Talk:Ocean acidification

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[edit] References

If there's someone who is willing to assist in doing the coding format (not my forte) for the references section, I'll put in some time to citing the material as appropriate. Thanks. Arjuna 00:38, 11 August 2006 (UTC)

[edit] Percent Calculation

The figure has been quoted often about the oceans having increased their acidity by 30% Could a short clarification and calculation be added into this article? Does this refer to negative the base-10 log of the concentrations?

If so, I'm clearly using the wrong number or wrong calculation in the following:

Ratio of underlying concentrations would be,

(10^(-8.104)) / (10^(-8.179)) = 10^ = 10^(0.075) = 1.1885 or so, making present day concentrations (just under) 19% higher. Could someone clarify how the "30% higher" is obtained, and, include a section highlighting this oft-quoted figure, in the article?

(I'm starting to think my calculation is correct and the problem is merely that the numbers in the wikipedia article as only as of 1994...if so, more recent numbers really should be used....if not, then again by all means, please post a corrected calculation. Either way, thanks in advance)

Added later: I've found a reference with the answer to my own question: sure enough, unfortunately, the wikipedia entry is quite out of date with the -0.075 figure from 1994; recent number are about -0.11 for the pH change, see http://www.sciencenews.org/articles/20080315/bob10.asp --Harel (talk) 00:52, 16 March 2008 (UTC)

[edit] Factors which may mitigate ocean acidification

Projections of ocean acidification are based on the expected buildup of carbon dioxide. However, changing weather patterns could prevent parts of the ocean from becoming more acidic.

Well, we have more than just projections, we've already acidified the ocean to a small degree. As for the projections, the largest uncertainty by some margin is what we are going to do. Scenarios of future CO2 emissions by necessity rely on a limited understanding of human and economic factors. Regarding weather, the biggest change that will affect acidification is ocean warming itself (already observed). As well as reducing the amount of CO2 surface waters can hold, warming will tend to stratify the ocean vertically, reducing the quantity of anthro CO2 that makes it to the deep ocean. While this decreases (temporarily) the acidification of the deep ocean, it increases climate change in the meantime. --Plumbago 12:11, 15 September 2006 (UTC)

>>>>>>>>>>>>> We've got to stop this sloppiness in the terminology. Its NOT ocean acidification. Its the reduction in the alkalinity of the oceans. The thing is if people could "THINK" it wouldn't matter if we used these colloquially sloppy definitions. But people can't think and so definitions are important. This concept is clearly a gyp driven only by this sloppy and misleading terminology. No-one could get excited about a tiny move towards neutrality and non-corrosiveness.

"pH is a measure of the acidity or alkalinity of a solution.

Aqueous solutions at 25 ℃ with a pH less than seven are considered acidic, while those with a pH greater than seven are considered basic (alkaline).

The pH of 7.00 is considered neutral at 25 ℃ because at this pH the concentration of H3O+ approximately equals the concentration of OH− in pure water.”

So sayeth wiki. And we never ought deviate from this clear understanding.

Now it wouldn’t MATTER that we deviated colloquollially. ACIDIFICATION is a word that comes ‘trippingly off the tongue” whereas ALKALINITY might get some tongue-tied.

It wouldn’t matter. But as we have seen there are some people who simply cannot think.

And so if once allowed to call things what they wish then they can play any number of word-games.

Acids below 7. Alkalines or Bases above 7.

Going from 9 to 8 is reducing the alkalinity.

Going from 5 to 4 is increasing the acidity.

Get rid of the sloppy and misleading terminology and you won’t make fools of yourselves getting worried over nothing. This is a war against irrationality and keeping your concepts clear is like keeping your powder dry. But anyhow:

“Between 1751 and 1994 surface ocean pH is estimated to have decreased from approximately 8.179 to 8.104 (a change of -0.075)[1][2].”

Gyp or no gyp?

Particularly as we know that some fresh water has been added during that time.


>>>>>>>>>>>>>>>>>>>>>>>>>>>

 —The preceding unsigned comment was added by 122.148.183.191 (talk) 00:14, August 20, 2007 (UTC)
Please read (and, one would hope, understand) the prior discussion on this talk page before ranting. Arjuna 05:05, 20 August 2007 (UTC)

Some of the world's arid areas may see more precipitation (as is already happening in parts of Australia). This has the potential to reverse acidification of seawater by flushing sodium carbonate (a common substance in desert soils) into the ocean. Another possibility is that man may leach carbonate-rich soils to make them productive for agriculture -- again, much of the carbonate would enter the sea.

