I’ve been doing some more than usual research as of late to answer for myself a specific question about CO2 respiration and the amount of man-made CO2 that is reatined versus naturally generated CO2. In doing so I’ve been in some discussion with some people I share an email list with.
One of them pointed out this ESRL (Earth Systems Research Laboratory) animation to me. I immediately found it intriguing because of the disparity between hemispheres:
CO2 (C13) January 1996 to December, 2007
From ESRL:
This movie shows the latitude distribution (from south-to-north) of average monthly values derived from the GLOBALVIEW extended records. Cyan circles are average monthly values from sampling locations thought to be regionally representative; pluses are average values from locations thought to be influenced by local sources and sinks. A smooth curve is fitted to the representative measurements when sufficient data exist.
Isotopic measurements from NOAA air samples are made by the University of Colorado (CU), Institute of Arctic and Alpine Research (INSTAAR), Stable Isotope Laboratory (SIL).
They caution that this is a derived product, (due to processing, smoothing etc) and does no longer represent raw data on CO2C13, along with other caveats such as this:
These and other measurements have been widely used to constrain atmospheric models that derive plausible source/sink scenarios. Serious obstacles to this approach are the paucity of sampling sites and the lack of temporal continuity among observations from different locations. Consequently, there is the potential for models to misinterpret these spatial and temporal gaps resulting in derived source/sink scenarios that are unduly influenced by the sampling distribution. GLOBALVIEW-CO213 is an attempt to address these issues of temporal discontinuity and data sparseness and is a tool intended for use in carbon cycle modeling.
But still, it is quite informative. Here is a map of the ESRL station distribution. Not all of them are CO2 surface monitoring stations.
Note how the southern hemisphere’s (90S to EQ)CO2C13 content remains nearly steady over the 12 year period, while the northern hemisphere shows major seasonal variation. The greatest variation is at the northernmost latitude, with data that likely comes from the Alert, Nunavut, Canada and the Ny-Alesund, Svalbard ESRL monitoring station.
You can see by the seasonal variation in the movie that when it is warmer, more CO2C13 is being released into the atmosphere, when it is colder, more CO2 C13 is taken out. It demonstrates a short term linkage between CO2 and temperature. While the “paucity of sampling” in the Southern Hemisphere is evident from the map, I find it curious that there is virtually no seasonal variation there, compared to the dance of the datapoints north of the equator, the ones south of the equator are wallflowers.
h/t to Allan Siddons
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Hug & Barrett versus IPCC
by
Heinz Hug and Jack Barrett
http://www.john-daly.com/forcing/hug-barrett.htm
The IPCC mechanism for global warming relies entirely upon the theory of radiative transfer. This assumes a long-term radiative equilibrium for the interaction between incoming solar radiation and out-going long wavelength radiation. The theory is correct for ‘blue skies’ and has to be severely modified to take into account the effects of clouds and the transfer of energy by non-radiative processes to the troposphere of latent heat of evaporation of water. In particular, the IPCC mechanism is based on the re-emission of absorbed terrestrial radiation, some of which is directed downwards and causes the extra warming of the Earth’s surface.
The mechanism of global warming must be defined in a better manner so that all relevant processes are represented.
It must be recognized that Kirchhoff’s law applies only to systems in thermal equilibrium.
The proper effects of line broadening must be recognized. That line broadening occurs at all indicates that collisional processes are important.
The value of the atmospheric sensitivity given by the IPCC seems to be too large. If the IPCC value for atmospheric sensitivity is exaggerated by a factor of about four, the predicted increase in temperature for a doubling of carbon dioxide will be too small to be discernible against the background of natural variability of the climate.
The ignoring of the spectral effects of water vapour seems to be the reason for the exaggeration of the sensitivity.
The failure of models to settle the sign of the water vapour feedback induces doubts about the whole process of modelling at the present time.
