The world’s marine ecosystems risk being severely damaged by ocean acidification unless there are dramatic cuts in CO2 emissions, warn scientists.
The researchers warn that ocean acidification, which they refer to as “the other CO2 problem”, could make most regions of the ocean inhospitable to coral reefs by 2050, if atmospheric CO2 levels continue to increase.
This does indeed sound alarming, until you consider that corals became common in the oceans during the Ordovician Era – nearly 500 million years ago – when atmospheric CO2 levels were about 10X greater than they are today. (One might also note in the graph below that there was an ice age during the late Ordovician and early Silurian with CO2 levels 10X higher than current levels, and the correlation between CO2 and temperature is essentially nil throughout the Phanerozoic.)
Perhaps corals are not so tough as they used to be? In 1954, the US detonated the world’s largest nuclear weapon at Bikini Island in the South Pacific. The bomb was equivalent to 30 billion pounds of TNT, vapourised three islands, and raised water temperatures to 55,000 degrees. Yet half a century of rising CO2 later, the corals at Bikini are thriving. Another drop in pH of 0.075 will likely have less impact on the corals than a thermonuclear blast. The corals might even survive a rise in ocean temperatures of half a degree, since they flourished at times when the earth’s temperature was 10C higher than the present.
Chris J (17:42:44) :
“I don’t understand your claim that there’s no indication that the ‘calculated’ dataset was produced with CTD, nutrient, DIC, and TA data. It says ‘calculated’ right on the graphic.”
Such a long post to basically say “nuh uh” and “I’m certain about this”.
I’ve reproduced the below a few times, yet you don’t understand why I am questioning the “calculated” data?
http://hahana.soest.hawaii.edu/hot/protocols/chap23.html
“pH is measured electrochemically using a combination
electrode.”
“The pH of seawater samples is calculated using the
electrode slope and isoelectric point and sample temperature.”
You are claiming the ph trend graph does not represent either of these methods, right?
Chris,
I have been trying to figure out what is confusing you, and think I am getting a grasp on it. It seems to derive from this equation, which has apparently lead you to the belief that that limestone formation releases CO2 (even though it obviously sequesters it.)
Ca++ + 2HCO3- -> CaCO3 + CO2 + H2O
Hopefully this explanation will help.
Start out with two CO2 molecules and make two carbonic acid molecules
2CO2 + 2H2O -> 2H2CO3
The two carbonic acid molecules decompose to two bicarbonate ions
2H2CO3 -> 2HCO3- + 2H+
And those two bicarbonate ions form one CaCO3 molecule and one CO2 molecule when combined with a calcium ion.
Ca++ + 2HCO3- -> CaCO3 + CO2 + H2O
So we started out with two CO2 molecules, and ended up with one. In other words, half of the CO2 we started with was sequestered in limestone.
Remember that cement manufacture releases huge amounts of sequestered CO2, when the limestone is heated.
Steven,
And on that note, lets remember that there is a pH buffering
system that limits seawater pH, many say to between 7.5 and 8.4.
That should enforce the idea that there can be no “acidification” process.
If the crater can’t be found then other supporting evidence needs to be produced. Has it?
Abstract
PJ Mayhew et al. (2007) A long-term association between global temperature and biodiversity,
Our findings may have implications for extinction and biodiversity change under future climate warming.
We can dismiss this paper as It’s conjecture built on a preconceived notion.
Keller G (2005) Impacts, volcanism and mass extinction: random coincidence or cause and effect? Austral. J. Earth Sci 52 725-757.
(I’ve reproduced the abstract below [***] )”
Sorry but I need the full paper to study before I can research their findings.
Wignall P (2005) The link between large igneous province eruptions and mass extinctions Elements 1, 293-297
Abstract: “In the past 300 million years, there has been a near-perfect association between extinction events and the eruption etc
This is smoke and mirrors, throughout earths history there have been large
tectonic and geothermal events. You will always find them somewhere near extinctions and not so near.