I don't believe the quantities involved can offset the scale of the CO2 perturbation. It's not strictly my field, but I've yet to see any acidification study that bothers to include minor second-order effects such as this. In the extreme long term (1000+ years) processes such as this will mop up some of the remaining anthro CO2, but they're too minor to much offset what we're doing with CO2. If you think about it for a moment, atmospheric pCO2 rose for ~2 centuries with very modest emissions and normal rainfall. Now our emissions are massive (let alone future emissions ...), so even doubled rainfall is unlikely to much affect these balancing processes. Admittedly, you're arguing that currently dry areas will become wet, so my doubling is likely an underestimate, but even so I think scale is the problem here. Yes, this may well happen, but magnitude is what matters, and I'm not convinced this will play a significant role. However, it's not my field, so I may be convinced with appropriate sources. --Plumbago 12:11, 15 September 2006 (UTC)

Carbonatite volcanism is another potential source of soluble carbonate. Carbonatites are igneous carbonate rocks which are scattered across continents. One active source of carbonatite is known -- the Ol Doinyo Lengai volcano in Tanzania. If others erupt under seawater, their soluble carbonates will raise the pH of waters around them. Tony 09:55, 15 September 2006 (UTC)

Again, scale matters - this is a minor process at best. Furthermore, as this sort of vulcanism has been going on all the time, pre-industrial atmospheric CO2 (which remained broadly constant since the end of the last ice-age) was presumably in balance with it. So it can't play an important role in the ongoing anthro perturbation (i.e. because it's already accounted for in the natural balance). It'd take new vulcanism to change things, and there's no reason to expect that to happen - we may be a new geological force on the Earth, but even we can't cause vulcanism. Anyway, good points raised, but I doubt they're major processes. Cheers, --Plumbago 12:11, 15 September 2006 (UTC)

[edit] Graphs

Graphs. We need graphs dammit. Something like this: http://en.wikipedia.org/wiki/Image:Instrumental_Temperature_Record.png

Something that I can wheatpaste everywhere.

Graphs, dammit! —The preceding unsigned comment was added by 75.73.155.34 (talk) 06:29, 17 December 2006 (UTC).

This preceeding comment was added by ME because I was too lazy to log in--Crucible Guardian 06:31, 17 December 2006 (UTC)

[edit] Acidification

An unknown user added the following to the introductory paragraph: "Since a pH of 7 is neutral, below 7 indicates acidity and above 7 indicates alkilinity, the above-mentioned reduction is actually properly defined as reduced alkilinity rather than increased acidity." I reverted these edits, since (in addition to misspellings) it is factually incorrect. One measure of acidity is the concentration of hydrogen ions, and the documented pH reduction in ocean surface waters represents a 30% increase in hydrogen ions. Thus, it is "acidification", even if it is true that the current ocean surface pH still measures on the alkaline side of the scale. Furthermore, as researcher Ken Caldera has noted, if a cup of hot tea left on a table is "cooling down", not "becoming less hot". Arjuna 23:43, 3 January 2007 (UTC)

Arjuna: I am the unknown user and I acknowledge the typos but the addition was not factually incorrect at all, in fact it reflects standard high-school terminology. I think a short description of the pH scale is important to those unfamiliar with the term. I myself was alarmed at the 'increased acidification' until reading that the pH is still above 8. The tea analogy is not appropriate as one could easily say more neutral rather than more acidic. I added a compromise position based on your own words.
JG17 14:54, 4 January 2007 (UTC)JG17
Sorry, changed it again. I don't think it's the most pertinent place to add this comment about ocean pH. I've moved it lower down in the article, and edited it somewhat (quite a lot actually). The most important part of ocean acidification is not what ocean pH is, but what is happening to it. By prominently mentioning that ocean pH is greater than neutral, I think the previous edit might confuse readers into thinking that just because seawater's on the right side of acid, everything's OK. Furthermore, a discussion of the pH scale is only a single click away, so readers don't necessarily need to be led by the hand. Cheers, --Plumbago 13:28, 4 January 2007 (UTC)

Plumbago: I accept your changes but perhaps not so much the sentiments behind it. I thought well-presented facts were more important than opinions here: This is an encyclopedia, not a propaganda pamphlet and it's best value is in it's neutrality. By one analogy, if you read Franco's revision of Spanish history you will discover that, far from decimating indiginous populations in the bloodthirsty pursuit of gold, the conquistadors apparently brought civilisation, education and much-needed religion to the savages. JG17 14:52, 15 January 2007 (UTC) 4-1-2007 —The preceding unsigned comment was added by User:90.20.203.67 (talk • contribs).