The concept of local thermodynamic equilibrium is given different interpretations and leads to errors in applications of theory to the atmospheric problem.
The kinetics of the carbon cycle needs further consideration. If the CO2 content of the atmosphere is not going to reach double that of the pre-industrial era, the whole of the IPCC approach to future climate change is in doubt.
gary gulrud (10:43:37) :
Not really Gary. The soils and their organic content are part of the terrestrial biosphere and their contributions are subject to the same analysis that applies to absolute CO2 concentrations and relative 13C:12C content in relation to the flux through the biosphere that we’ve already discussed. The bottom line is that the atmospheric 13C ratios were essentially flat in the 800-odd years before the mid 19th century and have decreased pretty faithfully as absolute atmospheric CO2 levels have risen in line with our emissions [see data in foinavon (10:07:56) and foinavon (11:50:41)].
I agree with Austin that we should address the impoverishment of agricultural soils, since the present means of industrial farming in which soils are virtually “sterilized” and then made useable by additions of large amounts of fertilizers is not sustainable in the long term. Likewise, land use changes (largely deforestation) have contributed somewhatto the enhanced CO2 concentrations.
I don’t agree with Austin that the biosphere of the Earth has been running down over time due to a decreasing rate of carbon emissions from bacteria and volcanoes. Atmospheric CO2 levels have been pretty constant (apart from reductions during ice age glacials) for the last 10 million years or so, for example, and the biosphere is rather well adapted to the extant levels of CO2 during that long period. [Apologies to Austin btw for addressing his post in the third person.]
gary gulrud (13:13:40) :
Gary, are you being seduced by the capital letters? Not even capital letters make an incorrect assertion true! We can observe from real world measurements the warming-induced enhancement of water vapour in the atmosphere, its rapid fall in response to cooling from volcanic eruptions, its temporal variation due to stochastic variations in atmospheric temperature and so on [***].
gary gulrud (13:21:22) :
I suspect you’re describing the time constant for the flux of 14C CO2 molecules through the biosphere and with the ocean surface. However if you link or cite your source we can assess this. One reason why I suspect your 14C argument is misplaced relates to the nuclear testing of the mid 20th century which significantly raised atmospheric 14CO2 levels. However these have decreased during the last half-decade or so, while absolute CO2 levels have risen. In other words we have to be careful to distinguish fluxes (within dynamic equilibria for example), and the absolute concentrations within each compartment, of the molecules of interest.
In short, CO2 levels are defined by equilibrium partitioning between atmosphere and oceans (and land somewhat), and while a significant proportion of our CO2 emissions are rapidly absorbed by the surface layers of the oceans, complete equilibration occurs on a very long time scale (many hundreds if not thousands of years). However individual molecules are in exchange with the various carbon sinks on a relatively rapid timescale. Therefore levels of identifiable trace elements (like 14C in CO2) introduced in a “pulse” (mid 20th century nuclear tests) can fall in atmospheric concentration even as Nett atmospheric CO2 concentrations rise…we can measure this easily in the real world.
Water vapour is a different kettle of fish. While the atmosphere can support essentially unlimited CO2 concentrations, water vapour has a potential atmospheric concentration that is limited by the atmospheric pressure and temperature. Both models and real world measurements [***] support the conclusion that water vapour tends to maintain, on average, a roughly constant relative humidity such that as the atmosphere warms, the absolute water vapour content rises and as the atmosphere cools, the absolute water vapour content drops. However one cannot “make the atmosphere warm” by pumping water vapour into it!
[***] e.g.
