Basic Geology Part 2 – CO2 in the Atmosphere and Ocean

Ferdinand Engelbeen (01:23:34) :
“Indeed it is possible that a lower pH drives out a lot of CO2, far more than temperature can do.”
I had been wondering about that very effect and it was the basis of a comment I made previously:
http://wattsupwiththat.com/2009/01/31/ocean-acidification-and-corals/
comment @ur momisugly 02/07/09 (16:20:24) : “which would win out in terms of effect [on CO2 release] – the 0.1 unit decrease in pH or say a 1ºC increase in temperature?”
I admit I should be able to calculate this myself, but I am far too lazy (these days the old brain works sooo slooowly). Also I was trying to complicate it by assessing the effect on CaCO3 formation too, since that also is less soluble at higher temperature, and more soluble at lower pH.
Of course the real ocean environment will be additionally complicated by local effects.

Foinavon – you have obviously never done any drilling!
I am a civil engineer and very infrequent commenter here, but I have been involved with many drilling programs in both soils and rock to try to understand foundation conditioions for large dams. We do very expensive drilling with constant expert supervision. We use downhole seismic and data logging and we know what we are doing.
We drill many holes and at the end we are inevitably unsure of exactly what we have and inevitaably it come down to expert interpretation, which is not always right.
If we can’t get it right on clay content, how can we possibly take ice core boring (almost certainly without constant, qualified supervision) gas content results as something that can be taken at face value?
The basic issue with drilling uis that you newver know what you are losing.
You possibly have have acceptable comparative values, but to extrapolate to global CO2 values is complete and utter nonsense.

Barry (10:25:24) :
I have posted this idea on another blog, and I’m sorry if it has already been covered here. Is it possible that the current increase in atmospheric CO2 is the result of the Medieval Warm Period 800 years ago? Since according to ice core data CO2 rises follow warming by 800 years or so.
The 800 years lag depends of the time periods involved. For the increase in temperature between a glacial and interglacial (in the Vostok ice core), the lag is 600 +/- 400 years, for the opposite cooling, the lag is many thousands of years, for the MWP-LIA cooling (in the Law Dome ice core), the lag is about 50 years and the current variability of CO2 around the increasing trend shows a lag of one to a few months after temperature variations…
The warm/cold/warm/cold periodicity over the Holocene shows variations of about 1°C which should give CO2 variations of about 8 ppmv from warm to cold and back, if we take the same ratio as seen in all ice cores for pre-industrial values. Thus not more than 8 ppmv extra from the deep ocean flows returning from the MWP…

Louis Hissink (10:42:08) :
Ferdinand,
Are you suggesting ice, say dated 1000 years old, has in it gas bubbles of a different age? Now that is interesting. I think I will accept the Polish interpretation for the moment.
When snow deposits, it contains open pores filled with ambient air. A lot of layers are settled over the years, but the pores still are open and can exchange molecules by diffusion. Slower as the pores are narrowing under the pressure of building up the snow/firn layers, but still going on, until the pores are completely closed. The average age in the gas bubbles can be calculated, as the diffusion speed for gases is known and the ice density / pore diameter at different depths can be measured.
In the case of the Siple Dome (used by Jaworowski as example of “manipulation”), the gas age was calculated by Neftel. In the case of the Law Dome, the gas age was measured by Etheridge in the different firn layers top down, confirming the calculations. In the layer where the bubbles were closing, the CO2 level was about 10 ppmv lower than in the atmosphere. With the atmospheric increase rate of that time, the average gas age is about 10 years older than the atmosphere. But at the same depth, there were already 40 years of snow/firn/ice layers counted. Thus the gas age is 30 years younger than the ice age at the same depth for the same ice core…
See: http://www.ferdinand-engelbeen.be/klimaat/klim_img/law_dome_firn.jpg
Closing depth is 72 m at Law Dome.
The gas age – ice age difference is mainly a matter of deposition: more snow and (relative) higher temperatures means faster compression and sealing, thus a smaller ice age – gas age difference. That is from 30 years for Law Dome to several hundred years for Vostok, with its low deposit rates.
That Jaworowski doesn’t know the difference between ice age and gas age in ice cores is not so good for his credibility as ice core sceptic, to say the least…

