Ocean Acidification and Corals

@ur momisugly Steven Goddard,
“Chris J,
If you look at the “calculated” pH data, it has an extremely high standard deviation,”
Sure, seasonal changes in primarily primary production and secondarily a few other factors (e.g., salinity, net community calcification, etc.) produce a fair amount of deviation around the trend, though in absolute terms it’s a relatively modest amount of variation.
“…does not correlate well with the measured pH data in coincident years,”
Do you still not understand that these data represent different water masses?
“…and shows a large inexplicable drop in pH from 1989-1994 (before the measured pH data set started.)”
Au contraire, the drop in pH is easily inexplicable: pCO2 for the seawater increased ~10 uatm. See the trend in pCO2 here (select pCO2 comparison): http://hahana.soest.hawaii.edu/hot/trends/trends.html
“That drop, plus inconsistent low calculated readings the last couple of years accounts for almost their entire claimed trend.”
Yes, the drop in pH from 1989-1994 plus the drop from 1994-2007 accounts for the drop in pH. I mean, is that somehow surprising?
“The calculated data shows variations as high as 0.8 during time periods when the measured data has a peak variance of only 0.2.”
Sure, the ‘measured’ dataset is only a subset of the ‘calculated’ dataset. The ‘calculated’ dataset covers a larger spatial volume—you’d expect it to have a higher variance.
“I am surprised that they would include such an obviously flawed data set in their trend analysis.”
Ha, Steve, there’s absolutely nothing wrong with the data. They are what they are, and they’re freely available to you. Whether or not you like them doesn’t particularly matter.
The trendline for the pH data shows a mean 0.025 reduction in pH over the last 20 years at Aloha, with a s.d. almost as large. Clearly seasonal and interannual variation in rainfall (salinity, total alkalinity), primary production (dissolved CO2), calcification (total alkalinity, dissolved CO2), etc., all affect instantaneous chemistry parameters. This small reduction in pH is not something we much worry about, and if 0.025 units was the extent of the problem I would see no reason to worry much about this issue. However, this small reduction in pH ISN’T what we’re concerned about.
Since the preindustrial atmospheric pCO2 has risen form ~285 to 385 uatm. Standard seawater in equilibrium with those atmospheres (mean chemistry parameters in the shallow ocean are essentially in equilibrium with the atmosphere) would give seawater scale pH values of 8.15 and 8.05, respectively. This 0.10 unit reduction in pH, four times what can be seen in the HOT datasets, is more concerning, but even that is not enough that I think it a major problem.
The problem here is really the effects of a pH reduction (and changes in other chemistry parameters induced by it) in line with what we’re on track to see later this century. Given current rates of increase of atmospheric CO2 we’ll easily top 700 uatm by the end of the century, and could very well top 840 uatm for a value ~3x preindustrial. For standard seawater that gives a mean pHsws = 7.76.
The concern is not a 0.025 pH unit decrease, or even so much a 0.10 unit decrease, it’s the overall ~0.39 unit decrease (and related changes in chemistry) we’re on track to reach by the end of the century.
Again, look at the big picture here.
Chris