I do not do science through abstracts. I need to study the full paper. All to often I see this tactic used by AGW proponents. Abstracts are only a preface to the work. They are not intended to be used as factual a representation of any scientific certainty in any field.
Current understanding is that the Chicxulub impact is the best candidate so far. In order for that not to be the case then compelling evidence needs to be produced to the contrary. That means field research, not theory.
Wignall Et al State.
The best links between extinction and eruption are seen in the interval from 300 to 150 Ma.
So these researchers are dealing with extinctions as a job lot. Yes very scientific. And this.
such as release of methane from gas hydrate reservoirs or shut-down of photosynthesis in the oceans, are probably required to achieve severe green-house warming.
Shutting down photosynthesis would lead to a massive decay in vegetation and that would lead to methane and CO2 levels to rise at a precipitous level.
Present day evidence shows volcanic action leads to cooling and the blocking of solar radiance. It also shows that warming leads to elevated CO2 and Methane levels. Not the other way round.
My last message was for.
foinavon (05:17:36) :
JamesG (10:09:37) :
Mary Hinge
“Your comment shows what is wrong with the sceptic view. You just don’t read the evidence,or ignore it if you do. ”
I’m not ashamed of being skeptical. With a lack of real evidence, the alternative to being skeptical is often to jump to the wrong conclusion.
Your own comments meanwhile show the two main problems with the AGW view:
a) You accept mere opinion as “evidence”. It never is! In a court it would be called “hearsay”. In science it is called “theory”. All opinions ultimately need some sort of backup data.
James:
In science, a “theory” is the highest level of understanding, backed by much hard data. This might include: “the theory of gravity”, the “theory of evolution”, “the atomic theory of matter”, the “germ” theory of infectious disease, etc. The use of the word “theory” by scientists is very different from the everyday use in popular culture. In most cases, what you talk about as “scientific theory” is backed up by hundreds or thousands of data-filled scientific reports.
You need a research library or subscriptions to access much of this literature, although more and more is available on line. A good starting point would be to read a text book to get an overview, before reading more technical data-filled articles. Just because you haven’t done a literature search does not mean that the scientific evidence (including much quantitative data) does not exist. What you dismiss as conjecture is often based on great volumes of data that you have missed or ignored.
Here is a summary which hopefully end all of the ridiculous claims that have been made on this thread.
Limestone formation – sequesters CO2 and increases the amount of H+ (i.e. increases acidity)
2CO2 + 2H2O -> 2H2CO3
2H2CO3 -> 2HCO3- + 2H+
Ca++ + 2HCO3- -> CaCO3 + CO2 + H2O
Limestone dissolution – releases CO2 and reduces the amount of H+ (i.e decreases acidity)
CaCO3 + CO2 + H2O -> Ca++ + 2HCO3-
2HCO3- + 2H+ -> 2H2CO3
2H2CO3 -> 2CO2 + 2H2O
This shows how the ocean pH is buffered. As acidity increases, limestone dissolves, releasing CO2, removing H++, and increasing pH.
I tried this out in a beaker last night. I put some pure optical calcite (CaCO3) in vinegar. It released lots of CO2 bubbles, until enough of the H+ was removed to bring the pH up to a point where the dissolution stopped. (More CO2, higher pH.) This is why it is extremely difficult to lower the ocean pH, and why you can’t make the oceans chemically absorb a lot more CO2. There are billions of tons of CaCO3 in the ocean which buffer the system.
Bill D
You just demonstrated another trait common to AGW theorists, viz:
3) Ignore the substantive argument in order to pick on a single word or phrase and pedantically debate it’s meaning.
Yes, while some theories are indeed backed up by data, many more are not. And this particular one – that the coral die-off is largely due to CO2 – has no real foundation. In place of data we have biased opinion and illogical thought processes.
