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This YouTube video snippet, Dr Don Easterbrook claims there is not enough CO2 available to affect the oceans enough to make them go lower than a pH of 7, and hence there is no acidification.

Is this true or are there other factors that could cause Ocean Acidification?

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This just is about use of language: ocean water is naturally mildly alkaline, and an increase in disolved carbon dioxide makes it very slightly less alkaline. Is this acidification or neutralisation? By contrast, rain water is naturally acidic, and more so as a result of pollutants by sulphur and nitrogen oxides. –  Henry Apr 2 at 13:00
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The definition of acidification given in the OED supports its use in the way that it is used in this context. It is a shame that a government committee wasted its time on a discussion of pedantry, rather than discussion of the effects of the oceans becoming less alkaline or more acidic. –  Dikran Marsupial Apr 2 at 13:25
    
@Dikran Marsupial: That is an overstatement. The definition "Conversion into an acid" is not consistent with your statement. "Making something acidic" is not consistent with your statement. But "Making something more acidic" is consistent with your statement. So this is about use of language, and the OED definitions can be read both ways, reflecting actual usage. –  Henry Apr 2 at 14:03
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Nobody is claiming that the oceans will become acidic (in the sense of a pH less than 7), the word is being used in the sense of "to become more acidic", which is contained in the OED definition. Easterbrook claims that scientists are saying that the oceans will become acidic, but that doesn't mean that it is what they have actually said. See e.g. IPCC AR4 report. –  Dikran Marsupial Apr 2 at 14:07
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@Celeritas the edit you recently proposed unfortunately changed the question quite radically, by adding a new claim about noticeable effects on ocean species, and acidification at a non-negligible rate. Not only was that claim uncited, but it's sort of in the opposite direction to the claim that's already in the question. I've rolled it back for now. If you've got a new question about the rate and impact of acidification, it would help to post it as a new question, with a cited source, so that we've got a very specific claim to investigate. –  EnergyNumbers Apr 3 at 1:02
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As far as I know, nobody is claiming that ocean acidification will result in the pH going lower than 7, so this is at best a straw man. The IPCC project a reduction by 0.3 - 0.4 units by 2100 (e.g. AR4 WG1 report) (current pH is about 8.14). The pH does not need to fall as far as 7 for there to be substantial impacts (see the three sources given for details).

I suspect this is just silly pedantry on the grounds that a pH greater than 7 is alkaline, so it is inaccurate to say that it isn't ocean acidification but ocean dealkalinisation. However this is bogus as pH is getting more acidic and less alkaline as the pH drops, so it is perfectly correct to say that the oceans are becoming more acidic, even if the pH remains higher than 8. It is a bit like defining "hot" as meaning above 0C and "cold" as below 0C and then complaining when someone describes a change from 2C to 1C as "becoming colder" and insisting on it being described as "becoming less warm".

The glossary of the IPCC A4 report defines ocean acidification as "A decrease in the pH of seawater due to the uptake of anthropogenic carbon dioxide", so they make it very clear that they mean only a decrease in pH. Scientific terminology varies from field to field, if you want to understand the science, you do need to understand the terminology used in that field and not to try to impose your own definitions on what they have said.

Having now seen the video, my suspicion was entirely correct. The OED defines "acidification" as "The action or process of making something (more) acidic; conversion into an acid; addition of acid. Cf. acidify v.". The inclusion of "(more)" means that the scientists use of the term is completely in accordance with normal English usage. Senator Ericksen at about 1:03:15 makes a comment that suggests that he understands that "less alkaline" and "more acidic" means essentially the same thing.

BTW, a pH of 8.2 is not "strongly alkaline" as Easterbrook states, that is just hyperbole. If seawater is "strongly alkaline", one wonders how he would describe drain cleaner! ;o)

Having looked at the video again, excluding the pedantry issue, Easterbrook only makes one scientific argument, which happens to be incorrect (which makes it rather ironic he described it as Chemistry 101 ;o). He states "The effect of global warming is to make the oceans more alkaline, not more acidic, because warming drives CO2 out of the oceans". Now it is true that the solubility of CO2 in water decreases with increasing temperature, but that is only part of Henry's law the other part is that the solubility depends on the difference in partial pressure in the atmosphere and the concentration in the water (the constant of proportionality depends on temperature). So increasing temperatures will have the effect of reducing solubility, but the increasing partial pressure of CO2 will have the opposite effect, tending to increase solubility. Which effect is strongest? Well the fact that the oceans are acidifying (rather than becoming more alkaline as Easterbrook predicts) and that atmospheric CO2 levels are rising at only about half the rate of anthropogenic emissions is very strong evidence that the oceans are taking up large amounts of CO2. It is the interplay of these two factors that to a large extent explains why CO2 levels have been so stable for the last million years, the pre-industrial equilibrium is the point where these two influences balance.

There is a good series of articles on Ocean Acidification at SkepticalScience.com, written by Doug Mackie that sets out the basics in some detail.

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Is there room in your answer for some discussion about how it isn't the extra CO2 in the atmosphere that is acidifying (dealkalising?) the oceans, it's the extra CO2 that has already dissolved in the oceans. It feels like he is pointing to a smoking gun and saying "That smoke has very little momentum - a gun could hardy kill someone." I don't have any references to support me here :-( –  Oddthinking Apr 2 at 13:38
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I'm not sure I quite understand the distinction you are making as the additional CO2 that has already dissolved in the oceans was dissolved as a result of increasing atmospheric CO2 (Henry's law) which is in turn due to anthropogenic emissions. Essentially fossil fuel emissions are increasing the carbon circulating through the carbon cycle, some of that is in the atmopshere, some in the oceans and some in the biosphere. As far as I could see Easterbrook had no real scientific evidence about the cause of global ocean acidification and was just trying to focus on the possibility of ... –  Dikran Marsupial Apr 2 at 13:44
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I don't think that is actually the case as there has not been time for the oceans and atmosphere to equilibriate. The rise in atmopsheric CO2 is about half of anthropogenic emissions, and most but not all of the difference has ended up in the oceans. When the oceans and atmosphere have equilibriated there will be more of the "additional" CO2 in the oceans than the atmosphere though. –  Dikran Marsupial Apr 2 at 14:33
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@oddthinking sorry, I don't see how I have made any such implication, I thought I was just answering your question. I also didn't present my answer as scientific fact "I don't think that is the case..." is not the same as "scientific facts demonstrate that...". My answer was also that it was not true yet, but it will be when the carbon cycle has equilibriated, so your intuition was not wholly wrong. –  Dikran Marsupial Apr 4 at 8:06
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@Dikran: I hope you see I was being facetious; it is so hard to convey tone through text. I acknowledge your opinion makes sense to me, and given I have no strong substance behind my opinion, I bow to yours. (Of course, if someone cites from a peer-reviewed research, I'll bow to them instead.) –  Oddthinking Apr 4 at 8:23
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