@ur momisugly Glenn,
“Steven Goddard (19:28:19) :
This is almost funny. I already provided the documentation of how ph is measured from the HOT site (below). Now I’m not betting the farm on that being correct, but it is more than Chris has done.”
Here you are: http://hahana.soest.hawaii.edu/hot/methods/ph.html
“But his latest reasoning has sent me into orbit. The earlier years weren’t measured because they didn’t have the instruments,”
As I said, the methods did not exist—spectrophotometric seawater pH methods with m-cresol purple were published in 1992 (Clayton and Byrne, 1992), therefore could not have been used when they started taking data in 1989.
“…the way he claims “calculated” comes from is superior to the “measured”, “measured” and “calculated” are taken from different and more depths, anyone could go back and recreate the same results… this all seems to be lipstick on the pig.”
Please feel free to double check those claims then, be my guest. Accuracy and precision for pH determination are both better by calculating pH from TCO2, TA, S, P, T, TP, TSi, using the analytical methods they use, than what you get from electrodes. You don’t have to believe me you can verify the claim yourself
“And none of it makes sense when one looks at the graph.”
What do you want me to tell you: I didn’t make the figure.
“Going back and recreating is trivial with the values recorded (if they are), but it is doubtful the actual samples are saved so that they could be retested.”
Well of course the water samples haven’t been saved, the data has.
“Doesn’t legitimize the graph. The only thing that could be tested is the math.”
Which is why standards are run along with the samples, to ensure accuracy and precision of the methods WHILE the data are being taken.
“The “measured” has a gap in the middle, so they did have the means at that time, but it is absent. Chris doesn’t address that.”
There are no spectrophotometric pH data from this time period, to the best of my knowledge. If you know of some, great, please provide the link/reference.
“Including two sources of data which come from different depths and including both on one graph would be just downright unprofessional, worse than sloppy.”
Why? You can’t put more than one dataset on a figure? If you’re unhappy with the figure, fine, download the data and create your own.
“If the method he claims is used for “calculated” is superior to any other, there would be no reason to include the “measured” to the graph at all.”
There’s more than one way to skin a cat, and more than one way to measure pH (with varying degrees of confidence, of course). Again, if you don’t like the figure, download the data and create your own.
“Certainly the two do not support a single trend. They are at odds.”
Really? Could you please show me the stats that demonstrate the two datasets show significantly different trends? Thanks!
“Chris hasn’t provided any reasoning for why the two measurement exist on the graph, and neither he nor Phil have responded to any of these concerns,”
Why are they on the same figure? Well, my guess would be so that they could put all the available data for the mixed layer on a single figure, instead of having to make two. But far more importantly, why in the world would it matter if these data are on the same or on different figures? What concerns have I not responded to?
“Chris hasn’t documented any of his claims, yet he accuses you of ignoring data.”
Are you joking? What claims have I not documented. Steven IS ignoring data. He’s made the de facto statement that because he doesn’t understand how one calculates pH data form TCO2, TA, S, P, T, TP, TSi, he’s throwing it out. Sorry, but no, one doesn’t get to ignore data because they don’t understand it.
“the graph (select pH comparison):
http://hahana.soest.hawaii.edu/hot/trends/trends.html
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.””
Agreed, that is curious. For instance, see: http://hahana.soest.hawaii.edu/hot/methods/ph.html
I’m fairly certain that the ‘measured’ = spectrophotometric, but let me double check references to be sure.
Chris

Chris J,
The point you are missing about the ocean system is that it contains large amounts of CaCO3 which buffer the alkalinity. Any push towards lower pH causes CaCO3 to dissolve, bringing the pH back up again. That is one reason why 5.2pH or less rainwater can continuously fall in the ocean, without any change in ocean pH. BTW – If ocean water did not circulate efficiently (as some have claimed) there would be an acidic layer near the surface, due to the rain. Instead, we find that pH decreases with depth.

@ur momisugly Glenn,
“Glenn (21:11:23) :
Chris J,
“The point I was making evidently did not come across. Calcite and aragonite are chemically different.”
No, Chris, they are not. Pure calcite has the same chemical composition as pure aragonite. When mixed with impurities, they are not pure. But when you say “calcite”, you shouldn’t mean magnesium calcite. It isn’t hard to understand, or convey.”
Oh good lord Glenn–“pure” calcite and aragonite (pure being defined as without impurites/inclusions) do not exist. That’s the point! In the real world low-Mg calcite, aragonite, and hi-Mg calcite (of which there is quite a range of compositions) all have chemical differences among them that significantly affect a variety of physical and chemical properties. In addition, the distinct lattice structures impart additional differences in physical properties.
These three minerals are not remotely the same things, physically nor even chemically. They are chemically similar, but certainly not the same.
Chris

J Lo, I did the math for seawater a couple of days ago and found you were right then got swamped in something else. I apologize. Cheers.

J Peden –
If you increase the H2CO3 by some defined amount and work out the algebra using the equilibria equations you will be convinced!

