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Tuesday, November 11, 2014

WUWT trips over p's and H's in the ocean

Sou | 8:06 PM Go to the first of 4 comments. Add a comment

Here's another teaser on oceans and acidification. I've got another article in train but have been busy, so it won't be up for a while longer. Meanwhile, WUWT has another "claim" article (archived here) about a not so new paper on ocean acidification,  total CO2 concentration and the degree of CaCO3 saturation (from June this year).

The paper itself is by a team led by Professor Taro Takahashi and has been published in Marine Chemistry. Anthony copied and pasted the press release but didn't have time to link to the source :) Never mind. It wasn't hard to find. The press release is on the website of the Earth Institute of Columbia University. I don't know why it has just been released. The paper itself has been out for a while. It looks to be a continuation of the work discussed in this paper from 2010, which itself built on work done prior. In fact, as stated in the press release, Taro Takahashi has been doing this research for four decades.

Taro Takahashi has spent more than four decades measuring the changing chemistry of the world’s oceans. Here, aboard the R/V Melville, he celebrates after sampling waters near the bottom of the Japan Trench in 1973. (Lamont-Doherty archives)

In a nutshell, the scientists have published maps of the world's oceans, showing:
... a monthly look at how ocean acidity rises and falls by season and geographic location, along with saturation levels of calcium carbonate minerals used by shell-building organisms. The maps use 2005 as a reference year and draw on four decades of measurements by Lamont-Doherty scientists and others. 

It's an impressive effort. I'd have liked  to write more about it but am a bit short of time this week. I was taken with these couple of paragraphs, which paint the picture and are almost poetic:
The vast tropical and temperate oceans, where most coral reefs grow, see the least variation, with pH hovering between 8.05 and 8.15 as temperatures fluctuate in winter and summer. Here, the waters are oversaturated with respect to the mineral aragonite—a substance that shell-building organisms need to thrive.
Ocean pH fluctuates most in the colder waters off Siberia and Alaska, the Pacific Northwest and Antarctica. In spring and summer, massive plankton blooms absorb carbon dioxide in the water, raising pH and causing seawater acidity to fall. In winter, the upwelling of CO2-rich water from the deep ocean causes surface waters to become more acidic. Acidification of the Arctic Ocean in winter causes aragonite levels to fall, slowing the growth of pteropods, planktic snails that feed many predator fish.

I've animated the two maps in the press release, which show pH and calculated omega of aragonite in February 2005.

Adapted from article Earth Institute, Columbia

You'll notice the blank strip across the middle of the Pacific Ocean. The explanation is in the abstract:
The equatorial zone (4°N-4°S) of the Pacific is excluded from the analysis because of the large interannual changes associated with ENSO events. 


Get the maps, and meet the scientist


I've discovered that you can access all the data and the maps from a page on the Columbia University website here.

You can also meet the great scientist himself - via YouTube:



Further reading


You may also remember that SkepticalScience.com has an extensive series of articles on ocean acidification - click here for the introduction and index.


From the WUWT comments


The WUWT-ers were very obedient and responded to the "claim" headline in a manner befitting the ignorant if motley lot of deniers. A lot of commenters don't understand what "more acidic" means. It means the equivalent of an increase in H+. Any time a solution has a drop in pH it can be said to have become more acidic or less basic (or less alkaline).


Gaz says:
November 10, 2014 at 4:07 pm 

Continuing your point about “since the industrial era began”, if this would infer that the Industrial Era began about 150 years ago, and the tone of the paper being that Man’s relentless CO2 emissions would carry on the decrease in alkalinity at the same rate. (0.1 decrease in pH units per 150 years). Would it not take 1650 years just to get to a neutral pH? Is there that amount of fossil fuel to burn for that period of time to create such a scenario?
No, Gaz. The oceans are very unlikely to ever have a pH of 7. The reason is buffering.


nielszoo doesn't do much better, writing:
November 10, 2014 at 2:24 pm 
Oh, and if the oceans are absorbing 25% of our “contribution” to CO2 (which is 3% and the rest of the changes are due to natural causes) then using their numbers we are responsible for 0.00075 lower PH to the drop in alkalinity.

nielszoo is wrong. We are responsible for the entire drop in pH. I don't know where nielszoo is getting his numbers from. Since industrialisation, the amount of atmospheric CO2 has increased from 280 ppm to 400 ppm (or approximately 0.04% of the air by volume). Human activity is responsible for the increase. CO2 is now 43% higher than it was before industrialisation. If we weren't chopping down forests and burning fossil fuels etc, there would have been no increase in CO2 and it would still be around 280 ppm. Thing is, if the oceans hadn't absorbed about 25% of the CO2 we've added to the air, then atmospheric CO2 would be around 430 ppm by now.


Tom Anderson doesn't understand that if there is more CO2, then, all other things being equal, the partial pressure will be higher. In this case, we are throwing CO2 into the air so quickly that the effect of the rise in partial pressure of CO2 is greater than the impact of the rise in surface temperature. That is why the oceans are still absorbing CO2 even while they get warmer. Tom wrote (extract):
November 10, 2014 at 2:46 pm
I am having trouble with the ocean absorbing more CO2, just because there is more of it in the atmosphere. I think I recall from Henry’s Law in high school that the amount of gas liquids can absorb depends on temperature and pressure, the amount of gas absorbed varying inversely with temperature and directly with pressure. It shouldn’t matter how much atmospheric CO2 there is, should it?
If global warming resumes and ocean temperatures rise, won’t the oceans release more CO2 and become more alkaline, not acidic? This seems more consistent with the Henry’s Law....

Tom is wrong. He's just looking at the temperature without considering the increased partial pressure of CO2.