Soden BJ, et al (2005) The radiative signature of upper tropospheric moistening Science 310, 841-844
Santer BD et al. (2007) Identification of human-induced changes in atmospheric moisture content. Proc. Natl. Acad. Sci. USA 104, 15248-15253
Brogniez H and Pierrehumbert RT (2007) Intercomparison of tropical tropospheric humidity in GCMs with AMSU-B water vapor data. Geophys. Res. Lett. 34, art #L17912
Buehler SA (2008) An upper tropospheric humidity data set from operational satellite microwave data. J. Geophys. Res. 113, art #D14110
Gettelman A and Fu, Q. (2008) Observed and simulated upper-tropospheric water vapor feedback . J. Climate 21, 3282-3289
and so on. There’s lots of real world analysis of this basic point…
“”” foinavon (13:00:34) :
George E. Smith (11:59:18) :
Careful George,
Water vapour is a “permanent resident greenhouse gas” (in your parlance), but it’s levels are effectively “set” by the atmospheric temperature and pressure. We can assess this in the real world, and don’t need to pretend that it’s not true.
We can spray water (or steam if you prefer) into the atmosphere to our hearts content…it falls right back out again, because the atmosphere at whatever particular temperature and pressure can only retain so much water vapour. “””
Well foinavon whether or not water evaporates from oceans or any other water body, including the surface moisture in the soil; has absolutely nothing whatsoever to do with either the atmospheric temperature; nor with it’s pressure. It is SOLELY a function of the surface temperature OF THE WATER.
And whether it STAYS IN THE ATMOSPHERE or “falls right back out” is solely a function of the partial pressure of the water vapor in the atmosphere and the temperature (of that water vapor) in the atmosphere. The only way that air pressure and temperature and temperature affect that is that air pressure (totla) will determine the mean free path between collisions; and air temperature will determine the mean time between collisions; which together; yes will affect the temperature of the water vapor, which ultimately will try to equilibrate with the atmospheric main gases.
BUT; even after all your falling back out, and atmospheric presure and temperature limitations on water vapor content; water STILL remains in the atmosphere in quantities which swamp ALL other GHG molecules put together.
And as I explained, the thermal radiation in the long-wave IR, which lands back on the surface (to warm it) or is re-absorbed by the atmosphere in some way (to warm it), carries ZERO information as to which molecular species originally captured a solar of thermal radiation photon whose energy is ultimately transferred to the atmosphere as molecular kinetic energy.
So there is no possible way that surface evaporation processes can tell what triggered them, since the downward thermal radiation comes from the ordinary atmospheric gases, and NOT from any GHG molecule.
But hey foinavon; I’m not here to convince you; or for that matter anyone else; I don’t really care what anyone else believes. If you are happy to hang your career hat, or your scientific reputation, oin a belief that water is NOT a GHG, but a CO2 feedback mechanism; be my guest.
By the way; I’m an old (very old) Analog circuit designer, from since the days when transistors were “valves” or “vaccuum tubes” up to when they are CMOS microcircuits, in all their analog forms (try hiring any Analog IC circuit designer).
So if there is one thing that I understand right in my genes; it is FEEDBACK; and feedback always involves propagation delays; which result in phase shifts between input signals, and fed back output signals; and with any appreciable amount of phase shift, and loop gain; the whole thing will oscillate.
So perhaps you can cite for us a peer reviewed scientific climate paper in which GHG feedback oscillations were observed; even in the case of AL Gore’s 800 year feedback delay from warming to CO2 increases;
The other sort of paper that would be interesting, would be a climate model (GCM) paper; like Peter Humbug churns out with his Playstation vide game; in which the time response of his feedback circuit is modelled and described in detail; not the fictitious static model that ignores time; but the one that includes the frequency response or impulse response of the climate model.
Once again, I only need one example of each; not a whole avalanche of papers.
George
“”” Joel Shore (14:34:47) :
George E. Smith: I suggest carefully reading what other people say before going off on long tirades. I don’t disagree that water vapor is a greenhouse gas. My point (as foinavon has re-iterated in more detail) is simply that we cannot directly change its concentration … at least unless our emissions of water vapor increase by several orders of magnitude form what they are now. “””
Oh forgive me; now I get it; the reason why climatologists ignore water vapor greenhouse effect, is that they can’t hang the problem on us humans; we don’t control it, so they can’t use it to hammer us into meekly accepting their Leftist behavioral control of our lives; If man isn’t causing disastrous climate chage the greens can’t force us into accepting their utopian authoritrian future.
