UPDATED – see below
Monckton provides these slides for discussion along with commentary related to his recent post on CO2 residence time – Anthony
There is about one molecule of 13C in every 100 molecules of CO2, the great majority being 12C. As CO2 concentration increases, the fraction of 13C in the atmosphere decreases – the alleged smoking gun, fingerprint or signature of anthropogenic emission: for the CO2 added by anthropogenic emissions is leaner in 13C than the atmosphere.
However, anthropogenic CO2 emissions of order 5 Gte yr–1 are two orders of magnitude smaller than natural sources and sinks of order 150 5 Gte yr–1. If some of the natural sources are also leaner in CO2 than the atmosphere, as many are, all bets are off. The decline in atmospheric CO2 may not be of anthropogenic origin after all. In truth, only one component in the CO2 budget is known with any certainty: human emission.
If the natural sources and sinks that represent 96% of the annual CO2 budget change, we do not have the observational capacity to know. However, we do not care, because what is relevant is net emission from all sources and sinks, natural as well as anthropogenic. Net emission is the sum of all sources of CO2 over a given period minus the sum of all CO2 sinks over that period, and is proportional to the growth rate in atmospheric CO2 over the period. The net emission rate controls how quickly global CO2 concentration increases.
CO2 is emitted and absorbed at the surface. In the atmosphere it is inert. It is thus well mixed, but recent observations have shown small variations in concentration, greatest in the unindustrial tropics. Since the variations in CO2 concentration are small, a record from any station will be a good guide to global CO2 concentration. The longest record is from Mauna Loa, dating back to March 1958.
The annual net emission or CO2 increment, a small residual between emissions and absorptions from all sources which averages 1.5 µatm, varies with emission and absorption, sometimes rising >100% against the mean trend, sometimes falling close to zero. Variation in human emission, at only 1 or 2% a year, is thus uncorrelated with changes in net emission, which are independent of it.
Though anthropogenic emissions increase monotonically, natural variations caused by Pinatubo (cooling) and the great el Niño (warming) are visibly stochastic. Annual changes in net CO2 emission (green, above) track surface conditions (blue: temperature and soil moisture together) with a correlation of 0.93 (0.8 for temperature alone), but surface conditions are anti-correlated with δ13C (red: below).
The circulation-dependent naturally-caused component in atmospheric CO2 concentration (blue above), derived solely from temperature and soil moisture changes, coincides with the total CO2 concentration (green). Also, the naturally-caused component in δ13C coincides with observed δ13C (below).
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ADDED (the original MS-Word document sent by Monckton was truncated)
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The naturally-caused component in CO2 (above: satellite temperature record in blue, CRU surface record in gray), here dependent solely on temperature, tracks not only measured but also ice-proxy concentration, though there is a ~10 µatm discrepancy in the ice-proxy era. In the models, projected temperature change (below: blue) responds near-linearly to CO2 concentration change (green).
In the real world, however, there is a poor correlation between stochastically-varying temperature change (above: blue) and monotonically-increasing CO2 concentration change (green). However, the CO2 concentration response to the time-integral of temperature (below: blue dotted line) very closely tracks the measured changes in CO2 concentration, suggesting the possibility that the former may cause the latter.
Summary
Man’s CO2 emissions are two orders of magnitude less than the natural sources and sinks of CO2. Our emissions are not the main driver of temperature change. It is the other way about.
Professor Salby’s opponents say net annual CO2 growth now at ~2 μatm yr–1 is about half of manmade emissions that should have added 4 μatm yr–1 to the air, so that natural sinks must be outweighing natural sources at present, albeit only by 2 μatm yr–1, or little more than 1% of the 150 μatm yr–1 natural CO2 exchanges in the system.
However, Fourier analysis over all sufficiently data-resolved timescales ≥2 years shows that the large variability in the annual net CO2 emission from all sources is heavily dependent upon the time-integral of absolute global mean surface temperature. CO2 concentration change is largely a consequence, not a cause, of natural temperature change.
The sharp Pinatubo-driven cooling of 1991-2 and the sharp Great-el-Nino-driven warming of 1997-8, just six years later, demonstrate the large temperature-dependence of the highly-variable annual increments in CO2 concentration. This stochastic variability is uncorrelated with the near-monotonic increase in anthropogenic CO2 emissions. Absence of correlation necessarily implies absence of causation.
