloow time for the slow processes I referred to respond. I know someone has recently done a calculation on the effect of pH on Fe availability. I'll see if I can find it. I'm sure it comes with a lot of caveats.
    0 0
  26. Agnostic @ 26 - Steve Baines may be referring to this paper Effect of Ocean Acidification on Iron Availability to Marine Phytoplankton. I don't have a copy, but it is discussed in sufficient depth here.
    0 0
  27. Paper above applies to the economically important species - and yet only one of the species - does not provide the basis for good general conclusions. How - in general - the organisms react to reduce the alkalinity of the oceans? I do not know if it was discussed at Sc.S. this paper: Meta-analysis reveals negative yet variable effects of ocean acidification on marine organisms, Kroeker et al., 2010. But it is worth recalling some of the conclusions of this paper: “A variety of biological responses to ocean acidification have been measured across a range of taxa, but this information exists as case studies and has not been synthesized into meaningful comparisons amongst response variables and functional groups.” “Calcification responses varied significantly amongst organisms using different mineral forms of calcium carbonate.” “... the responses of calcifying algae were highly variable.” “Our results support the hypothesis that highly mobile organisms with developed intracellular/extracellular pH regulatory mechanisms may be more resilient to ocean acidification.” “We did not detect significant effects of ocean acidification on photosynthesis in the overall weighted, random effects analysis.” “In conclusion, our analyses revealed a strong negative effect of ocean acidification on marine organisms despite the variation in the sensitivity of taxonomic groups and developmental stages. However, differential sensitivities still have important implications for marine ecosystems where individual species often play disproportionately strong roles in structuring communities ...” ... however wikipedia: “However, some studies have found different response to ocean acidification, with coccolithophore calcification and photosynthesis both increasing under elevated atmospheric pCO2, an equal decline in primary production and calcification in response to elevated CO2 or the direction of the response varying between species. Recent work examining a sediment core from the North Atlantic found that while the species composition of coccolithophorids has remained unchanged for the industrial period 1780 to 2004, the calcification of coccoliths has increased by up to 40% during the same time.” Increasing Costs Due to Ocean Acidification Drives Phytoplankton to Be More Heavily Calcified: Optimal Growth Strategy of Coccolithophores, Irie et al. 2010.: “Contrary to the widely held belief, the evolutionarily optimized population can precipitate larger amounts of CaCO 3 during the bloom in more acidified seawater, depending on parameter values. These findings suggest that ocean acidification may enhance the calcification rates of marine organisms as an adaptive response, possibly accompanied by higher carbon fixation ability. Our theory also provides a compelling explanation for the multispecific fossil time-series record from ~200 years ago to present, in which mean coccolith size has increased along with rising atmospheric CO 2 concentration.” Coral reefs and ocean acidification synopsis ISRS, Briefing Paper 5, 2008.: “Most experiments have not indicated negative impacts on coral tissue growth under elevated carbon dioxide. Indeed, recent experiments have shown that some species cultured under high carbon dioxide concentrations can lose their skeletons altogether without apparent physiological stress or reductions in growth, and then resume skeletal building once carbon dioxide levels are returned to normal.(...).” Impact of CO2-driven ocean acidification on early life-history – what we know and what we need to know, Dupont, Havenhand and Thorndyke, 2009.: “At the same time, more physiological studies are needed to understand contradictory results (e.g. species-specific responses in closely related taxa) and solve apparent paradoxes (e.g. positive impacts in notionally “at risk” species such as calcifying sea urchins). Ultimately, more realistic experiments (e.g. mesocosms, synergy with other environmental parameters, multigeneration, etc.) are needed to upscale experimental data to the ecosystem level. (...)” I also recommend a very interesting discussion by .
    0 0
  28. I also recommend a very interesting discussion by Nature Blogs.
    0 0
  29. Rob Painting...Yes, that was the paper I was talking about. It shows short term effects of acidification on Fe availability due to effects on binding strength of organic ligancs with fe(III). The Sunda article points out the caveats - like whether such a mechanisms will in the long terms increase the total amount of Fe by preventing scavenging of Fe(III) on sinking particles.
    0 0
  30. ATTN Rob The info I have stated in this thread is from Chapter XXI, Carbonic Acid and Its Ions, pp 386-398 _in_ "Principles of Chemistry" by J.H. Hildebrand and R.E. Powell (Sixth Edition, 1962). And the info is straight from the text. So you guys stop bugging me!
    0 0
  31. Sphaerica at 23:06 PM on 31 March, 2011 says: The experiment was well designed and meaningful In these experiments two variables change: the pH and the concentration of CO2 in the water. Does the high conc. of CO2 affect the respiration of the larva and consequently their growth and development? Or Does the lower pH of then medium affect their growth and development? They added 3 antibiotics to the medium to supress growth of microbes. How does pH affect the action of these antibiotics? At the lower pH will the antibiotics influence the growth and development of the larva? I don' know so I'll have to check this out.
    0 0
  32. Hpierce, I do not have a copy of your old chemistry textbook. My chemistry textbook (which was published in 2003), does not give the solubility or ionization of carbonic acid in sea water, only fresh water. I pointed out to you previously that sea water is different from fresh water. In the ocean carbonic acid is primarily ionized, as we have all pointed out to you. If you do not understand the chemistry you should not lecture others who do.
    0 0
  33. h pierce,
    Does the high conc. of CO2 affect the respiration of the larva and consequently their growth and development?
    Does it matter? The study raised CO2 levels, just as is happening in the environment. Your question casts doubt on an irrelevant issue.
    How does pH affect the action of these antibiotics? At the lower pH will the antibiotics influence the growth and development of the larva?
    Now you're clearly just fishing for reasons to distrust the study. Why not just come out and say that it arrived at a conclusion you don't like, cover your eyes, and keep singing until it goes away?
    I don' know so I'll have to check this out.
    Sounds like concern-troll-speak to me. Denial cloaked in faux-reasonable-wary-interest is still denial.
    0 0
  34. H Pierce - "So you guys stop bugging me!" Stick to the facts, and we won't have to correct you. Deal?.
    0 0

You need to be logged in to post a comment. Login via the left margin or if you're new, register here.



The Consensus Project Website

THE ESCALATOR

(free to republish)


© Copyright 2020 John Cook
Home | Links | Translations | About Us | Privacy | Contact Us