Which is not to say that all climatologists are leftists; just the political opportunists who sieze on their work to further their new world order.
My apologies Joel and Foinavon; so I understand that until we move to the new Hydrogen economy and get rid of the evil carbon; we will not be putting enough of man made water vapor GHG into the atmosphere to matter; got it! Hurricanes alone don’t do the job of putting enough water vapor in the atmospehre; we need our Hydrogen Humvees courtesy of Girly Man Schwarzenegger to get us to the point where water vapor becomes a proble.
George E. Smith – a short residence time does not mean that at some recent time there was no water vapour in the atmosphere. Imagine a pipe with water flowing through it. The residence time in the pipe for a given molecule of water is obviously short, but equally obviously this doesn’t mean the pipe must have been empty recently.
Scientist Tells Congress: Earth in ‘CO2 Famine’
No cause for alarm
http://epw.senate.gov/public/index.cfm?FuseAction=Minority.Blogs&ContentRecord_id=af8f5b20-802a-23ad-49fb-8a2d53f00437
“”” Ed Scott (14:47:16) :
Hug & Barrett versus IPCC
by
Heinz Hug and Jack Barrett “””
Hey Ed,
I read another paper by Heinz Hug, relating to the absorption spectrum of CO2; mainly the 15 micron band. I’m not sure I digested it properly as he came up with some exteemely small effects; but basically he made lab measurements with ain IR spectrometer.
He dsecribed his methodology, as creating a pure purely synthetic “air” sample, presumably out of N2, O2, and Ar; no idea what he did about isotopic abundances if anything; and then he carefully injected 350 something ppm of CO2 (whatever the value was when he did this some years ago, plus he added 2.6% of water vapor; and then he proceeded to scan the ir spectrum from a Globar source.
Now what I can’t figure out is why if you wanted to know the accurate experimental infrared absorption spectrum of CO2 in air at about the current abundance; would you add 2.6% of water vapoir, which can only muddy the situation since water absorbs in the same ranges as CO2 does, and more.
Why wouldn’t he use a pure dry synthetic atmosphere with no doping species besides the CO2 ?
Got any ideas ?
George
“”” Rachel (15:42:28) :
George E. Smith – a short residence time does not mean that at some recent time there was no water vapour in the atmosphere. Imagine a pipe with water flowing through it. The residence time in the pipe for a given molecule of water is obviously short, but equally obviously this doesn’t mean the pipe must have been empty recently. “””
Rachel, you are absolutely correct; but for the record, the earth emitted thermal EM radiation could care less whether the water molecule that captured one of its photons, has been in the atmosphere for a week or whether it arrived there one nanosecond ago.
Why is it that so many people today are unable to separate the significant variable in a problem from inconsequential side details that don’t relate to the problem.
What matters in evaluating the GHG absorption of earth thermal IR radiation; or for that matter incoming solar radiation, is how much GHG is in the atmosphere at the time the radiation arrives. It matters not a jot, if that GHG disappears a millisecond later to be replaced by a different GHG molecule that was in the ocen or ground before or some tree. ONLY the amount in the atmosphere at the time the radiation is there to be intercepted matters. The interception process has only one requirement; the intercepting GHG molecule, and the EM radiation photon must both be present simultaneoulsly, and the photon has to intersect the capture crossection for that absorption process, of that molecule. How long that particular molecule exists in the atmosphere after capture is totally irrelevent; so long as it perists for at least the mean time between molecular collisions so it can transfer the energy to the air molecules as kinetic energy of molecular motion.
Is this the result of the modern education “group therapy” where students “co-operate” on solving a problem so that most of them never learn the elements of problem solving, because someone in the group did it all for them, and they just wrote it up in their own words; even thought they still had no idea why it was so.