Though correlation between anthropogenic emissions and annual variability in net emissions from all sources is poor, there is a close and inferentially causative correlation between variable surface conditions (chiefly temperature, with a small contribution from soil moisture) and variability in net annual CO2 emission.
Given the substantial variability of net emission and of surface temperature, the small fraction of total annual CO2 exchanges represented by that net emission, and the demonstration that on all relevant timescales the time-integral of temperature change determines CO2 concentration change to a high correlation, a continuing stasis or even a naturally-occurring fall in global mean surface temperature may yet cause net emission to be replaced by net uptake, so that CO2 concentration could cease to increase and might even decline notwithstanding our continuing emissions.
Natural temperature change and variability in soil moisture, not anthropogenic emission, is the chief driver of changes in CO2 concentration. These changes may act as a feedback contributing some warming but are not its principal cause.
We need a source of C12 large enough to swamp the C12 emitted by our fossil fuel emissions thereby causing a decline in the proportion of C13 without our involvement.
This is interesting:
“Where cold waters well up from the depths (such as in the North Atlantic), the water carries 12C back up with it”
from here:
http://en.wikipedia.org/wiki/Isotopes_of_carbon
It has previously been proposed that the current rise in atmospheric CO2 might be linked to returning CO2 rich waters from the thermohaline circulation hence the time lag of 800 years or so between temperature changes and the atmospheric response.
Could such returning C12 rich water be affecting the atmospheric isotope ratio ?
eric1sceptic said:
” What makes more sense in that case is that there is net in-gassing mostly independent of short term temperature changes but very slightly modulated by the temperature.”
For a stable system that would make sense because ocean life forms constantly sequester carbon to the ocean floor in their skeletons.
However one should consider internal ocean behaviour modulated by temperature variations (probably solar induced) on that 800 year time lag.
The ocean cycles would thus vary either side of equilibrium sometimes net absorbing and sometimes net releasing and in periods of net release it appears that the excess would be C12 rich due to more cold water upwelling from the depths.
William Astley says:
November 26, 2013 at 4:16 pm
I had read the Humlum paper when it was published and several reaction on it thereafter, but couldn’t remember where I had seen the most important rebuttal.
Anyway, from memory: by taking the DIFF12, Humlum e.a. effectively remove the long term trend from the graph and only look at the short term variations.
It is the same for Bart, Salby and Humlum: they project the fast variations, where everybody agrees (warmists as well as skeptics) that they are caused by fast temperature variations to the longer term trend. But the fast variations and the long term trends come from different near independent processes, no matter if the second process is temperature related of human emissions related.
Their conclusions therefore are not based on observations, which in fact contradict them:
Our previous analyzes suggest that such other more important effects are related to temperature, and with ocean surface temperature near or south of the Equator pointing itself out as being of special importance for changes in the global amount of atmospheric CO2
Well, have a look at the difference in timing of the increase of CO2 in the atmosphere:
http://www.ferdinand-engelbeen.be/klimaat/klim_img/co2_trends_1995_2004.jpg
There is a lag of 6 months to 2 years between SH CO2 levels and NH CO2 levels, which points to a CO2 source in the NH, not in de SH.
Which effectively shows that the conclusion of Humlum e.a. about the origin of the increase of CO2 in the atmosphere is wrong.
there is a significant source of low C13, CO2 in the deep ocean – it appears based on other analysis that the source of the CO2 is primordial CH4 which is very low in C13 that is then converted to CO2 by micro bacterial action.
That is possible, but until now that has no measurable influence of the δ13C level of the deep oceans, which still is around zero per mil. When that water comes near the surface it brings lots of nutritients from the deep with it, increasing plankton growth and all subsequent biolife. The net result: a firm increase of δ13C(+1 to +5 per mil) in the ocean surface at the upwelling places and an increase of δ13C in the atmosphere (at -8 per mil) if CO2 from that source is released.
“The net result: a firm increase of δ13C(+1 to +5 per mil) in the ocean surface at the upwelling places and an increase of δ13C in the atmosphere (at -8 per mil) if CO2 from that source is released.”
Is there evidence in support of that ?
The creation of more C13 by biological activity near the surface might offset some of the effect of upwelling C12 rich water but does it negate it completely ?