Erm, sorry, I don't follow. The change I made was entirely factual and neutral. I moved the statement about what the ocean's pH is into the main body of the article as it's unnecessary for the opening paragraph. The actual pH value of the ocean is, more or less, secondary in the article to hand. What's significant is that it's changing (hence the article on acidification as a process). My concern was that this significance would be lost to a non-specialist reader were the pH of seawater to be arbitrarily compared to freshwater. Whether seawater is acid or alkaline has little bearing on acidification; adding CO2 to it will acidify it. And I don't quite see what Franco has to do with carbonate chemistry I'm afraid. Cheers, --Plumbago 14:58, 4 January 2007 (UTC)

Plumbago: I did say I accepted the change. It was just your stated concern (here) on what readers may think that I discussed. I had exactly the same concern, but I agree the final statement is perfectly neutral. The Franco reference was about the preference of policy to facts but I admit it was over the top. Mind you, I don't know what cooling tea has to do with chemistry either. Nice talking to you. JG17 14:52, 15 January 2007 (UTC)JG17 JG 4 January 2007

Thanks Plumbago, I think your edits (and comments) got it spot on. As I explained, one measure of acidity (there are many) is the concentration of hydrogen ions, which is precisely what is happening, and so use of the term is perfectly accurate in a university, research, or indeed even a high school setting. So JG's first addition about what was a proper definition was inaccurate. His comments about "propaganda" or Franco don't quite follow either. If he was alarmed about this issue until he found out that seawater is still above 7 pH, "but not afterwards", then I respectfully suggest that his appreciation of the issue would benefit greatly from reading any of the several excellent reports listed in the "further readings" section. Finally, there is a very good discussion about this (definitional) issue at http://www.realclimate.org/index.php?p=169, and which supports the terms used in the article here. Aloha. Arjuna 19:33, 4 January 2007 (UTC)

Arjuna: I did not say that the other definition is inaccurate. I consider only that the article was previously misleading in that some may understand that the sea is acidic but the sea is actually still alkaline by the standard definition of the pH scale which we all learnt in high school. The entire article reads as if it we were dealing with an 'acid sea' rather invoking the 'acid rain' problem. I do appreciate the concerns about reduced pH though I'd respectfully suggest to you that there are far more urgent environmental concerns about the health of the sea resulting from massive pollution. JG17 14:51, 15 January 2007 (UTC)

JG, since the article clearly states that the issue is the change in pH and level of acidity (again, measured by the concentration of hydrogen ions), rather than whether ocean pH is still above 7.0, it's unclear exactly who would feel misled other than someone who hasn't a basic grasp of chemistry. I encourage you to read the scientific papers and articles cited before belaboring this point any further. Thanks for your opinion as to whether there are far more urgent environmental concerns than OA. You are certainly entitled to hold it -- and will be in good company, being consistent with the Bush Administration's current position on the status of CO2 as a non-pollutant, which as you know is the subject of no small amount of debate at present: http://en.wikipedia.org/wiki/Pollution. There is still much scientific uncertainty as to how organisms and ecosystems will respond or adapt to the increased acidity/pH change, and this is in fact something OA researchers are targeting for the next stage of research. However, the prima fascie evidence is not encouraging. Arjuna 22:10, 15 January 2007 (UTC)

[edit] Past and present pH level

The article refers to Jacobson 2005, who estimates pH level for 1751 to be 8.25, while present-day level is supposed to be 8.14. However, NSF, NOAA und USGS (2006): Impacts of Ocean Acidification on Coral Reefs and Other Marine Calcifiers: A Guide for Future Research (PDF, 9,9 MB), p. 4, gives different numbers. There preindustrial pH is supposed to have been 8.16, while today's level is 8.05. Both figures show a decrease of 0.11 points - but which one is correct?? Hardern 15:23, 12 April 2007 (UTC)