The “Residence time” that much vaunted property of CO2 that takes it 200-1000 years to vamoose; even though the natural annual cylce easily removes 18 ppm in as short as 4 months at the north pole, and 6 ppm at Mauna Loa; is a mythology to promulgate the notion that somehow CO2 that results from human activities (including exhaling) last forever and causes global warming, whereas good clean natural CO2 that escaped from the ocean or some Aspidistra, goes away in four months, but doesn’t cause global warming anyway; because it is good clean natural carbon.
If you read the report to the Congress that Dr Happer gave today, as mentioned above; you will see that he reported that we presently enjoy; or perhaps are plagued by; the lowest atmospheric CO2 levels that the earth has had in the last 600 million years; during which time life on earth flourished. Historically the levels have been upwards of 7000 ppm and it did not exterminate all life on this planet, as Hansen seems to suggest along with Al Gore, is going to happen when we hit 500 ppm.
Ain’t gonna happen; so get over it.
George E Smith:
I am not able to carry the burden of these arguments, but I can point to relevant material.
You, and perhaps others on this thread, will be interested in this article by Jeffrey A. Glassman, “On Why Co2 Is Known Not To Have Accumulated In The Atmosphere & What Is Happening With Co2 In The Modern Era,” http://www.rocketscientistsjournal.com/2007/06/on_why_co2_is_known_not_to_hav.html#more.
In this article Dr. Glassman states, inter alia, that in view of the rates of emission and absorption of atmospheric CO2 relative to the total amount of atmospheric CO2, “Regardless of which way one poses the problem, the existing CO2 in the atmosphere has a mean residence time of 1.5 years using IPCC data, 3.2 years using University of Colorado data, or 4.9 years using Texas A&M data. The half lives are 0.65 years, 1.83 years, and 3.0 years, respectively. This is not “decades to centuries” as proclaimed by the Consensus. Climate Change 2001, Technical Summary of the Working Group I Report, p. 25.”
You might also find interesting his paper “The Acquittal of Carbon Dioxide”, http://www.rocketscientistsjournal.com/2006/10/co2_acquittal.html#more. From the abstract:
“Throughout the past 420 millennia, comprising four interglacial periods, the Vostok record of atmospheric carbon dioxide concentration is imprinted with, and fully characterized by, the physics of the solubility of CO2 in water, along with the lag in the deep ocean circulation. Notwithstanding that carbon dioxide is a greenhouse gas, atmospheric carbon dioxide has neither caused nor amplified global temperature increases. Increased carbon dioxide has been an effect of global warming, not a cause. Technically, carbon dioxide is a lagging proxy for ocean temperatures. When global temperature, and along with it, ocean temperature rises, the physics of solubility causes atmospheric CO2 to increase. If increases in carbon dioxide, or any other greenhouse gas, could have in turn raised global temperatures, the positive feedback would have been catastrophic. While the conditions for such a catastrophe were present in the Vostok record from natural causes, the runaway event did not occur. Carbon dioxide does not accumulate in the atmosphere.”
Best regards,
George E. Smith says:
They don’t ignore water vapor. They just don’t see a mechanism by which water vapor concentration in the atmosphere will spontaneously change and produce dramatic climate change on its own. Do you know of such a mechanism?
The fact is that humans are dramatically changing the levels on CO2 on a timescale that is very rapid geologically speaking. It is not a “Leftist” plot to be concerned about the consequences of this. It is simply a combination of science and common sense.
Tim Clark (13:33:44) :
Hmm… I didn’t even see Steig and Mann in the references! I guess I missed that.
It is often useful to use similar procedures to simplify the underlying equations, I find this one particularly insightful when trying to explain difficult concepts:
http://rigo.altervista.org/papers/engineering_procedure.pdf
Well said Geroge, climatologists need to understand the water cycle more than the carbon cycle.