Ok, coral exists in a narrow temperature range, so of course it’s perfectly valid to say that higher temperatures will kill some coral. Yes you can show that in experiments. But that is only half of an argument. The remaining half is that other areas that were previously too cold should now produce more coral, as indeed the scientists I referred to in the Nat Geo reference above have clearly said. All things being equal, warmer seas should therefore produce slightly more coral, not less. Any die-off from a tiny rise in tropical sea temperatures, which as it happens, stopped 5 years ago according to the latest, most-advanced instruments, just does not explain the coral die-off.
Conversely, the massive exodus of people to coastal regions in recent years (20% per year in the USA and many parts of Asia) explains it perfectly. Hence also the reason why Cuba is relatively unaffected by coral die-off (excepting of course in the 3% of it’s coast which is heavily populated).
None of this is too difficult to work out – and many scientists are saying it too but their voices aren’t heard above the activist din until they say something like “of course global warming is very important too”. I suspect that if you link your research to CO2, and even better if you have a catastrophic prediction, then you extend your chances of getting more funding. This is likely the only real positive feedback loop in the whole charade.
To make it even simpler. Almost all of the carbon sequestered in limestone (CaCO3) started out as CO2 in the atmosphere. There are huge volumes of limestone in the crust of the earth, making up nearly 10% of all sediments. The formation of these limestones has removed massive amounts of CO2 from the atmosphere over time.
These facts should be painfully obvious to anyone calling themselves a scientist. It is well known that cement manufacture returns sequestered carbon to the atmosphere, and there are numerous theories floating around about how subduction of limestones into volcanoes has caused spikes of CO2 in the past.
(Typo in my previous post – should read “H+” not “H++” )
“CaCO3 cannot simultaneously sequester and produce CO2 upon reaction with CO2.”
Misplaced in this presentation is that one balanced equation for a fluence between the atmosphere and the geologic leg of the Carbon Cycle is somehow exhaustive. A mindlessly simplistic notion.
In fact, the weathering of exposed calcite is predominantly, by many orders of magnitude, a return of CO2 to the oceans. Any combination of direct fluences with the atmosphere is a bit player.
Steven Goddard (23:39:15) :
Here is a summary which hopefully end all of the ridiculous claims that have been made on this thread.
No it doesn’t because it is itself a ridiculous claim!
Limestone formation – sequesters CO2 and increases the amount of H+ (i.e. increases acidity)
2CO2 + 2H2O -> 2H2CO3
2H2CO3 -> 2HCO3- + 2H+
Ca++ + 2HCO3- -> CaCO3 + CO2 + H2O
Limestone dissolution – releases CO2 and reduces the amount of H+ (i.e decreases acidity)
CaCO3 + CO2 + H2O -> Ca++ + 2HCO3-
2HCO3- + 2H+ -> 2H2CO3
2H2CO3 -> 2CO2 + 2H2O
This shows how the ocean pH is buffered. As acidity increases, limestone dissolves, releasing CO2, removing H++, and increasing pH.
No it doesn’t because you’re not talking about seawater, any discussion of which has to include alkalinity!
I tried this out in a beaker last night. I put some pure optical calcite (CaCO3) in vinegar. It released lots of CO2 bubbles, until enough of the H+ was removed to bring the pH up to a point where the dissolution stopped. (More CO2, higher pH.) This is why it is extremely difficult to lower the ocean pH, and why you can’t make the oceans chemically absorb a lot more CO2. There are billions of tons of CaCO3 in the ocean which buffer the system.
And when it starts raining acetic acid (pKa ~4.75, pH vinegar ~2.4) we should worry about that! However, since we’re discussing rain with CO2 dissolved in it (pH ~5.6) falling on the ocean your ‘bait and switch’ tactic should be ignored.
‘A little knowledge is a dangerous thing’ and on this subject Steve you only have a little knowledge!
Steven Goddard (09:04:15) :
Simon Evans,
Think about your last post.
The IPCC is claiming a much accelerated rate of acidification over the remainder of the century. How can CO2 absorption be slowing down and accelerating at the same time?