Dear Ferdinand,
you say: “It is near impossible to make a mass balance for the oceans with the small disturbance of human CO2 for the deep oceans”
and you did not refute my critisism regarding the pH-value.
It seems, that you rather agree to my critizism on your description:
A decrease of the pH-value is only known for the upper sea water, the C13-depleation cannot say anything about the mass balance!
From this perspcetive I cannot understand your answer about long time constants.
1) We seem to aggree, that it doesn’t take very long for the near surface sea water to atapt to the rise of CO2 in the atmosphere (with of course the local temperature dependent deviations) this of course works both ways, so if the deep ocean would be the main driver of the rise, we would see the same rise in the atmosphere and the drop in pH-value and C13-depletion would look the same (just to defute these invalid arguments for now and ever!)
I do understand your model, however there is still my question, how the assumed anthropogenic rise in CO2 work with the lack of sea water temperature . . And then you loose me a little bit . .
The life time of a CO2-mulecule is not related to the half life of a rise!?
Well let’s assume the near surface water is in close equilibrium with the atmosphere, then we have about 1500GTC CO2 in that system and exchange 100GTC per year with the deep sea reservoir, where you cannot give a mass balance . . And you say is does take very much longer than 7.5 years to exchange about 50% of the molecules at that rate? (Well it does, because we do have the other time constant of about 5 years, but the total time constant is less than the sum of both!)
What is wrong with that math?
And please let me know if you agree with my invalidation of your arguments up there, I see them repeated by you and others for years!
If they are unvalid, they obstruct a clear view to the science worth dicussing!
All the best regards,
LoN

Law of Nature (18:38:27) :
We do not need a mass balance for everything. We can make a mass balance of what happens in the atmosphere, which is what we are interested in, the rest is of secondary interest, but even then, the about 90 GtC exchange between atmosphere and upper oceans, the 50 GtC exchange between atmosphere and the biosphere over the seasons and the 100 GtC exchange between the upper and deep oceans and their unbalances can be used to make a flowchart of what happens roughly with the carbon cycles over a year. One of the many attempts to do that is here:
http://earthobservatory.nasa.gov/Features/CarbonCycle/Images/carbon_cycle_diagram.jpg
All based on (CO2, d13C, O2, current, deposits…) measurements but with large error margins (+/- 50% in absolute flows). Except for the total result in the atmosphere: we have a reasonable estimate of emissions, based on fuel sales and production figures (maybe somewhat underestimated) and a quite accurate measured increase in the atmosphere.
Thus whatever the height of any individual flows in/out the (deep) oceans and in/out vegetation, the net result is that the emissions are about twice the increase measured in the atmosphere, thus the sum of all natural flows in/out the atmosphere is negative and nature doesn’t add anything (in mass!) to the atmosphere, at least in the past 50 years…
If the (deep) oceans were a net source of CO2 (for whatever reason), then we have a mass balance problem, as the net result of any addition from the oceans + 8 GtC/yr from the emissions result in 4 GtC/yr measured in the atmosphere, while it should be larger than 8 GtC/yr. Except if vegetation would be a much larger sink, absorbing 8 GtC/yr + a part of the oceanic (net) releases to result in the 4 GtC/yr increase. But that means that vegetation should have grown with about 30% over the past 150 years…
While the d13C level doesn’t say much about the mass balance, it is a quite good indication of the source of the increase: the accuracy is fine enough to measure an addition of 4 GtC from the deep oceans or 1 GtC from vegetation or fossil fuel burning into the upper ocean level. As the d13C levels decrease, that excludes the deep oceans as main source (it dilutes the decrease with 10% per year, but doesn’t increase the d13C level) the increase in the atmosphere/upper oceans is either from vegetation decay or from fossil fuel burning (or both). But the oxygen balance shows that there is some O2 generation by vegetation, thus more CO2 uptake than decay since about 1990. Thus vegetation, which prefers 12CO2 to built in, is a source of 13C, not a sink. Thus all CO2 increase / d13C decrease we see is from fossil fuel burning…
That doesn’t mean that there are no huge exchanges between the different compartiments. But these exchanges don’t change the mass balance, as long as the inputs are equal to the outputs, which in general is the case, except when disturbed by year by year temperature changes (3-8 ppmv/°C) or human emissions (4 ppmv/year one way). The exchanges influence the residence time of individual (human or not) molecules, but it is the imbalance which influences the decay of an excess mass injection. Two completely different, independent half life times.