My link also says:
“when the plankton dies, it sinks and takes away 12C from the surface, leaving the surface layers relatively rich in 13C.”
That might not happen if the 12C taken away from the surface is constantly replaced by even more C12 coming up. That C12 flooding up could leave the emissions to the atmosphere less rich in C13 than the average atmospheric level.
A great deal could be explained if the upwelling C12 rich water does overwhelm the biological response. There are other factors that determine how much biological activity can occur.
Greg Goodman says:
November 26, 2013 at 10:59 pm
Thanks , that graph is interesting. it shows that the deviation does indeed seem related to temperature. Could you explain exactly what your “emm-f(dpCO2)” means?
emissions minus the decay function of CO2 which is
k*(Cobs – Ceq)
where k = 4.5/230 GtC/yr/GtC
and Ceq = 290 ppmv (1870) + k2*(T – T1870)
where k2 = 8 ppmv/K
This sort of think could be explained by a number of factors (increase of energy going into air-con installations, changes in out-gassing, greater deviation of atm CO2 from equilibrium ) but it’s interesting to look at.
The emissions can explain the trend, while the short term temperature (and moisture) variation does explain the short term variation in the CO2 rate of change.
The rather fixed ratio between emissions and increase in the atmosphere is more coincidental and probably caused by the slightly quadratic increase of human emissions. With fixed emissions, the increase in the atmosphere would go assymptotically to a new equilibrium…
stephen wilde says:
November 27, 2013 at 2:36 am
Is there evidence in support of that ?
http://en.wikipedia.org/wiki/Upwelling
look for “High productivity”
That might not happen if the 12C taken away from the surface is constantly replaced by even more C12 coming up.
The deep oceans at zero δ13C still are richer in 13C then the 13C level in the atmosphere, but poorer that the surface waters. Thus even if more CO2 is released directly from the deep oceans, that would slightly increase the δ13C level of the atmosphere, be it borderline.
Nevertheless, the decline of δ13C in the atmosphere is so strong that there is no way that the oceans can have caused that, to the contrary: the higher δ13C from the CO2 circulation through the atmosphere reduced the δ13C decline in the atmosphere to 1/3rd of what can be expected from human emissions:
http://www.ferdinand-engelbeen.be/klimaat/klim_img/deep_ocean_air_zero.jpg
William Astley says: November 26, 2013 at 1:47 pm
“if the Bern model was correct, atmospheric C14 would have decline to a plateau as it reaches equilibrium with the smaller carbon reservoirs (land and surface ocean). That is not what is observed. The C14 drops to very low levels as it is mixing with the deep ocean reservoir.
http://www.false-alarm.net/wp-content/uploads/2013/06/paper1.pdf“
The paper you link to is no longer there. But I remember it from the time of Prof P’s original post. It was wrong, because it dealt with a Δ expressed in terms of the ratio of C14 to C. But we have been putting very large amounts of CO2 in the air from fossil fuels which has no C14. Δ would by now be substantially negative, relative to 1950, because of this dilution. So “low levels” are not surprising.
Ferdi: emissions minus the decay function of CO2 which is
k*(Cobs – Ceq)
where k = 4.5/230 GtC/yr/GtC
===
Thanks. So that brings us back to the question of the 51 year time const that you have so far ignored on several requests:
how do you derive k = 4.5/230 ; (and hence tau=230/4.5=51)
Phil Wrote:
“I think that you must have done the calculations incorrectly then, because Ferdinand’s value is consistent with all the values I’ve seen published. Try using this on-line calculator, you’ll see much lower sensitivity than you’re suggesting”.
The calculation, as I said above, is exceptionally straightforward, and I re-calculated it, and, got the same result: a change of 1°C alters CO2’s solubility by 3%, the result is also supported by graphs that have been posted, funnily enough, on this very site, see here: http://wattsupwiththat.com/2010/06/09/a-study-the-temperature-rise-has-caused-the-co2-increase-not-the-other-way-around/ and here: http://wattsupwiththat.com/2009/02/20/basic-geology-part-2-co2-in-the-atmosphere-and-ocean/ Try it yourself using the van’t Hoff temperature equation on Wikipedia’s Henry’s law page, and tell me what result you get. Also, you say that Ferdinand’s value is ‘consistent’ with the papers you have seen published. Would you mind citing these papers and perhaps pulling a few quotes out? Also, were those calculations of the entire ocean or just the surface layer? Anyway, the working out for my calculation can be seen on my blog here if you’re interested: http://chipstero7.blogspot.co.uk/2013/11/it-is-often-asserted-by-cagw-advocates.html
Just to point something out, the WattsUpWithThat article I cited above estimates a change in CO2’s solubility of 4% from a 1°C change which the article claims would “roughly triple the CO2 concentration in the atmosphere”, whereas I calculated independently a 3% change using the equation on Wikipedia. I decided to stick with the conservative estimate of 3%.