Of course it can’t be, but I think you are making an oversimplified assumption that the rate of acidification is linearly related to the rate of absorption.
The relative proportion of the three forms of DIC (CO2, HCO3/– and CO3/2–) reflects the pH of seawater and maintains it within relatively narrow limits. This
DIC operates as a natural buffer to the addition of hydrogen ions—this is called the ‘carbonate buffer’. If an acid (such as CO2) is added to seawater, the additional hydrogen ions react with carbonate (CO3/2–) ions and convert them to bicarbonate (HCO3/–). This reduces the concentration of hydrogen ions (the acidity) such that the change in pH is much less than would otherwise be expected (Annex 1).
When atmospheric CO2 dissolves in seawater, the oceans increase in acidity but, because of the carbonate buffer, the resultant solution is still slightly alkaline.
The capacity of the buffer to restrict pH changes diminishes as increased amounts of CO2 are absorbed by the oceans. This is because when CO2 dissolves, the chemical processes that take place reduces some carbonate ions, which are required for the ocean pH buffer (Annex 1). (my bold)
http://royalsociety.org/displaypagedoc.asp?id=13314
Secondly, as I have pointed out repeatedly, the existence of La Nina is proof of the rapid interchange of deep and shallow water in the Pacific. Where do you think the cold water came from?
Well the cold water self-evidently didn’t come from somewhere that had previously been instantaneously mixed! Moreover, the deeper water welling up is richer in CO2 (organic matter having decomposed as it sinks), so the effect of that circulation is to decrease the pH of near-surface water. Furthermore, this circulation does not extend to the deep ocean sea bed.
Given that CO2 enters the oceans by exchange across the air–sea interface, it follows that analysis of the distribution of CO2 uptake show highest values (and
therefore the greatest pH change), in near-surface waters. As it takes many centuries for the downward mixing of CO2, little of the CO2 derived from human
activities has yet reached the deep oceans. When averaged for the oceans globally, about 30% of the anthropogenic CO2 is found at depths shallower than
200 m, with 50% at depths less than 400 m, leading to the conclusion that most of the CO2 that has entered the oceans as a result of human activity still resides in
relatively shallow waters. (Ibid.)
You may take the view that complete ocean mixing is effectively instantaneous whilst oceanographers tell us it takes tens of thousands of years. You view has radical implications way beyond ocean acidification, of course, since we would need to completely reconsider all modelling of the oceans. You might like to consider the fact that your view of such rapid mixing implies that the oceans have already ‘warmed through’ far more than has been thought. You can’t have rapid chemical mixing of the entire ocean by means of circulation, as you suggest, without having rapid thermal mixing. So perhaps, Steven, you might ‘think about your last post(s)!
Phil,
It is astonishing to me that you continue this. The entire premise of the BBC claim is that “acidification” of the ocean to a pH of 7.8 or so will lead to dissolution of carbonate shells. You have completely lost track of that and are now arguing that “5.6 pH rainwater” can not dissolve calcite. You are carelessly arguing that the BBC is wrong.
But even worse is your ridiculous claim that rainwater can’t dissolve limestone. Of course it can – that is how limestone caverns form. It will not dissolve calcite as fast as vinegar, but the process is the same. Rainwater dissolves all kinds of rocks. That is how the minerals got in the ocean, and what makes mountains erode to the sea.
BTW – Rainwater is pH 5.2 or lower. Please stop the FUD. You have no idea what you are talking about and are continuing to make a mockery of science.
@ur momisugly Phil. (09:57:57) :
“The absorption of CO2 depends on the Revelle factor of the sea water.”
The absorption of CO2 depends on ocean chemistry that the dimensionless Revelle factor (buffer factor) facilitates calculating in the range under consideration. It’s just an engineering type of shorthand to account for complex processes that one doesn’t want to have to recalculate each time to solve a problem, like the Prandtl number in fluid dynamics.