@ur momisugly Steven Goddard,
Steven, you’re so wrong about the things you’ve written here (below), it’s utterly shocking. Honestly, you nearly made my jaw drop. See below for a bit of reality.
“Chris J,
The point you are missing about the ocean system is that it contains large amounts of CaCO3 which buffer the alkalinity. Any push towards lower pH causes CaCO3 to dissolve, bringing the pH back up again.”
Steven, do you honestly think I and the rest of the scientific community have not considered the effects of CaCO3 dissolution? Let us entertain your claim that “any push towards lower pH causes CaCO3 to dissolve, bringing the pH back up again” for a moment.
If it were true that the addition of CO2 to the ocean when solid CaCO3 is present is simply compensated by CaCO3 dissolution, it would be impossible for atmospheric CO2 to ever change. Think about it: any change in atmospheric CO2 would simply be compensated for by CaCO3 dissolution/precipitation. If the mechanism you’re suggesting (fast response time for CaCO3 to change in atmospheric CO2) were real the atmospheric CO2 concentration would have been constant on this planet over its entire history. To be blunt, even a moment’s thought would have made you realize how wrong that is. What then is the real response time like?
Rates of CaCO3 dissolution in the ocean are limited both spatially (i.e., most sea water is not in direct contact with CaCO3) and kinetically (CaCO3 dissolves slowly—lots of experimental data here). Rates of dissolution have been measured in a variety of environments (deep sea, carbonate banks, neritic zones, etc.) under a variety of conditions. Given measured rates of dissolution, oceanic circulation patterns, diffusion, equilibration, etc., how long will it take for enough CaCO3 to dissolve (and secondarily silicate weathering) to reestablish the aragonite/calcite saturation state near preindustrial levels, given our current trajectory of CO2 emissions. Are you ready for it?
On the order of 18,000 yrs is needed. To fully reestablish preindustrial rates of CaCO3 accumulation in the open ocean, including in the deep sea, we’re looking at 100,000+ yrs (Archer et al.,1998; Archer, 2005; Anderson et al., 2003; Caldeira and Wickett, 2003; Zachos et al., 2005). Reef-building, on the other hand, takes on the order of several million years to recover after such a perterbation (see a discussion in Veron, 2008).
Your contention that CaCO3 dissolution will keep pace with and buffer against CO2 acidification isn’t just wrong, it’s ludicrous. Don’t believe me, read the references (which one would’ve hoped you would do before you posted).
“That is one reason why 5.2pH or less rainwater can continuously fall in the ocean, without any change in ocean pH. BTW – If ocean water did not circulate efficiently (as some have claimed) there would be an acidic layer near the surface, due to the rain. Instead, we find that pH decreases with depth.”
Again, you’re so wrong it’s shocking. pH is not a conservative parameter—you can’t determine the pH obtained by mixing two solutions with a weighted average. Hence, your argument that oceanic pH doesn’t fall appreciably despite the addition of pH = 5.2 rainwater is a non sequitur.
In unpolluted rain water the only major acid is carbonic acid, derived from atmospheric CO2 (yes, I know you know this). That water is essentially unbuffered. When you add rain water to sea water you’re adding water and a bit of dissolved CO2 (and tiny bits of HCO3- and immeasurably little CO3=, in equilibrium) and that’s it. Since CO2 is less soluble in fresh water than sea water, the addition of rain slightly reduces the TCO2 of that sea water, nudging the system toward higher pH. However, the additional water dilutes the alkalinity, pushing the system toward lower pH. The overall effect for an addition of rainwater is small and is due entirely to the dilution of alkalinity: for a 1 ppt drop from 35 ppt to 34 ppt, pHsws would drop from 8.05 to 8.03 in standard sea water. This effect disappears as soon as the water evaporates and the alkalinity and salinity return to normal. There is no long term effect whatsoever.
The oceans circulate, but they don’t do so instantaneously. For an entire trip along the thermohaline conveyor belt it takes ~1500 years, and half that to turn over the entire mixed layer. If the ocean were completely stagnant below the mixed layer the addition of rainwater would do absolutely squat to long term pH. Since the only effect rainwater has on oceanic pH is a dilution effect on alkalinity, and that effect is counterbalanced by evaporation, long term not a darn thing happens.
Honestly man, I would recommend at the very least a rudimentary course in oceanography and aquatic chemistry/chemical oceanography. Your ignorance about the basics here is, frankly, breathtaking.
Chris