“They don’t ignore water vapor. They just don’t see a mechanism by which water vapor concentration in the atmosphere will spontaneously change and produce dramatic climate change on its own. Do you know of such a mechanism?”
Where is the evidence that CO2 is drmatically changing climate? Katrina? Australian bush fires?
George E. Smith (16:52:53) :
Why do you find dew on the grass on summer mornings?
I think that demonstrates that water vapor concentrations are a feedback to atmospheric temperatures (even though water vapor is a GHG).
WRT to your statements about the short residence times of CO2- those numbers (a few years) refer to individual CO2 molecules, not the CO2 concentrations in the atmosphere.
Fill a jar halfway up with Coke, and then seal it. Some of the CO2 in the coke will bubble up into the air above, until it reaches a certain concentration, x ppm. That concentration will be a function of the temperature and pressure. There will still be some CO2 dissolved in the Coke.
But at that concentration (x ppm), all the CO2 molecules in the air space don’t stop bouncing around and just sit in the air- some of them bounce back into solution in the Coke. But at the same time, the same number of CO2 molecules are bouncing out of the Coke and into the air space. The number of CO2 molecules moving into and out of the Coke are at equilibrium.
The lifetime of a CO2 molecule in the airspace above the Coke is finite- at some point, every CO2 molecule in the air space will bounce back into the Coke, and replaced by another bouncing out of the Coke. The average time it takes for a CO2 molecule to do that is the “lifetime” of an individual CO2 molecule.
But the CONCENTRATION of CO2 in the air space above the Coke doesn’t change. If the jar is perfectly sealed, the lifetime of x ppm in the air space is …forever.
That is why the lifetime of an individual CO2 molecule in the atmosphere tells you nothing about how long a certain concentration of CO2 remains in the atmosphere.
Sorry for the long post, but I’ve seen this point come up so many times….
Scientists might not know how water vapor can produce dramatic change, but real scientists know that there are many things they don’t know about weather and climate. Such as cloud behavior being poorly understood. Could summer thunderstorms become the dominant cloud type, with scattered towering clouds each evening which had allowed most of the surface to stay in sunlight during the day, yet collapsing in time for morning to have clear skies to warm the puddles again? No, we don’t know of any such mechanism, do we?
Back to CO2: The southern hemisphere has another mild barrier to C13 equalization with the northern hemisphere. C13 is absorbed a little more by tropic-loving C4 carbon fixation plants than by the plants using the C3 version. C3 and C4 both favor C12, but C4 a little less so.
And on the CO2 science front: “Scientist Models The Mysterious Travels Of Greenhouse Gas”
* Carbon “measurements don’t agree with current computer models of how plants and soils behave” (OK, problems with both carbon science and models.)
* “We want to know how the sources and sinks of carbon will evolve in the future, and the only way we can manage climate change is with scientific information.” (With information? It’s about time.)
* “a powerful new tool Michalak will be using—NASA’s Orbiting Carbon Observatory (OCO)” (Oh, dear. Well, that’s not going to work for a while.)
I do not call 2 ppm a year dramatic change.
I am sure that flooding of planes, either deliberate as in new rice fields, or nature induced change of a longer rain season, much more than by 2ppm the atmosphere, per day even. If there were a runaway mechanism from GHG t should run away right then and there. i.e., more heat, more water, more heat , more water,…
Who needs CO2?
I’ve pointed this out before, but another linkage between CO2 and temperature is the rate of increase in CO2. Behold:
http://www.woodfortrees.org/plot/esrl-co2/mean:12/derivative/plot/hadcrut3vgl/from:1958/scale:0.4/offset:-0.2
There must be less animals “Farting” methane in the Southern Hemisphere!