In any case, please note that Roger Revelle (of the Revelle and Suess, 1957 paper that intrduced the concept of the Revelle factor), Gore’s “mentor,” says that Gore is full of it (not in such colorful language, but in words to the same effect).
http://motls.blogspot.com/2007/04/gores-guru-dr-roger-revelle-disagreed.html
Please read the reference given for what Revelle says, here…
http://www.nationalpost.com/story.html?id=58e0c50c-1631-46ca-8719-778c0973526e
It’s from the series “The Deniers” I referenced in a comment above, and in it he lists some of the benefits that elevated CO2 can have for the planet.
Thanks for bringing that into the discussion.
Steven Goddard (10:05:27) :
Phil,
It is astonishing to me that you continue this. The entire premise of the BBC claim is that “acidification” of the ocean to a pH of 7.8 or so will lead to dissolution of carbonate shells. You have completely lost track of that and are now arguing that “5.6 pH rainwater” can not dissolve calcite. You are carelessly arguing that the BBC is wrong.
But even worse is your ridiculous claim that rainwater can’t dissolve limestone. Of course it can – that is how limestone caverns form. It will not dissolve calcite as fast as vinegar, but the process is the same. Rainwater dissolves all kinds of rocks. That is how the minerals got in the ocean, and what makes mountains erode to the sea.
BTW – Rainwater is pH 5.2 or lower. Please stop the FUD. You have no idea what you are talking about and are continuing to make a mockery of science.
It’s you who is ‘making a mockery of science’ with your ridiculous post comparing the effect of adding vinegar to CaCO3 with adding a CO2 solution to seawater! You don’t know what you’re talking about and you continue to ‘bait and switch’ when cornered. You have zero credibility on this subject. You post your schoolboy science up against PhDs in the subject with the arrogance of a true believer!
“‘A little knowledge is a dangerous thing’ and on this subject Steve you have a little knowledge!”
And you have not attempted to demonstrate this opinion as fact. All I see is bluster, no content reasoning from assumptions to conclusions employing facts in the public view.
Like I said above, my sisters, at UW-Madison were required to pass Organic chemistry for degrees in Interior Design.
I’ve seen no evidence of similar rigor in your background over the past couple of weeks. “Absence of evidence does not guarantee evidence of absence”, but the scales are sickenly tilted.
JamesG (05:49:14) :
Bill D
You just demonstrated another trait common to AGW theorists, viz:
3) Ignore the substantive argument in order to pick on a single word or phrase and pedantically debate it’s meaning.
Yes, while some theories are indeed backed up by data, many more are not. And this particular one – that the coral die-off is largely due to CO2 – has no real foundation. In place of data we have biased opinion and illogical thought processes.
James:–first, I am hardly an AGW theorist, as all of my scientific publications are based on lab and field experimentsl and this research mainly deals with lake food chains, and population studies. My research has a very strong emphasis on collecting data to test hypotheses. I find that you and some others on this blog have the trait of ignoring vast amounts of the scientific literature, most of which is based on experiments and hard data.
Second, the coral literature shows that most of the die-offs have been closely tied to high extreme temperatures. I agree that acidification has only recently become an issue and that it is not the main cause for coral die offs and extinction risks. Thus, I agree that most of the die offs have been due to sea warming, rather than acidification. Scientists who study the effect of warming on corals are concerned about climate, but their research does not depende on the cause of the warming, only that it has occurred and that corals are still at risk. Most scientists are not confident that the warming of the last few decades will suddenly reverse, although it would be great if this were true.
The extent of acidification is relatively easy to predict if we can predict atmopheric CO2. Numerous experiments have already confirmed that corals are harmed by decreases in sea water pH. I also agree that eutrophication and other pollution problems associated with human populations are also harmful to corals. However, when you look at georgraphic patterns coral die offs in the Carribian, Indian and Pacific Oceans, it is easy to see that the pattern is not caused by local human populations. In fact, during the last 20 years when the coral die offs have become more severe, human pollution draining into ocean waters has stabilized or declined.
