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At a glance - Ocean acidification: Global warming's evil twin

Posted on 4 July 2023 by John Mason, BaerbelW

On February 14, 2023 we announced our Rebuttal Update Project. This included an ask for feedback about the added "At a glance" section in the updated basic rebuttal versions. This weekly blog post series highlights this new section of one of the updated basic rebuttal versions and serves as a "bump" for our ask. This week features "Ocean acidification: global warming's evil twin". More will follow in the upcoming weeks. Please follow the Further Reading link at the bottom to read the full rebuttal and to join the discussion in the comment thread there.

At a glance

Have you heard of ocean acidification? Does it mean that if you go swimming in the sea, you are liable to dissolve? No. You'll be OK because you are not a calcifying organism, such as a mollusc, a coral or a sea-urchin.

So why is ocean acidification serious? Because it can potentially lead to massive collapse of marine food-chains. Let's take a look at what the term means.

The pH scale, which measures acidity and alkalinity of water-based chemical solutions, runs from 0 (highly acidic) to 14 (highly alkaline), with pH 7 being the neutral halfway point. Importantly, the scale is logarithmic, meaning that a jump of one point towards zero means a tenfold increase in acidity.

Acidification simply means lowering the pH value from any point on the pH scale towards zero. It's similar to the way we talk about temperatures. If the pH of a solution shifts from 9 to 8, that is acidification, even though the pH is still on the alkaline side of neutral. Likewise, if the temperature rises from -40oC to -15oC, it has noticeably warmed, even though it's still darned cold.

Now, typical seawater is slightly alkaline at around pH 8.1. Rainwater, which always contains dissolved carbon dioxide (the old name for which was 'carbonic acid gas'), has a more acidic pH of around 5.6. You have likely visited or watched footage of spectacular caves, have you not? All carved out by carbonic acid, dissolving solid limestone over many thousands of years.

Carbonic acid is not only present dissolved in raindrops. It also forms by the dissolving of carbon dioxide at the air-water interface of our oceans. The more carbon dioxide in the air, the more goes into the oceans, driving their pH from 8.1 downwards. Now, the huge problem this creates, well before we get anywhere near the neutral value, is as follows.

Many marine organisms build and maintain their protective shells or skeletons from 'biogenic' calcium carbonate. The word biogenic means made by living things. These creatures extract the calcium and carbonate ions dissolved in seawater and combine them together. Under normal conditions, such calcium carbonate is stable in shallow waters. That's because dissolved carbonate ions are present in such high concentrations that the waters are said to be saturated with them.

But if seawater pH falls, even by a small amount, the concentration of dissolved carbonate ions falls. When that happens, biogenic calcium carbonate becomes more soluble and can start to dissolve. Depletion in dissolved carbonate ions thus makes it harder for such organisms to maintain their protective or skeletal structures. In the worst case scenario, the rate of calcium carbonate dissolution is faster than its formation. When that happens, mass-mortality of calcifying organisms can occur.

We're talking about critters that underpin entire marine food-chains here. Things from near-microscopic calcifying plankton to shellfish, lobsters and crabs the seafood we eat in other words. That's why ocean acidification is deadly serious.

Please use this form to provide feedback about this new "At a glance" section. Read a more technical version below or dig deeper via the tabs above

Click for Further details

In case you'd like to explore more of our recently updated rebuttals, here are the links to all of them:

Myths with link to rebuttal Short URLs
Ice age predicted in the 1970s
It hasn't warmed since 1998
Antarctica is gaining ice
CRU emails suggest conspiracy
What evidence is there for the hockey stick
CO2 lags temperature
Climate's changed before
It's the sun
Temperature records are unreliable
The greenhouse effect and the 2nd law of thermodynamics
We're heading into an ice age
Positives and negatives of global warming
Global cooling - Is global warming still happening?
How reliable are climate models?
Can animals and plants adapt to global warming?
What's the link between cosmic rays and climate change?
Is Al Gore's An Inconvenient Truth accurate?
Are glaciers growing or retreating?
Ocean acidification: global warming's evil twin

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Comments 1 to 25:

  1. When did the language of pH become focused on acidity ?  I posed the question to an AI ïf the pH of a solution changes from 9 to 8 what happens ? The answer was it becomes more acidic.  I rephrased the question to what happens when it changes from 4 to 5 and the answer was it becomes less acidic.  Shouldn't the current state determine the designation ?  How would you describe an ice cube in a freezer where the temperature has been adjusted from -20C to -2C ?  Would it be more liquid or less frozen ? 

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  2. Gordon, a state of being frozen or liquid is determined by a "phase change." The pH of a solution doesn't go through a similar phase change. 

    When you add CO2 to H2O you get H2CO3, or carbonic acid, which further dissociates into H+ and HCO3-. Regardless of where your solution is on the pH scale, that process is called "acidification."

    The "H+" is the key since pH is a measure of free hydrogen ions in a solution.

    I think I have that right.