Richard says:
November 27, 2013 at 5:26 am
Phil Wrote:
“I think that you must have done the calculations incorrectly then, because Ferdinand’s value is consistent with all the values I’ve seen published. Try using this on-line calculator, you’ll see much lower sensitivity than you’re suggesting”.
The calculation, as I said above, is exceptionally straightforward, and I re-calculated it, and, got the same result: a change of 1°C alters CO2’s solubility by 3%, the result is also supported by graphs that have been posted, funnily enough, on this very site, see here: http://wattsupwiththat.com/2010/06/09/a-study-the-temperature-rise-has-caused-the-co2-increase-not-the-other-way-around/ and here: http://wattsupwiththat.com/2009/02/20/basic-geology-part-2-co2-in-the-atmosphere-and-ocean/ Try it yourself using the van’t Hoff temperature equation on Wikipedia’s Henry’s law page, and tell me what result you get.
The problem is is that the calculation is not ‘exceptionally straightforward’, Henry’s Law can not be applied the simple way you do for a gas which reacts with the solvent, which is the case with CO2 (see any Physical chemistry text). Consequently you have to allow for the shift in the chemical equilibria involved, this is what the Revelle factor does.
Checkout the web calculator I suggested, notice the effect of pH.
http://www.microcosmofscience.com/CO2%20and%20TIC%20calculator.html#pco2uatm
That’s rather vague Phil. The calculation to determine changes in CO2’s solubility due to temperature changes is indeed straightfoward and the graphs I have referenced from this site support my result. Also changes in pH will not change CO2’s solubility as you appear to be thinking it does, it merely changes the ratio of all species of CO2 expressed as DIC. Furthermore I have no idea what you mean when you say “Henry’s law cannot be applied” since I wasn’t even applying Henry’s law when I calculated the change in CO2’s solubility. Also what do you mean when you say “you have to allow for the shift in chemical equilbria involved” and “this is what the Revelle Factor does”. Could you elaborate here? If you don’t trust my calculations or can’t verify it independently for yourself my advice would be to take a look at that Watts-Up-With-That article I cited showing that a change of 1C in ocean temperature would be sufficient by itself to “roughly triple the CO2 concentration in the atmosphere”.
Greg Goodman says:
November 27, 2013 at 3:51 am
I thought that I had explained that on November 25, 2013 at 12:51 pm, or do you mean the figures themselves?
The current increase in the atmosphere is ~110 ppmv (=230 GtC) above equilibrium. The current sink rate (emissions – increase in the atmosphere) is ~2.15 ppmv/yr (= 4.5 GtC/yr), which gives an excess e-fold decay rate of 110/2.15 or 230/2.5 or slightly over 50 years.
Richard says:
November 27, 2013 at 9:36 am
That’s rather vague Phil. The calculation to determine changes in CO2′s solubility due to temperature changes is indeed straightfoward and the graphs I have referenced from this site support my result. Also changes in pH will not change CO2′s solubility as you appear to be thinking it does, it merely changes the ratio of all species of CO2 expressed as DIC. Furthermore I have no idea what you mean when you say “Henry’s law cannot be applied” since I wasn’t even applying Henry’s law when I calculated the change in CO2′s solubility.
That’s strange because you said that you used the Van’t Hoff isochore to calculate the dependence of the Henry’s Law coefficient which you then used to calculate the new solubility!
Richard says:
November 27, 2013 at 5:26 am
Sorry Richard, seems that I have missed your first message…
The calculation, as I said above, is exceptionally straightforward, and I re-calculated it, and, got the same result: a change of 1°C alters CO2’s solubility by 3%
If we may assume that the 3% is the same for seawater as for fresh water (which is not the case, seawater can absorb about 10 times more CO2 – that is what the Revelle factor says), that means that the pCO2 of seawater increased with several %. Let us assume 3% (see further for the exact calculation).