More speculation by Bill D. “The models predict that XXXXXX” – run for the hills!
Bill D (11:38:31)
“The extent of acidification is relatively easy to predict if we can predict atmopheric CO2. Numerous experiments have already confirmed that corals are harmed by decreases in sea water pH. I also agree that eutrophication and other pollution problems associated with human populations are also harmful to corals. However, when you look at georgraphic patterns coral die offs in the Carribian, Indian and Pacific Oceans, it is easy to see that the pattern is not caused by local human populations. In fact, during the last 20 years when the coral die offs have become more severe, human pollution draining into ocean waters has stabilized or declined.”
Lets look at the science here then.
UV Exposure of Coral Assemblages in
the Florida Keys
Richard G. Zepp
Bleaching, through interactions with other factors such as sedimentation, pollution, and bacterial infection, can contribute to the destruction of large areas of a reef with limited recovery, and it may be induced by a variety of stressors ranging from exposure to unusually warm temperatures, salinity, and solar radiation. Recent research has implicated both the UVR (280 – 400 nm) and PAR (400-700 nm) components of solar radiation in various responses of coral reefs to global change. Changes in solar UV reaching the coral reefs have been caused by human alterations of atmospheric composition such as depletion of the ozone layer. In addition, changes in the composition of the water over the reefs can have important effects on the penetration of UV and visible light to the reef surface. Such changes can be caused by shifts in runoff of UV-absorbing substances from land, clarification of the water under doldrum conditions associated with global warming and changes in organisms that live near coral reefs that produce sunlight-absorbing substances. This report provides a review of past work that has been conducted on light exposure of coral reefs, in particular in the UV region. The report then describes a case study of factors that are affecting UV exposure of the coral reefs in the Florida Keys. The intended audience of this report is coral ecologists, optical oceanographers and managers and EPA environmental scientists and ecologists who must routinely analyze and estimate stressors for ecological or human health exposure assessments.
Abstract
Recent studies have indicated that solar radiation can be a significant stressor of coral assemblages in tropical and subtropical marine environments. Here the scientific literature related to the interactions of solar radiation with coral reefs is reviewed, with emphasis on harmful effects of solar UV radiation (UVR). Results of a case study of corals’ UV exposure in the Florida Keys also are presented in the report. UV exposure was quantified using diffuse attenuation coefficients that were determined using downwelling vertical profiles of UV and visible radiation from sites located at the Upper, Middle and Lower Keys and the Dry Tortugas. For comparison, absorption and fluorescence spectra of the filtered water samples from these sites were measured. Absorption and diffuse attenuation coefficients were highly correlated in the UV-B (290-315 nm) spectral region and ratios of absorption to diffuse attenuation coefficients were > 0.9 throughout this spectral region. Absorption coefficients in the 300 to 500-nm spectral region could be closely described by a nonlinear exponential function. These results indicated that the penetration of solar UV into waters over the coral reefs in the Florida Keys is controlled by the chromophoric component of dissolved organic matter (CDOM) in the water. Analyses of the dependence of underwater UV irradiance on changes in atmospheric ozone or in the UV attenuation coefficients of the water over the reefs indicate that: (1) the dependence on ozone or UV attenuation coefficients can be quantified using radiation amplification factors (RAF); RAFs can be computed using a power relationship for direct UV damage to DNA or for other UV damage to the photosynthetic system of the zooxanthellae associated with corals; (3) UV damage of both types is more sensitive to changes in water UV attenuation coefficients than total ozone, especially damage to the photosynthetic system; (4) RAFs for direct DNA damage to corals caused by changes in ozone are reduced by UV light attenuation in the waters overlying the reefs.
http://www.epa.gov/AthensR/publications/reports/Zepp600R03095UVExposureCoral.pdf
So simply we can assertain that changes in water clarity are the primary mechanism for coral bleaching.
gary gulrud (11:21:06) :
“‘A little knowledge is a dangerous thing’ and on this subject Steve you have a little knowledge!”