Hi Hardern. Good question. I think it probably has to do with the different definitions people use of pH. It's not something I'm an expert on (not least because I don't want to know any more about carbonate chemistry!), but as I understand it, there are (at least) three different pH scales in use today. The free scale (sometimes denoted pHF), the total scale (sometimes denoted pHT) and the seawater scale (sometimes denoted pHSWS). Having just consulted a textbook on the subject (Zeebe & Wolf-Gladrow, 2001, CO2 in seawater: equilibrium, kinetics, isotopes, Elsevier, Amsterdam, Netherlands) it transpires that these are ~0.1 units apart (with pHF being ~0.1 units greater than pHT and pHSWS). I guess that Jacobson (2005) is using the free scale while your NSF document is using the seawater scale (at least, that's what Figure 1-1's caption implies; though it uses the pHT notation). However, I say this with only a very limited grasp of carbonate chemistry (just enough for me to get by on), so please feel free to consult wider. It's certainly annoying that pH turns out not to be as simple as the definition in its article suggests! Anyway, hope this helps. Cheers, --Plumbago 15:56, 12 April 2007 (UTC)
Yes, it helps. Thanks for yout investigation. Do you have any recommendation to which one of the three scales should be used in the case of ocean acidification? Hardern 20:32, 12 April 2007 (UTC)
Erm, no. As I understand it, all three scales are still used by scientists (each has advantages and disadvantages). Consulting my textbook again, they differ in how they handle (or calculate) the importance of ionic species such as sulphate and fluoride. The textbook gives equations to convert between them, but they're not simple to use here. My suggestion would be that we (probably me) expand the pH article to describe the different scales (or at least mention that they exist), and then make sure that articles such as ocean acidification are explicit in stating which scales are used whenever pH values are cited. As I've said already, while I do use pH in my own work (which deals with carbonate chemistry), I'm trying to know only the bare minimum about it, so this won't happen overnight!  ;-) Cheers, --Plumbago 08:30, 13 April 2007 (UTC)
I left them a note. Hardern 12:01, 13 April 2007 (UTC)
For me as a chemist it is very amusing to read that there ought to be more than one pH value, since the pH is defined based on the the concentration of H+ in a solution - and there is just one species of H+ in aqueous solutions. H+ can not remember from which kind of acid or base it is coming from, nor does it behave different then. Could you please provide some more detail information about the definition of the "other" pH values? From a chemical point of view it makes no sense to define and use different definition of the pH value than the international standard one. -- ghw 06:12, 14 April 2007 (UTC)
As a non-chemist, my understanding is that the different pH scales in use in oceanography have methodological roots. It being the weekend, I don't have my textbook to hand, but I think the simple definition (called pHhighschool in Zeebe & Wolf-Gladrow, 2001) comes unstuck in seawater with its multitude of ionic species. To work out the concentration of H+, these other ions need to be accounted for, and that's apparently where the fun begins. Anyway, as there's a little bit more interest now, I'll try to add something about this next week. Maybe put it here first before altering the pH article? I'd be very grateful if you could check over whatever I write since, as I keep banging on, I'm no chemist. Cheers, --Plumbago 06:37, 14 April 2007 (UTC)
ghw, it has to do with the ionic strength and composition of the reference buffer solutions. Page 540 of the article you linked to mentions the existence of special pH scales for blood and seawater. --Itub 16:22, 17 April 2007 (UTC)
An excellent reference... [1] Piyrwq 00:40, 16 April 2007 (UTC)
Good shout. A bit terse however. I've now had a bit of a read of reference 3 below, and have summarised its presentation of the different pH scales as ...

[edit] Seawater

In chemical oceanography pH measurement is complicated by the chemical properties of seawater, and several distinct pH scales exist[1].

As part of its operational definition of the pH scale, the IUPAC define a series of buffer solutions across a range of pH values (often denoted with NBS or NIST designation). These solutions have a relatively low ionic strength (~0.1) compared to that of seawater (~0.7), and consequently are not recommended for use in characterising the pH of seawater (since the ionic strength differences cause changes in electrode potential). To resolve this problem an alternative series of buffers based on artificial seawater was developed[2]. This new series resolves the problem of ionic strength differences between samples and the buffers, and the new pH scale is the referred to as the total scale, often denoted as pHT.