Then per Henry’s law, to bring seawater back into equilibrium with the atmosphere, the atmospheric pressure need to increase with 3% and everything is back into equilibrium. 3% of the atmospheric pressure is ~10 ppmv. A little at the low side, but the 3% increase in pCO2 of seawater is not that exact.
I have looked at your web page, but what you wrote is not exactly right: the mass difference of carbon in the atmosphere vs. oceans indeed is 1:50, but mass doesn’t play any role here. Henry’s law is about pressure differences, not about mass differences.
To give an example: if you shake a bottle of coke of 0.5 or 1.o or 1.5 l, filled from the same batch, you will find (nearly) the same pressure under the screw cap at the same temperature…
Now the exact calculation:
From http://www.ldeo.columbia.edu/res/pi/CO2/carbondioxide/text/LMG06_8_data_report.doc
For regular seaship cruises, the pCO2 measurements at the instrument are corrected towards the real (in situ) seawater temperature with following formula:
(pCO2)sw @ur momisugly Tin situ = (pCO2)sw @ur momisugly Teq x EXP[0.0423 x (Tin-situ – Teq)]
for a seawater pCO2 value of 400 μatm, an increase of 1 K temperature will give 417 μatm or an increase of 17 μatm. That will give an increase in inflow in the atmosphere from the oceans (and decrease in outflow), until the atmosphere also increased with 17 μatm:
http://www.ferdinand-engelbeen.be/klimaat/klim_img/upwelling_temp.jpg
Phil. says: November 27, 2013 at 7:44 am
“Checkout the web calculator I suggested, notice the effect of pH.”
I have a more graphical version here.
Ferdinand at 2:41am
“The rather fixed ratio between emissions and increase in the atmosphere is more coincidental and probably caused by the slightly quadratic increase of human emissions. ”
I would have said that the roughly constant ratio of about 0.5 is due to having two large reservoirs, the atmosphere and the rest of the biosphere, which interchange CO2 at a large rate. If you add a comparatively small amount of CO2 to one reservoir, then you will end up with half of the increase in each, provided the rate of transfer between reservoirs is greater than the rate at which something is added to one.
“I have looked at your web page, but what you wrote is not exactly right: the mass difference of carbon in the atmosphere vs. oceans indeed is 1:50, but mass doesn’t play any role here. Henry’s law is about pressure differences, not about mass differences”.
But the partitioning ratio for CO2 between the atmosphere and oceans is around 1:50 at the average surface temperature of 15°C, and as far as I understand, this is why there exists significantly more CO2 in the oceans, approximately 50 times, than the atmosphere. This partitioning ratio is governed by pressure differences, as you say, not mass, but the mass of CO2 in the oceans is still 50 times that of the atmosphere per meter squared. This implies that only about 2% of human CO2 emissions can stay in the atmosphere to be added to the CO2 greenhouse while the other 98% must be absorbed into the oceans. The arithmetic is straightforward and Henry’s law has been around since the end of the 19th century so I am a bit surprised that the climate science community seems to be largely unaware of it. Well, not all the scientific community. Prof Tom Segalstad has some good papers on Henry’s law that I would recommend you checking out. I dare say, you already have.
“For a seawater pCO2 value of 400 μatm, an increase of 1 K temperature will give 417 μatm or an increase of 17 μatm. That will give an increase in inflow in the atmosphere from the oceans (and decrease in outflow), until the atmosphere also increased with 17 μatm”.
I remember reading an article by Ed Caryl a few months ago on this very subject and him reaching a similar conclusion to me and you swiftly rebutting the article in question by saying the same thing you have told me, i.e. that Henry’s law implies an increase in atmospheric CO2 of 16ppmv in response to a 1°C change. However it’s not immediately obvious how you reached that conclusion. Would you mind showing your working out? You know, some good old-fashioned math? You see, the calculation I performed on my blog was to see how much a given temperature change would alter CO2’s solubility coefficient using the aforementioned van’t Hoff and then to calculate the subsequent change in CO2’s aqueous concentration using Henry’s law. The result I got from a 0.272°C change was a decrease from 1.259×10^5mol/L to 1.249×10^-5 mol/L. I still see no apparent problem with that calculation so far. But we’ve been here before Ferdinand, many times, when we discussed the validity of the ice-core data on Joanne Nova’s blog and the inapplicability of the Revelle Factor.
