Update - I've updated the archive here, just so anyone interested can read the comment from the batty duke (rgbatduke). See below.
Update 2 - Willis has added a new chart and now has another question - Click here to jump to it.
Wondering Willis Eschenbach is wondering again. This time he's wondering about carbon dioxide in the sea surface and the air (archived here, latest archive here). He used data analysed by the following team, that was collected way back in the 1950s and 60s:
Lee S. Waterman, Pieter P. Tans and Todd Aten from NOAA, Boulder, Colorado; Charles D. Keeling from Scripps Institution of Oceanography, La Jolla, California and Thomas A. Boden from the Carbon Dioxide Information Analysis Center, Oak Ridge, Tennessee.
A gigantic geochemical experiment...
The paper that Willis linked to provides an interesting piece of scientific history. It has a quote on the front page:
"...Man, in his burning of fossil fuels and denudation of the land's surface, may be performing a gigantic geochemical experiment in which the CO2 cycle is being influenced. It is thought we may be increasing the C02 input into the atmosphere by 70% in 40 years, although it is not certain how much of this may be absorbed by the oceans. A substantial increase in C02 content in the air would trap more of the earth's radiated heat and cause a warming of temperature.
Data collected during the IGY will be needed for comparison with measurements made 15 to 25 years from now to determine whether the C02 content is changing ..."
Lill and Revelle
Early ocean CO2 research
What the researchers did was analyse data collected in three oceanographic expeditions between October 1957 and August 1963. The data related to carbon dioxide in the air and the surface water. (IGY was a major international collaborative scientific effort between July 1957 and December 1958. From Wikipedia - "It marked the end of a long period during the Cold War when scientific interchange between East and West had been seriously interrupted".)
It didn't take me long to find what was probably Willis' source. The research is described by Scripps CO2 Program as:
During the late 1950's and early 1960's, Charles D. Keeling supervised the measurement of pCO2 in surface ocean waters and in the atmosphere just above on a number of seagoing expeditions mounted by Scripps Institution of Oceanography. These expeditions ("cruises"), comprising long transects in the major oceans, were chosen to map the global features of surface ocean pCO2. Data from most of these cruises are presented here for the first time in detail (in the form of hourly averages). The data had been processed soon after the cruises and presented in several research articles as averages, over geographical areas, of the difference in CO2 concentration between ocean and atmosphere (see References). This site contains data from the DOWNWIND cruise in 1957, the MONSOON cruise in 1961, and the long LUSIAD cruise in 1962 and 1963.
The wrong end of the stick
Willis took the difference between the air and sea surface CO2 data, which he mistakenly thought was parts per million by volume of CO2, and plotted it against sea surface temperature. (He obviously didn't read the above paragraph or the paper very closely.)
To describe the situation in another way, when the water is cool, it contains less CO2 than the overlying air … but when the water is warm, it has more CO2 than the overlying air.
Say what? I gotta confess, I have little in the way of explanations or comprehension of the reason for that pattern … all suggestions welcome.
In fact, as Nick Stokes pointed out in the comments, the data Willis used wasn't the amount or parts per million by volume of CO2, it was the partial pressure of CO2 (pCO2). So Willis' positives meant CO2 was going from the sea to the air (which is expected as water warms up) and his negatives going from air to sea, not the other way around - which was what Willis mistakenly thought. No wonder Willis was wondering why his chart was counter-intuitive.
There is more that is wrong with Willis' chart, but because his main error was so fundamental, he probably wouldn't have plotted the data that way if he had understood what the data was. So I won't go into that.
About ocean CO2
Ocean CO2 data have since been collected over the years by individual scientists or research teams. Now there are attempts to coordinate efforts globally, as described on the Global Observing Systems Information Centre (GOSIC) website.
CO2 dissolves fairly readily in water. Once in the water it reacts chemically and there's only a small bit that remains as CO2. As described at GOSIC:
The CO2 and associated chemical forms are collectively known as dissolved inorganic carbon or DIC. This chemical partitioning of DIC affects the air–sea transfer of CO2 as only the unreacted CO2 fraction in the sea water affects the CO2 flux, which is determined from measurements of atmospheric and surface sea water partial pressure of CO2 (pCO2) and wind speed.
The surface ocean partial pressure of CO2, pCO2, is a critical parameter of the oceanic inorganic carbon system
- because it determines the magnitude and direction of the exchange of CO2 between the ocean and atmosphere, and
- because it is a good indicator for changes in the upper ocean carbon cycle.
In addition, it is an oceanic parameter that can be routinely measured with high accuracy and precision.
The oceans are absorbing about 30% of the CO2 we are adding to the air (and the biosphere is absorbing about 25% of the extra CO2). The amount of uptake is affected by ocean modes such as the North Atlantic Oscillation, the Pacific Decadal Oscillation and ENSO. For example, in El Nino years, the oceans absorb a about 30% more than the long term annual average (which according to this 2010 paper by Valsala and Maksyutov is estimated at around 1.5 petagrams of carbon a year).
Here's a map from CDIAC showing the mean annual net air-sea CO2 flux as measured in 2000. Click for larger view.
|Source: CDIAC Ocean CO2|
Here's some more information from CDIAC about the differences in the CO2 absorption in different parts of the oceans.
Major source of CO2: The equatorial Pacific (14°N-14°S) is the major source for atmospheric CO2, emitting about +0.48 Pg-C/yr.