The total scale was defined using a medium containing sulphate ions. These ions experience protonation, H+ + SO42- ⇌ HSO4-, such that the total scale includes the effect of both protons ("free" hydrogen ions) and hydrogen sulphate ions:

[H+]T = [H+]F + [HSO4-]

An alternative scale, the free scale, often denoted pHF, omits this consideration and focuses solely on [H+]F, in principle making it a simpler representation of hydrogen ion concentration. Analytically, only [H+]T can be determined[3], so [H+]F must be estimated using the [SO42-] and the stability constant of HSO4-, KS*:

[H+]F = [H+]T - [HSO4-] = [H+]T ( 1 + [SO42-] / KS* )-1

However, it is difficult to estimate KS* in seawater, limiting the utility of the otherwise more straightforward free scale.

Another scale, known as the seawater scale, often denoted pHSWS, takes account of a further protonation relationship between hydrogen ions and fluoride ions, H+ + F- ⇌ HF. Adding this subtlety changes the concentration of H+T to:

[H+]T = [H+]F + [HSO4-] + [HF]

However, the advantage of considering this additional complexity is dependent upon the abundance of fluoride in the medium. In seawater, for instance, sulphate ions occur at much greater concentrations (> 400 times) than those of flouride. Consequently, for most practical purposes, the difference between the total and seawater scales is very small.

The following three equations summarise the three scales of pH:

pHF = - log [H+]F
pHT = - log ( [H+]F + [HSO4-] ) = - log [H+]T
pHSWS = - log ( [H+]F + [HSO4-] + [HF] ) = - log [H+]SWS

In practical terms, the three seawater pH scales differ in their values by up to 0.12 pH units[1], differences that are much larger that the accuracy of pH measurements typically required (particularly in relation to the ocean's carbonate system). Since it omits consideration of sulphate and fluoride ions, the free scale is significantly different from both the total and seawater scales. Because of the relative unimportance of the fluoride ion, the total and seawater scales differ only very slightly.

  1. ^ a b Zeebe, R. E. and Wolf-Gladrow, D. (2001) CO2 in seawater: equilibrium, kinetics, isotopes, Elsevier Science B.V., Amsterdam, Netherlands (ISBN 0 444 50946 1).
  2. ^ Hansson, I. (1973) A new set of pH-scales and standard buffers for seawater. Deep Sea Research, 20: 479-491.
  3. ^ Dickson, A. G. (1984) pH scales and proton-tranfer reactions in saline media such as sea water. Geochim. Cosmochim. Acta, 48: 2299-2308.
Anyway, how's this look? I'd be very grateful for comments, especially from chemists. I'm suggesting we add this to the article on pH, but make sure that this article's pH values are correctly identified with respect to the scale they're using. Cheers, --Plumbago 13:25, 17 April 2007 (UTC)
It looks pretty good. I made one small change to the text above and renamed sulfate to hydrogen sulfate. One minor style issue is that LaTeX is generally frowned upon in chemistry articles for representing simple inline formulas like HSO4−, because they tend to turn into images that don't match the text well. Finally, one thing that would be good to add is what are the typical differences between the scales in practice. One reference I saw, but which I can't seem to find again, gave numbers like "the pH value in the ____ scale is usually higher than in the ____ scale by about 0.08 pH units". This will help put things into perspective; it explains why many (most?) chemists who, unlike oceanographers, only care about pH with a precision of 0.1 pH units (or even 1.0 pH unit!), are surprised to hear that there is more than one pH scale. --Itub 08:51, 18 April 2007 (UTC)
Added two minutes later: the differences I mentioned were in the link given by Piyrwq: [2] --Itub 08:54, 18 April 2007 (UTC)
Hi Itub. Thanks for reading my text! On the LaTeX point, I did originally write the terms in the way you've now edited them. But I changed them as they then looked odd and not obviously related the same terms in the full equations. It may be frowned upon (and I completely understand why), but to me it makes the text less comprehensible when the appearance of terms changes. But I'm OK about conceding this point.
As regards the difference in the scales, you're absolutely correct - I should have put something in about that. I'll do this later. Reference 1 above (formerly 3; I repositioned it) quotes a slightly different figure (possibly a max. difference) and discusses it a bit. I'll get onto this today. Anyway, thanks again for taking the time to look through my text. Cheers, --Plumbago 09:03, 18 April 2007 (UTC)
Just made a couple of further edits to enumerate the difference in values between the scales. I hope that clears things up. I've also "roman-ised" the font of the equations, etc. I'd only done that in places before, but had meant to do it everywhere. Cheers, --Plumbago 12:35, 18 April 2007 (UTC)
OK. I've rewritten the equations and terms above so that they're all non-LaTeX. I think this solves the style issue nicely. YMMV. Cheers, --Plumbago 08:09, 19 April 2007 (UTC)
It looks perfect to me, go ahead. :) --Itub 08:26, 19 April 2007 (UTC)
Done and dusted. I've also put a note on the talk page there. We should probably move future discussion there from now on. Thanks again Itub for taking the time to read my text. As an aside, it's actually been useful to me to have to go through my textbook and work out the seawater pH story. Cheers, --Plumbago 08:56, 19 April 2007 (UTC)
Great job, thanks! That's somehow the problem I wanted to point at: within "stong solutions" the pH is not direct comparable to that what we learn about pH in school. And the next important thing is: a different pH scale is not direct comparable to the standard pH scale, because they differ non-linear "up to" a certain value. -- ghw 12:37, 20 April 2007 (UTC)