Richard says:
November 28, 2013 at 7:39 am
Let us start with the mass difference:
The ocean contains some 40,000 GtC
The atmosphere contains some 800 GtC
or a ratio of 50:1
The exchange between deep oceans and atmosphere is quite slow (estimated at ~40 GtC/year in and out), but (near) unlimited in capacity. Thus the human emissions indeed will disappear in the deep oceans sooner or later and leaving an increase of ~1% in deep oceans and atmosphere when everything is in equilibrium. The estimated e-fold time is ~50 years, the half life time under 40 years.
The exchange of CO2 between deep oceans and atmosphere simply goes in and out. As long as there is no difference between the influxes and outfluxes, there is not the slightest change in CO2 of the atmosphere or the oceans.
Thus what happens if there is a gobal increase in ocean temperature?
– first the pCO2 of the ocean water increases with 17 μatm for the same CO2 concentration at the upwelling and downwelling places.
– the increase in pCO2 at the upwelling places increases the influx of the atmosphere with about 5% (as the difference in pCO2 between upwelling waters and atmosphere increases with ~5%).
– the increase in pCO2 at the upwelling places decreases the outflux from the atmosphere with about 5% (as the difference in pCO2 between upwelling waters and atmosphere decreases with ~5%).
– both the increase in influx and the decrease of outfluxgives an imbalance between inputs and outputs and thus increase the CO2 level (~pCO2) of the atmosphere.
– an increase of pCO2 in the atmosphere reduces the inflow from the oceans and increase the outflow into the oceans, thus effectively re-establishing the equilibrium in in/out fluxes, but at a higher pCO2 in the atmosphere.
– the new equilibrium is reached if the pCO2 of the atmosphere is increased with 17 μatm.
– the total amount of CO2 needed to increase the pCO2 in the atmosphere is about 37 GtC.
Here the graph of what happened with fluxes and CO2 levels in the atmosphere after a sudden temperature rise of 1K:
http://www.ferdinand-engelbeen.be/klimaat/klim_img/upwelling_temp.jpg
Thus for 1 K increase in temperature, the deep oceans need to deliver 37 GtC to the atmosphere. or 0.1% of its carbon content. That is all. And everything is back in equilibrium…
Ferdinand Engelbeen says:
November 28, 2013 at 10:46 am
Maybe I need to clarify the calculation a little further:
The pCO2 at the upwelling places can reach 750 μatm at the upwelling places. That gives about 40 GtC/yr inflow in the atmosphere with a pressure difference of 750 – 400 μatm.
If the temperature increases with 1 K, the pCO2 of the oceans gets 767 μatm and the influx increases with:
40 GtC/yr * 367/350 = 41.9 GtC/yr or about +5%
The reverse happens at the sink side. But when the pCO2 in the atmosphere increases, the differences go back to the old values…
The result I got from a 0.272°C change was a decrease from 1.259×10^5mol/L to 1.249×10^-5 mol/L.
That is right and shows what happens at the surface of the upwelling places. That is what increases the influx from the oceans in the atmosphere. But that is reversed when the pressure in the atmosphere is increasing. A higher pressure in the atmosphere does push more CO2 into the ocean surface (or gives less release).
Think again at the three different sized Coke bottles: once the equilibrium pressure is reached (for changes in temperature), no more CO2 is going from the liquid into the atmosphere above it, no matter how much difference of mass there is in the liquid.
Richard says:
November 27, 2013 at 9:36 am
That’s rather vague Phil. The calculation to determine changes in CO2′s solubility due to temperature changes is indeed straightfoward and the graphs I have referenced from this site support my result. Also changes in pH will not change CO2′s solubility as you appear to be thinking it does, it merely changes the ratio of all species of CO2 expressed as DIC.
Not true, you’re not doing the calculations correctly for seawater!