From the WUWT comments
November 27, 2013 at 2:55 am
Can it be a agw survey? Cold water absorbes CO2 and warm water let it go by out gassing. It looks to me that someone wants to let look to work the other way to help agw.
November 27, 2013 at 3:23 am
Relative difference is not the same as absolute. Warmer water can absorb and hold more CO2, than cold. The rate of change I more a question of kinetics.
November 27, 2013 at 3:25 am
The vast majority of their dots are for sea surface temperatures greater than 20ºC.
Perhaps the cruises in oceans where this was the case were more popular with the psyentists than those trawling around oceans with temperatures below 10ºC?
Or maybe the latter group just kept warm and cosy below decks?
November 27, 2013 at 4:02 am
Willis, I don’t think the water measurement reflects concentration of CO2, and I’m sure it isn’t ppmv of water. It’s described in your link as pCO2, which would be the partial pressure of CO2 in equilibrium with the seawater.
In that case, there’s no particular expectation about variation with temperature. With no flux, it would be zero at any temperature. What it does reflect is which way CO2 is moving.
November 27, 2013 at 4:42 am
I like to make soda water. Thinking very cold water would make bubblier soda that’s what I tried. Results not good! Then I tried water from tap around 20C. Result nice bubbly sodas. Seems the warmer water absorbs more CO2 more easily. Its been bothering me why?
François is impressed by the scientific research done 55 years ago and says:
November 27, 2013 at 4:11 am
Five years of measurements, fifty years ago, with the instruments available then. I am impressed.
Dodgy Geezer is a conspiracy theorist too and, after quoting Willis, says it's all a political plot:
November 27, 2013 at 4:39 am
…The first surprise was that I was under the impression that there was some kind of close relationship between the atmospheric CO2, and the CO2 in the surface seawater. …Alas, Willis, you have been infected by IPCC reasoning. The idea that there are only a few big variables and they interact with each other in a simple manner is what you say when you are a political advisor hoping to persuade a politician.
“Yes, Mr Prime Minister – if you enact this law you WILL get more votes…”
In reality we have two domains here, the sea and the air. Each has a set of pressures and balances which determine the local CO2 concentration. At the point where they touch – the sea surface, they probably interact with one another. But how important that interaction is compared with their own internal driving variables… who knows?
UpdateI've updated the archive (and again here) because there is a very long comment by the batty duke (rgbatduke AKA Robert G Brown. Don't worry, I'm not outing him. He hasn't hidden his identity at WUWT). I have to wonder how he got and managed to hold onto a job at Duke University. He doesn't seem to be aware that the data is from samples collected 50 years or so ago. He says he would have brought on-boat computers and automated robots! In 1957! And he wants the data compared to CO2 at Mauna Loa - which didn't start measuring CO2 until 1959. And despite the fact that quite a number of people mentioned it, the batty duke is also oblivious to the fact that Willis made a mistake and the data was pCO2 not ppmv CO2.
There's worse still. From his ivory tower at Duke, the batty one writes:
...but I’d bet my sweet bippy that it also reflects the selection bias of researchers to prefer ocean cruises in the warm, sunny tropics with lots of interesting places to stop and things to see relative to cruising around the Cape of Good Hope or Tierra del Fuego or knocking around Iceland or the Bering Straits — presuming one can get in through the ice and so on.
What a nong. If he'd checked the paper he'd have seen from the map of the routes that voyages went from around 70S to 35N and virtually all around the globe from east to west. They did sail around the Cape of Good Hope and while they didn't go around Tierra del Fuego, they went pretty far south in South America and right down near the Antarctic. (How many American scientific expeditions travelled around the Bering Strait during the cold war?)
Not only that, the batty duke has no appreciation of how real live scientists do field work - and the way that so many of them risk all sorts of dangers and put up with all sorts of hardships, so idiots like the batty duke can figure out whether to bring a brolly to work or will need to put in more firebreaks or add a water tank to his comfy home in North Carolina.
Willis has added more to his post including another chart and has another question (archived here). This time he asks:
My main question in all of this is, how does the CO2 content of the seawater get to be up to 100 ppmv above the CO2 content of the overlying air? It seems to me that the driver must be biology … but I was born yesterday.I came across an older paper that examined ocean CO2 in more detail, including looking at seasonal and diurnal fluctuations. The paper stated:
These results support that the diurnal change in pCO2 measured in the present study are associated with the photosynthetic activity by photoplanktons in seawater.
From what little I've read so far (and it's a huge subject area of which I haven't scraped but a fraction of the surface) the seasonal variation is driven by temperature but this varies by location. There are other factors that play an important role including upwelling / downwelling water (vertical mixing) and wind. There is also spatial variation that is driven by biological factors (which themselves vary with the season) and which combine with the effect of sea surface temperature.
Willis has simply plotted pCO2 vs sea surface temperature. He hasn't plotted by space (lat/long) or season. In his plot where the sea surface temperature is above 25 degrees and more particularly so when it gets closer to 30 degrees, pCO2 (ocean surface) is generally above the average atmospheric CO2 pressure. But I don't think that tells much.
What I don't understand is why Willis goes and plots all this stuff with no apparent particular aim in mind without doing any reading. You'd think being chided by Roy Spencer would have taught him a lesson.
L.S. Waterman, P.P. Tans, T. Aten, C.D. Keeling, and T.A. Boden, Quasi-simultaneous CO2 Measurements in the Atmosphere and Surface Ocean Waters from Scripps Institution of Oceanography DOWNWIND, MONSOON, and LUSIAD Expeditions, 1957-1963, draft report, 38 pages, 1996.