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  3. Oh, Gordon @1. Not that old canard.

    In heading from London to Paris, are you going south? Or "less north"? How on earth can you be going south if you are north of the equator?


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  4. By the way, Gordon. We're still waiting for you to provide a definition of "catastrophic" on this thread here.  Don't think we've forgotten about your previous evasive behaviour on other threads.

    Have you read the Comments Policy yet?

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  5. Rob, Acid solutions are composed primarly of H+ ions.  Alkaline solutions are composed primarily of OH– ions.  Neutral solutions contain equal amounts of H+ and OH- ions. When I studied Chemistry (many years ago) we always described the pH of a solution based on its direction from Neutral - <pH7 more/less acidic >pH7 more/less basic.  

    Actually, after reading around it would seem that the term Ocean Acidification has more of a political connotation than a scientific one.

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  6. Bob, I've read the Comments Policy but I can't see anything about evasive behaviour ?  I did notice the offence of Dogpiling though !

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  7. Gordon:

    I see that (so far) you are evading the question about whether you are going south when you travel from London to Paris.

    If you read the "dogpiling" rule completely, note that "the moderator may designate one or two people from each side of the debate as the primary disputants". It applies to large numbers of people - usually arguing with one person. It most certainly does not apply when the number of opponents is small.

    As far as being evasive is concerned, please read the section on Sloganeering. It includes "Comments ... which contain no relevant counter argument or evidence from the peer reviewed literature constitutes trolling rather than genuine discussion." Completely ignoring counterarguments, and behaving as if they were never made, is not genuine discussion.


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  8. Bob, there is a time when one has to agree to disagree.

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  9. Bob @3, if you apply the logic that I was presented with @1 then by traveling from Sydney to Singapore you would going less South as you can never travel North !

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  10. If you actually read the Comments Policy, you would also see that "moderation complaints are always off topic and will be deleted".

    In other words, you don't get to disagree with the Comments Policy, Following it is not optional.

    Now, if you are saying you disagree that going from London to Paris is "going south", then you really need to make your comments more specific. Being specific helps honest discussion. Being vague and evasive does not.

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  11. Gordon @ 9:

    Let me introduce you to the equator, and the concept of north latitude and south latitude. It appears that this geographical concept is one that you are unfamiliar with.

    London is at 52N, Paris is at 49N.

    By the logic you present in #1, you cannot go south from London to Paris.

    And yes, it is perfectly reasonable to say that Paris is not as far north as London.

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  12. Gordon, perhaps you'll remember from your chemistry class that "pH" means, essentially, "the power of hydrogen." Right?

    The link you reference is Forbes, hardly a scientific journal by any stretch of the imagination, and one which is more prone to publishing politically motivated opinion articles. And that's exactly what you're reading there.

    No one has ever claimed the oceans are acidic, or have become acidic. No one has ever claimed anything other than the oceans are "acidifying," meaning exactly what it says. 

    You can literally be at a pH of 14, move a solution to a pH of 13, and that would acidification.

    The only possible other word one could use would be "debasification" but good luck finding that in any scientific research. Plus, that would clearly not describe the underlying process that's occurring.

    Bob's point, which you're avoiding, is appropriate. When traveling from NYC to Atlanta no one claims they're going "less north."

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  13. Bob, Rob,

    Lets call Acidic South and Basic North - using the logic of moving from pH 9 to 8 described as becoming more acidic (i.e moving South) then which direction are you travelling if the moves from pH 4 to 5 which is described as becoming less acidic ?  It has to be less South correct ?

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  14. ...and let's consider that acidic and basic are opposites, and "more acidic, less basic" or "more basic, less acidic" are interchangeable.

    Just like "London is north of Paris", and "Paris is south of London" mean exactly the same thing.

    It seems that all you have is word games.

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  15. Bob,

    Maybe it might be clearer if I go back to my original Analogy.

    A liquid can be acidic or alkaline.

    A liquid can be solid or liquid.

    When a liquid is solid we never discuss its properties as a liquid and vice versa.  The same should also be true when discussing pH.  

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  16. Gordon :  putting aside all questions of semantics & wordplay  ~ I must confess that I am failing to grasp the fundamental point which you might be aiming to convey.

    Scientists know that the ocean is undergoing acidification [or de-alkalinisation , if such a word exists].   However: "Acidification"  is the commonly-used term, which is understood by everyone having a scientific interest in the issue at hand.   Just as the (very imperfect) term GreenHouse Effect  is commonly-used and widely-understood [by the science-minded layman, too ].

    Words should be used to improve  communication ~ rather than be used to obscure whatever important point it is that you wish to discuss.  And what is that point which you wish to discuss here in this thread?   Please make yourself clear.

    [Your quote that a "liquid can be a solid"  (@15) is an example of poor communication.]

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  17. What was the name of that 1930's film? Oh, yeah...

    "Go less east, young man!" :-)

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  18. Gordon @15...