Eric Worrall is looking for "anything but CO2" and writes, partly wrongly:
November 10, 2014 at 3:13 pm
Warm water is not capable of dissolving as much CO2 as cold water. The fact the very slight decrease in alkalinity is concentrated in the equatorial region suggests the source of acidification is not CO2 – more likely volcanic sulphuric acid.

Yes, it's a fact that CO2 dissolves more readily in cold water than warm water. I don't know what Eric's on about with the acidification at the equator and H₂SO₄.  As the IPCC reports state, the seas in the high latitudes have a lower buffer capacity (cooler and probably fresher water) than those of the low latitudes (warmer, more saline water), which is why the pH drop is greater in the high latitudes. Sulphuric acid, H₂SO₄, and nitric acid have both risen as a result of burning fossil fuels but have only localised effects in the oceans and are relatively insignificant on the global scale, compared to the effect of increased CO2. Sulphuric acid from volcanoes wouldn't make the oceans more acidic unless there was a big increase in volcanic activity. And there hasn't been. Otherwise it would be no different to what has been happening for the last several thousand years.


Then there's the usual contribution from the WUWT illiterati. The ones who are against knowledge. Who think that "edjukashun" and "lurnin'" is a complete waste of time, life and money. I'm surprised Leigh knows how to spell his own name. Maybe he doesn't. He could be Lee for all I know :)
November 10, 2014 at 2:10 pm“recommended that President Obama create a research and monitoring program dedicated to ocean acidification.”
I have never heard such utter over the top self serving crap.
Well I actually have.
I’m hearing it as their global warming grants are drying up.
Really, when will it end?
As one way to “milk” the cow becomes obsolete, they invent a whole new way to get a grip on the teat.
It has to stop!


Taro Takahashi, S.C. Sutherland, D.W. Chipman1, J.G. Goddard, Cheng Ho, Timothy Newberger, Colm Sweeney, D.R. Munro "Climatological distributions of pH, pCO2, total CO2, alkalinity,and CaCO3 saturation in the global surface ocean,and temporal changes at selected locations." doi: 10.1016/j.marchem.2014.06.004

Takahashi, Taro, Stewart C. Sutherland, Rik Wanninkhof, Colm Sweeney, Richard A. Feely, David W. Chipman, Burke Hales et al. "Climatological mean and decadal change in surface ocean pCO2, and net sea–air CO2 flux over the global oceans." Deep Sea Research Part II: Topical Studies in Oceanography 56, no. 8 (2009): 554-577. doi:10.1016/j.dsr2.2008.12.009

Takahashi, Taro, Stewart C. Sutherland, Colm Sweeney, Alain Poisson, Nicolas Metzl, Bronte Tilbrook, Nicolas Bates et al. "Global sea–air CO2 flux based on climatological surface ocean pCO2, and seasonal biological and temperature effects." Deep Sea Research Part II: Topical Studies in Oceanography 49, no. 9 (2002): 1601-1622. (link to paper)

4 comments:

  1. Sou, I'm sure you will discuss this in your upcoming article but I just want to add there's two forms of calcium carbonate. Calcite (most larger shell building organisms) and aragonite which is much more sensitive to increased pCO2. Here in Alaska, aragonite shell builders account for most of a juvenile salmons diet and unfortunately we're already seeing undersaturated water with respect to aragonite.

    http://www.sciencedirect.com/science/article/pii/S0079661114001141

    We're also getting a handle on OA in a coastal/nearshore sense for southeast AK. Unfortunately the second paper that describes what these regions are going to be like in 50 years isn't out yet (it will be soon, I work next to the person writing it), but I can tell you that we expect to see undersaturated water with respect to aragonite at all depths during all times of the year. In other words AK coastal waters especially in regions of high freshwater runoff are f**ked no matter what we do. First paper below.

    http://www.sciencedirect.com/science/article/pii/S0272771414000663

    ReplyDelete
    Replies
    1. If you happen to have the answer, could you please tell me why aragonite is more sensible to pCO2 ? A question of greater reactive surface compared to calcite, or something linked to the crystalline organisation ?

      Thanks in advance ! My chemistry is (unfortunately) far behind me, but I'm curious :) And wikipedia doesn't help me in this case

      Delete
    2. Hi, I just noticed your response! I asked the folks in my lab and they said it all boils down to the crystal structure, surface area and inclusions. The aragonite crystal structure has a larger surface area to volume than calcite thus making more area available for dissolution. I don't think there's been a lot of work in this area recently because it's more of a mineralogy question. I did however find this paper (of course my labmates told me to look it up myself) from the 1950's explaining the difference.

      http://pubs.acs.org/doi/abs/10.1021/ja01566a001

      They also mentioned that inclusions from various other minerals can also contribute to instability. I was able to find a paper about the role of magnesium in calcite/aragonite formation and I'm sure there's more out there.

      http://www.sciencedirect.com/science/article/pii/0016703775901027

      Feel free to email me at the address found on my school profile page if you have anymore questions. Cheers!

      https://www.sfos.uaf.edu/people/profile.php?uid=2844

      Delete
  2. Taro Takahashi painstakingly-collected and analysed surface ocean carbon work is the foundation of much of our understanding of the carbon cycle and ocean acidification. It boggles the mind that that WUWT denizens dismiss his work as based on "grant-seeking", instead of what it really is. A single-minded search for answers about how our earth works and how mankind's actions are changing it.

    As for solubility of calcium carbonate and related ionic structures, Bruce Railsback has produced and instructive plot showing the solubility of the important structures - http://www.gly.uga.edu/railsback/Fundamentals/820HMC-LMCSolubilities05LS.pdf

    ReplyDelete

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