It is interesting how the AGW camp simultaneously claims that the oceans have lost their ability to absorb more CO2, and that increased CO2 absorption by the oceans will lead to acidification.
http://www.guardian.co.uk/environment/2009/jan/12/sea-co2-climate-japan-environment
The two arguments are mutually exclusive, but the first one is closer to the truth on short time scales. Increased acidity leads to dissolution of limestone (CaCO3) below the carbonate compensation depth, which leads to reduced acidity and release of CO2 back to the atmosphere.
That is how buffering works.

Steven Goddard (08:22:24) :
It is interesting how the AGW camp simultaneously claims that the oceans have lost their ability to absorb more CO2, and that increased CO2 absorption by the oceans will lead to acidification.
http://www.guardian.co.uk/environment/2009/jan/12/sea-co2-climate-japan-environment
The article you link to is titled “Sea absorbing less CO2…”
Did you just misread it, Steven? Or do you not understand the language?
The two arguments are mutually exclusive, but the first one is closer to the truth on short time scales.
Not so – the opposite is the case. On the shorter scale the oceans are still absorbing more CO2 than they are outgassing, on the longer scale the opposite is projected. You presume that buffering is effectively instantaneous, or at least very rapid. It is understandable, therefore, that you would think acidification impossible. A false premise will, of course, lead to a false conclusion.

@ur momisugly Steven Goddard,
“Chris J,
Disappointing to see you reduce yourself to to ad hominem attack, flat earth comparisons and self-promotion.”
Do you understand the nature of an ad hominem attack? An ad hominem attacks the qualities of the person advancing an argument, instead of the argument. I attacked your argument. Your argument attempts to refute long-settled understanding through a series of inaccurate or distorted statements, assumptions, or interpretations, just as flat Earth arguments do.
As for self promotion: I am anonymous here (I’m really a Chris J., but clearly my J. is not public information here). How can an anonymous person self promote?
“Your last comment pretty much sums up your confused state – your words: “These three minerals are not remotely the same things, physically nor even chemically. They are chemically similar
Besides being self-contradictory, you really have no idea what you are talking about, yet you speak so confidently.
From: http://encarta.msn.com/encyclopedia_761573488/calcite.html
Calcite and aragonite have identical chemical compositions, but the molecules are stacked differently in the crystals. When two minerals have identical chemical compositions but different crystal structures, they are polymorphs of each other. Calcite is generally more stable than aragonite. Over several years, most aragonite will change to calcite. Thus, newly created calcium carbonate deposits may contain some or even a lot of aragonite, but ancient deposits contain little or no aragonite.”
Let me speak very plainly: I am an active researcher. My area of research focuses on biomineralization, and secondarily on the effects of ocean acidification on marine organisms. Carbonate chemistry/biomineralization are my areas of expertise. I am telling you very plainly that low-Mg calcite, aragonite, and hi-Mg calcite, while chemically similar, are not identical, and these differences are important. Your citation of an encyclopedia article (written for lay audiences, and over-generalized in this case) is incorrect in stating that calcite and aragonite are chemically identical. If they were a great deal of the information we can glean from such skeletons/shells would not exist. Magnesium and strontium content are among the important differences among these minerals.
“It is interesting how the AGW camp simultaneously claims that the oceans have lost their ability to absorb more CO2, and that increased CO2 absorption by the oceans will lead to acidification.
http://www.guardian.co.uk/environment/2009/jan/12/sea-co2-climate-japan-environment
The two arguments are mutually exclusive, but the first one is closer to the truth on short time scales. Increased acidity leads to dissolution of limestone (CaCO3) below the carbonate compensation depth, which leads to reduced acidity and release of CO2 back to the atmosphere.
That is how buffering works.”
Steven, you either didn’t read that article, or didn’t understand what you read. The rate of CO2 absorption by the ocean has decreased, not stopped. The ocean is sequestering CO2 slower than it used to, but is still sequestering it. That’s what the article says, that’s what’s happening, and your misreading of it doesn’t change these facts.
Second, you evidently have no understanding of the effects of CaCO3 dissolution on CO2 sequestration. The dissolution of CaCO3 enhances, not reduces the capacity of the ocean to sequester CO2: CaCO3 + CO2 = Ca++ + 2HCO3-
Of course the response time for meaningful dissolution of CaCO3 is far, far too slow to have an significant impact this century, or for many to come (see post above and references therein).
I am again astounded by you lack of understanding, misunderstanding, and outright distortion of the very basics here. If you don’t understand even the rudimentary aspects of this chemistry, why did you feel qualified to write about it in the public square?
Chris