    Liquid/frozen and acidic/alkaline are not analogous being that the former has a phase change at zero celcius. The later is merely a definition of a range in pH with no phase change.

    Every time I've run into this entire argument (and it's been many times over) I always ask the other person to look at the scientific literature and see how the term "acidification" is used. I ask them to find any research that uses a different term. 

    Never has anyone taken up that task, and in the end I always do it for them. 

    The term is correct in its usage applied to ocean acidification. The term is consistent with other unrelated research. There are no other terms used that represent the same process. As Eclectic says, it is merely semantics to argue otherwise.

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  19. Eclectic,

    Exactly, words should be used to improve communication.  I bet if you asked anyone on the street whether the ocean was acidic or alkaline the common response would be acidic.  If you say acidification enough times its gonna stick.  If you look HERE the takeaway will be that the ocean is becoming more of something it is not !

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  20. Gordon #1, #19

    I've known about acidification for some 45 years - since I started doing science at school and took that to A level. But what about people who bunked-off science classes in their teens and have only encountered acid in car batteries?

    I bet if you asked anyone on the street whether the ocean was acidic or alkaline the common response would be acidic.

    I wonder? Hopefully not if they have read the at-a-glance intro to the topic, where I first mention the pH of seawater with, "Now, typical seawater is slightly alkaline at around pH 8.1"

    I don't know what AI you have used but it would be instructive to see what it made of taking a solution from pH 5 to pH 9 - well into the alkaline side of neutral - not that AI is reliable. It tends to tell you what you want to read! But your exercise (Ph 4 to pH 5) only takes a stronger acid to a weaker acid. The solution is still on the acidic side of neutral.

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  21. Gordon @19 ,

    Yes, "acidification"  has well and truly "stuck".  And the ocean is changing in its physical reality of H+  and OH-  ratio (and is changing so rapidly that it is causing adverse effects in the marine molluscs & calciferous micro-fauna, etc.  That change might not matter 10,000 years in the future . . . but for now it is worthy of attention).

    So . . . putting aside your abstract interest in different words  ~ what is the substantive point that you wish to make?

    [ Gordon, I hope you do not represent some ChatGPT-like group, who is simply aiming to improve on AI language skills.  The thread here is about scientific & practical problems of rapid acidification of the planetary ocean. ]

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  22. I think if you asked anyone on the street whether the ocean is acidic or alkaline the top answer would be "I don't know."

    I imagine ocean acidification has a fairly low awareness level in the general public compared to climate change.

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  23. John @20

    Headlines this THIS dont help the cause.

    AI reports 5 - 9 correctly as basic.

    4-5 less acidic

    9-8 more acidic

    Yes, the ocean is alkaline but it will never be acidic.

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  24. Gordon #23,

    The closer towards neutral the oceans become, the more compromised calcifying organisms will be.

    And we're talking about whole fisheries and people's livelihoods here. This is no laughing matter. Nitpicking the choice of words in a newspaper headline is, in that context, trivialising a very serious situation. Note also that journalists - typically sub-editors - write the headlines, not scientists.

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  25. From Woods Hole Oceanographic Institution :

    One of the most common negative responses Sarah Cooley gets when she speaks to community groups about ocean acidification is, “What do you mean, ocean acidification? The ocean is not acidic! Seawater is never going to get below pH 7—so you must not know what you’re talking about.

    That’s partly true, said Cooley, a postdoctoral researcher at Woods Hole Oceanographic Institution. The pH of seawater is near 8, which makes it mildly alkaline, or basic; but any decrease in the pH of a liquid is considered “acidification.”

    “It’s a lot easier to say ‘ocean acidification’ than ‘ocean de-alkalinization,” said Cooley.

    pH is an index of how many protons, or hydrogen ions (H+) are dissolved and free in a solution. The pH scale goes from 0 to 14. A fluid with a pH of 7 is neutral. Below 7, it is acidic; above 7, it is alkaline.

    A small drop in pH means big change in acidity: The pH of seawater is near 8, which makes it mildly alkaline, or basic; but any decrease in the pH of a liquid is considered “acidification.” The key danger factor is an increase in dissolved hydrogen ions.(Woods Hole Oceanographic Institution)

    The more below or above 7 a solution is, the more acidic or alkaline it is. The scale is not linear—a drop from pH 8.2 to 8.1 indicates a 30 percent increase in acidity, or concentration of hydrogen ions; a drop from 8.1 to 7.9 indicates a 150 percent increase in acidity. Bottom line: Small-sounding changes in ocean pH are actually quite large and definitely in the direction of becoming less alkaline, which is the same as becoming more acidic.

    If you think about it, we use descriptive words like this all the time. A person who stands 5’5” tall and weighs 300 pounds isn’t thin. If he loses 100 pounds, he still won’t be thin, but he will be thinner than he was before he went on the diet. (And we are more likely to comment that he’s looking trimmer than to say he’s not as fat as he used to be.),150%20percent%20increase%20in%20acidity.

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