And you have not attempted to demonstrate this opinion as fact. All I see is bluster, no content reasoning from assumptions to conclusions employing facts in the public view.
On the contrary it is Steve who continually blustered in the face of evidence and references from Chris J. and me.
Like I said above, my sisters, at UW-Madison were required to pass Organic chemistry for degrees in Interior Design.
I’ve seen no evidence of similar rigor in your background over the past couple of weeks. “Absence of evidence does not guarantee evidence of absence”, but the scales are sickenly tilted.
Only by your bias. In fact a former grad student and former post doc from my lab of mine are now professors at UW-M although your sisters are unlikely to have come across them considering their major.
Phil,
Please tell us how limestone caverns form, if you believe it is not due to rainwater dissolution.
If what you say about your background is true, it is terribly sad that your university keeps a professor who is [snip – no ad homs – Anthony]
Steven Goddard (10:05:27) :
From decades old memory before acid rain became all the rage, I recall that that rainwater was 5.7. Perhaps extra CO2, NOx, and SO2 have brought the pH of typical rain down to 5.2. I’ve heard of acid rain in the pH 3-4 range, so 5.2 would be an easy achievement.
Poking around with Google, I see a lot of 5.6 and 5.7. The closest thing to real science is http://www.treesearch.fs.fed.us/pubs/11066 and it refers to a cooling tower changing local rain pH from 3.4 to 4.6 to a range of 4.0 to 4.8. This was in 1974 at the 710 MW Chalk Point power plant in southern Maryland, prime acid rain dumping ground I would think.
Steven Goddard (16:34:28) :
Phil,
Please tell us how limestone caverns form, if you believe it is not due to rainwater dissolution.
Why, what possible relevance is it to what happens in seawater? Chris J. and I have been trying to explain that to you but you just won’t listen. It’s way more complicated than you attempt to present it, for example a change in seawater composition to pH 8.0, alkalinity 2 mequ/l, salinity 33 0/00, temperature 20ºC, and calcium 10% low from nominal would put aragonite at the verge of dissolution.
When you discussed this reaction:
Ca2+ + 2 HCO3- → CaCO3 + CO2 + H2O
you stated that during CaCO3 precipitation CO2 is liberated. However, in seawater your conclusion that [CO2] in solution is increased by one mole per mole CaCO3 ‘sequestered’ is incorrect. The correct analysis takes into account that of TCO2 and TA decrease in the ratio 1:2 and the buffer capacity of seawater. So the seawater gets more acidic because the decrease in alkalinity outweighs that of total carbon and [CO2] increases. At surface ocean conditions (TCO2=2000 μmol kg-1, pH=8.2, T=15°C, S=35), [CO2] increases by only ~0.03 μmol per μmol CaCO3 precipitated.
Note that you have been abusive to both Chris J. and me.
Ric,
I took the number of 5.2 from Wikipedia Clean or unpolluted rain has a slightly acidic pH of about 5.2
It doesn’t make any difference though if it is 5.2 or 5.5, the level of acidity only affects the rate at which the calcium carbonate dissolves. A good read from the University of Waterloo.
http://www.science.uwaterloo.ca/~cchieh/cact/applychem/waternatural.html
“The solubility increases as the pH decrease (increase acidity). This is compounded when the water is saturated with carbon dioxide, CO2. Saturated CO2 solution contains carbonic acid …. Rainwater is saturated with CO2, and it dissolves limestones. When CO2 is lost due to temperature changes or escaping from water drops, the reverse reaction takes place. The solid formed, however, may be a less stable phase called aragonite, which has the same chemical formula as, but a different crystal structure than that of calcite.”
@ur momisugly Steven Goddard,
Steven, your incapacity to grasp even the basics of carbonate chemistry here is getting very old. You’re wrong again (see below).