George E. Smith (16:52:53) :
George, you’re not getting the essential point about atmospheric residence times. The residence time of individual water molecules in the atmosphere is small and therefore the atmospheric water vapour concentration comes rather quickly to equilibrium defined by the local atmospheric temperature and pressure. In other words the fact that water molecules have a short residence time in the atmosphere means that the atmospheric water vapour content is locally “set” by the atmospheric temperature and pressure.
We can understand this from simple knowledge of the temperature and pressure dependence of the saturation point of air, and can measure the phenomenon in the atmosphere directly, observing the reduction in water vapour concentration as the atmosphere cools on short/medium timescales (due to volcanic eruptions/ La Nina events or even the sun setting), and its enhancement as the atmosphere warms (it turns out that so far the atmosphere tends to retain a relatively constant relative humidity on average as the atmosphere warms/cools. Again we can measure this in the real world.
The short residence time relates significantly to the response time of water vapour to changes in temperature/pressure.The latter occurs quite quickly so the water vapour concentration is near equilibrium with the temperature. That’s a fundamental difference between the water vapour and CO2. CO2 atmospheric concentrations can be varied indeendent of temperature/pressure. While atmospheric water vapour concentrations drop after volcanic eruptions (response to cooling atmosphere) CO2 levels don’t drop. While CO2 concentrations rise cumulatively as we pump the gas into the atmosphere, water vapour levels only rise in response to changes in atmospheric warming/cooling. So enhanced CO2 concentrations provides a direct additional forcing which causes atmospheric warming. Water vapour levels rise in response to the warming as a feedback, providing an amplification of the primary warming.
Climatologists don’t “ignore water vapor greenhouse effect”…they just address the phenomenon correctly in line with our understanding and real world evidence. It’s science George…not undergraduate style politics about “Leftist behavioral control”!
Anybody have a ref. for the little-known-because-punctures-paradigms paper showing there is a measurable increase of CO2 from the regular influx of mini-comets? With natural carbon sequestration that we cannot avoid, like peat>coal and shells>chalk, I think we need all the CO2 we can get. For the sake of the science, I’d like the source. When I saw it it seemed well-done.
I notice the overall d13C whatsit goes down from about -7.8 to about -8.4 over 10 years. Far bigger annual fluctuations are likely due BOTH to summer vegetation depleting the 12C levels and raising the 13C proportion, AND to winter fossil fuels higher use lowering the 13C proportion – so we cannot measure either factor absolutely. But the overall 13C lowering – what does that portend?
I think the geologist Prof Segalstad has some answers in this summary of his 2008 paper
Carbon isotope mass balance modelling of atmospheric vs. oceanic CO2
Stable 13C/12C isotope ratios, expressed as δ13C in permil vs. PDB, give us the only way to unequivocally determine the fraction of anthropogenic CO2 in the atmosphere. The natural atmospheric CO2 reservoir has δ13C -7 when in isotopic equilibrium with marine HCO3- and CaCO3. CO2 from burning of fossil-fuel and biogenic materials has δ13C -26. A pre-industrial CO2 value of 280 ppmv in air was assumed by IPCC based on selected low value CO2 data from ice cores (omitting measured high values up to 7,400 ppmv), matched with contemporary measurements by transposition of data with different ages (Jaworowski et al. 1992). IPCC claims that the rise in CO2 to 353 ppmv in 1990 and 379 ppm in 2005 is only due to anthropogenic CO2 (IPCC 1990, 2007).
δ13C reported for atmospheric CO2 was -7.489 in Dec. 1978, decreasing to -7.807 in Dec. 1988 (Keeling et al. 1989). If the decreasing δ13C was only caused by mixing natural CO2 with CO2 from burning of fossil fuels or plants (79%/21% CO2 mix; lifetime 50-200 years; IPCC 1989), the current atmospheric CO2 δ13C should be -11, much lower than reported. The December 1988 atmospheric CO2 composition was computed for its 748 GT C (GT = 1015 g) total mass and δ13C = -7.807 for 3 components: (1) natural fraction remaining from the pre-industrial atmosphere; (2) cumulative fraction remaining from all annual fossil-fuel CO2 emissions; (3) carbon isotope mass-balanced natural fraction. The masses of component (1) and (2) were computed for different atmospheric lifetimes of CO2.