[edit] Poor article

It's a bit poor article, a huge talke here about the meaning of pH Doesn't improve the article.

The article sohuld be more structured, and primairly focus on the risk of this. Because that's what people are trying to warn others of when talking about this. This is not verry wel reflected in the article. It's not about a dispute about pH there is a [wiki link for that topic] should be offtopic here.

When algea can no longer survive as a result of acidification, we get dead zones in the sea Those where allready in the news last year. The sea can realy starve without oxygen, well that is some species anaerobic bacteria can service it, they produce [[ http://www.ilo.org/public/english/protection/safework/cis/products/icsc/dtasht/_icsc01/icsc0165.htm hydrogensulfate]] This happened the last time when earth's seas died (during perm), as a not so small side effect about 90% of land based live also died in that period. It's about going to happen again soon. One of the greatest mass extinctions in Earth's history occurred at the end of the Cretaceous era, sixty-five million years ago and is believed to be caused by sea acidification

Note this topic is also closely related to melting polar icecaps, known to be the engine of sea water transport trough various oceans, this water system transports the oxygen troughout the ocean. It's that which is required to keep marine life a live.

82.217.143.153 (talk) 23:06, 11 March 2008 (UTC)

Sorry, but I'm afraid I'm going to disagree (though, given I wrote most of the article, that's probably not a surprise). Firstly, the content of the talk page (your complaint about the pH discussion) is neither here nor there - talk pages serve to discuss improvements, and in this case the improvement discussed here was actually made to the pH article in the end. Secondly, the article discusses the known risks of acidification, which primarily boil down to disruption to calcifier communities (corals, coccolithophorids, pterpods, etc.). Ocean dead zones are not directly connected to acidification at all - as the article on the subject describes, they are related to depletion of dissolved oxygen. Nor is acidification directly connected to the loss of polar ice caps - these are separate problems [*]. Anyway, I hope this clears up some of the difficulties that you have with this article, but if you have any others, please just raise them here. Cheers, --Plumbago (talk) 08:43, 9 April 2008 (UTC)
[*] Though there is an interesting connection. Climate change (which causes polar icecap loss) is primarily a consequence of CO2 in the atmosphere, while acidification is a consequence of CO2 in the ocean. An increase in one problem is offset by a decrease in the other problem. As time passes the balance of the two problems is gradually shifting from climate change to ocean acidification as CO2 is absorbed by the ocean.

[edit] Coccolithophore rewrite

Hi, I've been keeping half an eye on your re-write and have to say, you've done an incredibly good job. If anything, perhaps the bias has gone a bit further to the "bad news" side than I'd like - but then I guess that's mainly because the "good news" scenario is more appealing to my optimistic tendencies! My one comment would be that the last two sections of the paragraph are still written as if the "bad news scenario" was true - it perhaps needs to be clearer that the decreased CO2 burial is due to shoaling of the lysocline (if that is what the paragraph's referring to), because the coccolith weight-gain data seems to suggest the opposite. Further, the paragraph

There is also a suggestion that the effect of acidification on coccolithophores may have secondary effects on climate change, by decreasing the earth's albedo via their effects on oceanic cloud cover

doesn't make it clear which effect it's referring to - if abundance has risen, as per the science report, the sense of the sentence needs inverting.

Hope that's helpful, and thanks again for your great work on the article! Verisimilus T 11:08, 24 April 2008 (UTC)