MartinGAtkins (09:18:12) :
“Man kind is only redressing the balance by releasing some of the previously buried carbon.”
I agree totally and have been thinking this since the second week I started looking into what this whole global warming thing was all about.
The idea of man as a Carbon Farmer is something I’ve attempted in my modest artwork. I just haven’t hit on the exact way to present it yet.
But the image of coal miners and, heaven forbid, Exxon Mobile guys on an oil rig as beneficial Carbon Farmers would be so offensive to some quarters that the temptation to do something along those lines is mighty appealing. 🙂

Law of Nature (18:07:22) :
How can you have an elevated CO2-concentration in the atmosphere and a temperature rise in the sea water less than 10K and NOT dump the CO2 in the deep sea?
If I understand you correctly you are also trying you construct some long time constants, but that doesn’t seem correct as a significant part of the reservoir is exchanged every year and that includes that a significant part of any rise is removed per year too!
Sorry for the delay in response, was a few days off…
OK, let us forget the upper oceans and vegetation, but concentrate on the deep oceans…
The largest sink, directly into the deep oceans is in the North Atlantic, where atmospheric CO2 goes directly down with the THC. The largest source is in the tropic Pacific, where the THC returns to the surface. That was so for as long as we can reconstruct the flows from the past.
What happens when we have a steady state temperature? The amounts of CO2 released by the warm waters round the equator and the amounts absorbed by the cold waters around the poles are equal and don’t add or substract anything to/from the atmosphere, although a continuous amount (maybe 30 GtC/year) of CO2 is flowing from the equator to the poles. The deep oceans don’t change either, not in composition, not in amounts.
Now we increase the temperature with 1 K, uniform over the whole ocean surface. What happens? The increase in temperature causes more releases of CO2 around the equator and less absorption of CO2 around the poles. As result of that, the CO2 level will increase in the atmosphere, but that has the opposite effect of the temperature increase: less release in the tropics, more absorption near the poles. Until everything again is in equilibrium (at a higher CO2 level in the atmosphere). Does that change the upper oceans? yes a little more CO2 will be found there and a little lower pH but no practical change in d13C. But the increase of CO2 in the atmosphere will have an oceanic fingeprint: a small increase in d13C level.
Does that change the deep oceans: not at all, the quantities released to bring the atmosphere into equilibrium with the oceans again are negligible compared to the mass of carbonate in the oceans.
From the pre-industrial past it is known that the change in CO2 introduced by 1 K temperature change is about 8 ppmv/K, over periods of decades to millennia. That includes everything, thus also possible changes in deep ocean currents and thus the amount of CO2 braught into the atmosphere and deep ocean CO2 sinks.
Now we add a lot of CO2 each year from fossil fuel burning. That is added to the atmosphere, thus increasing in first instance the CO2 level there. Thus reducing the normal release of CO2 from the warm oceans and increasing the uptake by the cold oceans, until the uptake by the oceans (if ever) is in equilibrium with the addition in the atmosphere by fuel burning. At that moment as much CO2 is absorbed by the oceans (released – absorbed) as is emitted by humans.
Does that change the amounts or d13C of the deep oceans? Not measurable, except if you burn all oil and a large part of the coal on this earth… Does that alter the d13C level of the atmosphere? Yes, that will decrease, but with less than calculated from fossil fuel burning, as a lot of (higher d13C) CO2 still is exchanged each year between deep oceans and atmosphere and back. The ratio between (human) addition and (deep ocean) circulation is what fixes the ultimate d13C level in equilibrium.
Thus the d13C level is a clear indication that the increase of CO2 in the atmosphere is NOT from the deep oceans (no matter the amounts exchanged over the seasons and years), but from the burning of fossil fuels.
If you can reduce the atmospheric CO2 by 15% in 10 years tim, but still burn fossil carbon, the total amount would reduce by 15% (as total mass), but the d13C level stil would remain as low (in ratio with addition and cycling masses), independent of the deep ocean non-changes…