@ur momisugly Steven Goddard,
“Chris J,
You continue to make ridiculous claims. Rainwater doesn’t dilute the oceans. All of the acid rainwater evaporated from the oceans shortly before it fell back in. The system is in near perfect equilibrium over short time scales.”
Exactly the point I made! Your claim was that if the surface of the ocean were not rapidly turned over then rain (pH ~5.2) would reduce the pH of this surface layer over the long term. You were completely wrong, as I explained to you. Rain dilutes seawater, diluting alkalinity, and causes a small reduction in instantaneous pH as a result. This effect is counteracted by evaporation (concentrates alkalinity, raising instantaneous pH). There is no long term trend. That is the point I made to you!
“Secondly, the reduction in atmospheric CO2 over geologic time scales is because it has been absorbed into carbonate rock and removed from interaction with the ocean system.”
You’re astounding Steven. Just above you argue that the entire ocean is readily and rapidly buffered against CO2 addition by carbonate dissolution (which is nonsense, as I demonstrate above), and here you argue that the same carbonate minerals have been removed from interaction with the ocean system.
The same minerals that are available to reduce atmospheric or oceanic CO2 via chemical weather (silicates and carbonates) were always available. Long term variation in atmospheric CO2 has resulted due to a combination of geological processes and biological sequestration. Storage in carbonates is only one of the important sinks.
“Take a trip to the Grand Canyon and observe the thick white layer across the top – named the Kaibab Limestone. A few hundred million years ago, all that CO2 contained in the rock was in the atmosphere – and the sea floor was covered with shellfish and corals. Changes in atmospheric CO2 correspond to changes in ocean temperature and changes in the amount of CO2 sequestered in rock.
The rim of the canyon is formed of a layer about 300 feet thick called the Kaibab Formation. This creamy yellow limestone has fossils in it: sharks, fish, corals, brachiopods, bryozoans, crinoids and sponges, that tell us it formed in a shallow, warm, Caribbean-like ocean.
http://www.hitthetrail.com/geology2.php”
Steven, sequestration of CO2 in biogenic carbonates increases atmospheric CO2, it doesn’t reduce it. How do you not understand this? Only chemical weathering of existing carbonates and silicates draws down atmospheric CO2, not production of carbonates de novo.
Chris

Chris J,
I can see that you have no understanding of geology whatsoever. So I will start from the beginning.
During the Carboniferous period, huge deposits of carbonate rock formed and were removed from the ocean system. Much of this rock was uplifted above sea level. This corresponded to the 95% drop in atmospheric CO2 seen in the graph above during that period. Carbon was removed from the atmosphere through the formation and sequestration of carbonate rock. Your failure to understand this is somewhat bizarre.
H2O evaporates from the ocean continuously. It combines with atmospheric CO2 to form carbonic acid. Some of the acid rain falls on land, which dissolves silicatesand brings alkali metals like Ca, Na and K into the oceans. These combine with dissolved CO2 to form carbonate rocks.
There are also huge amounts of carbonates currently on the sea floor. These buffer the system from the acid rain and prevent the ocean from becoming acidic.
You wrote – “Only chemical weathering of existing carbonates and silicates draws down atmospheric CO2”
Quite the opposite. When acid comes in contact with carbonates, it releases CO2. Try mixing vinegar and baking soda to see this in action. This happens in caves and karst environments all the time. Some caves contain levels of CO2 that are hazardous to spelunkers.