The result fits a lifetime of 5 years, in agreement with 14C studies. The mass of all past fossil-fuel and biogenic emissions remaining in the current atmosphere was 30 GT C or less, i.e. maximum 4%, corresponding to an atmospheric concentration of 14 ppmv. The implication of the 5 year lifetime is that 135 GT C (18%) of the atmospheric CO2 is dynamically exchanged each year.
Partitioning of CO2 between atmosphere and hydrosphere is governed by Henry’s Law, implying that 50-60 times more CO2 is dissolved in the oceans than in the atmosphere. Due to the retrograde solubility of CO2 in water, less CO2 will be dissolved in water at higher temperatures.
At least 96% of the current atmospheric CO2 comes from non-fossil-fuel sources, i.e. natural marine and juvenile sources. Hence for the atmospheric CO2 budget marine degassing and juvenile degassing from e.g. volcanic sources must be much more important, and burning of fossil-fuel and biogenic materials much less important, than hitherto assumed.
Thermochemical modelling of calcium carbonate in seawater shows that pH would have to be decreased by 2 units, and H+ activity increased by 100, for Ca carbonate to dissolve at 25°C. By increasing atmospheric CO2 this would by itself require 100 times the present CO2 level. However, mineral buffers in the sea constitute an infinite buffer capacity (Stumm & Morgan 1970), making carbonate destructive ocean acidification from anthropogenic CO2 impossible.
Lucy Skywalker (07:00:25)
Your link doesn’t work. Can you check it?
Otherwise there doesn’t seem to be any paper published by a Dr. Segalstad with a 2008 date. In fact the most recent paper published by a likely Segalstad (TV Segalstad – is that him?) seems to have been 1992…
“I think the geologist Prof Segalstad has some answers”
Good, fuel and a fan for the flames.
foinavon:
de Jager, Usoskin 2006. Knock yourself out.
Lucy Skywalker (07:00:25) :
Dear Lucy,
Segalstad is – again – confusing between what is still in the atmosphere as individual molecules from human origin (about 6% nowadays) and the cause of the increase of the total mass of CO2 in the atmosphere, which is almost entirely from human origin. But even if the emissions are twice as high as what is seen as increase in the atmosphere (which excludes nature as source, it is a sink), the year by year seasonal exchange as given by Segalstad replace about 20% of all CO2, including human CO2 with (deep) ocean CO2, but that says nothing about how much excess CO2 is released or absorbed as total (as nicely described by Chris V.).
Thus the seasonal movements reduces the % of human CO2 in the atmosphere in ratio with the exchange rate and the mass of CO2 in the atmosphere (150 GtC / 800 GtC), while the sink rate is currently only 4 GtC on a total of 800 GtC. If we should stop the emissions today, the CO2 levels in the atmosphere would drop with 2 ppmv, the year after with 1.5 ppmv,… Thus with much longer half life times than 5 years to go back to pre-industrial levels.
So, while the reasoning of Segalstad is perfectly valid for how much CO2 of human origin still is in the atmosphere, that doesn’t give any indication how long the excess mass of CO2 will remain in the atmosphere, as that is completely independent of the molecular exchange rate.
Here a graph which shows what happens in the atmosphere and upper oceans if you add 100 GtC CO2 (about 50 ppmv) at once and let nature do the rest:
http://www.ferdinand-engelbeen.be/klimaat/klim_img/fract_level_pulse.jpg
where FA and FL are the fractions of human CO2 in air and upper oceans, FA/FL their ratio, tCA total carbon in the atmosphere and nCA total natural carbon in the atmosphere (human CO2 is the difference), all based on realistic exchange rates.