E.g. “If the surface ocean PCO concentrations continue to increase in proportion with the atmospheric CO increase, a doubling of atmospheric CO from preindustrial levels will result in a 30% decrease in carbonate ion concentration and a 60% increase in hydrogen ion concentration. As the carbonate ion concentration decreases, the Revelle factor increases and the ocean’s ability to absorb more CO from the atmosphere is diminished. The impact of this acidification can already be observed today and could have ramifications for the biological feedbacks in the future [Feely et al., 2004].”
http://www.pmel.noaa.gov/pubs/outstand/sabi2683/sabi2683.shtml
Also using: http://www.microcosmofscience.com/CO2%20and%20TIC%20calculator.html#pco2uatm
Seawater, pH 8.05, temperature 16ºC, salinity 35 ppK, total alkalinity 2.4 mmole/L has an equilibrium pCO2 of 390.73 µatm and TIC of 2.1415 mole/L
reduce the pH to 8.00 and you get pCO2 of 447.78 µatm and TIC of 2.1683 mole/L
Furthermore I have no idea what you mean when you say “Henry’s law cannot be applied” since I wasn’t even applying Henry’s law when I calculated the change in CO2′s solubility.
In your latest post you contradicted this: “You see, the calculation I performed on my blog was to see how much a given temperature change would alter CO2’s solubility coefficient using the aforementioned van’t Hoff and then to calculate the subsequent change in CO2’s aqueous concentration using Henry’s law.”
Also what do you mean when you say “you have to allow for the shift in chemical equilbria involved” and “this is what the Revelle Factor does”. Could you elaborate here?
“We derive explicit expressions of the Revelle factor and several other buffer factors of interest to climate change scientists and those studying ocean acidification. These buffer factors quantify the sensitivity of CO2 and H+ concentrations ([CO2] and [H+]) and CaCO3 saturation (Ω) to changes in dissolved inorganic carbon concentration (DIC) and alkalinity (Alk). The explicit expressions of these buffer factors provide a convenient means to compare the degree of buffering of [CO2], [H+], and Ω in different regions of the oceans and at different times in the future and to gain insight into the buffering mechanisms.”
http://onlinelibrary.wiley.com/doi/10.1029/2008GB003407/abstract
Your statement: “The arithmetic is straightforward and Henry’s law has been around since the end of the 19th century so I am a bit surprised that the climate science community seems to be largely unaware of it. “
is frankly nonsense since Henry’s Law is well known in the field and is correctly applied along with the associated chemical equilibria as the referenced papers show.
Richard says:
November 27, 2013 at 9:36 am
Also what do you mean when you say “you have to allow for the shift in chemical equilbria involved” and “this is what the Revelle Factor does”. Could you elaborate here?
Here’s a reference to a more detailed explanation and derivation of the Revelle Factor etc. It even explains the reaction kinetic equations in case you’re not familiar with them (section 2.2.x).
http://www.eng.warwick.ac.uk/staff/gpk/Teaching-undergrad/es427/Exam%200405%20Revision/Ocean-chemistry.pdf
E.g. “The carbonate system in seawater comprises only a few components, essentially CO2, HCO3−, CO3–, H+, OH−, and may be described by equations derived from the law of mass action. Its behaviour in response to perturbations is not always easy to predict by intuitive reasoning:
• A doubling of CO2 concentration in the atmosphere will not cause a dou-bling of the total dissolved inorganic carbon, DIC, at equilibrium. Instead it results in an increase of only ∼10%. This low increase is due to the dissociation of CO2 and the simultaneous change of pH (see discussion of the Revelle factor).”
Emphasis mine.
“If the surface ocean PCO2 concentrations continue to increase in proportion with the atmospheric CO2 increase, a doubling of atmospheric CO2 from preindustrial levels will result in a 30% decrease in carbonate ion concentration and a 60% increase in hydrogen ion concentration. As the carbonate ion concentration decreases, the Revelle factor increases and the ocean’s ability to absorb more CO2 from the atmosphere is diminished. The impact of this acidification can already be observed today and could have ramifications for the biological feedbacks in the future”.
I think Tom Segalstad may already have defused this possible riposte with his erudite discussion of the IPCC’s ‘Revelle factor’ which enshrines this principle. As I have argued on my blog too it doesn’t really make sense. In any case the Revelle Factor is a measure of the oceans capacity to absorb anthropogenic CO2 due to various dissociation constants changing the ratio of DIC as pH decreases and has nothing to do with CO2’s solubility as a direct result of a given temperature increase as my calculation covers. My calculation is just a measure of the decrease in CO2’s solubility due to a temperature change. That is all. Therefore the Revelle Factor, be it even correct, is irrelevant here. Also, pH doesn’t change CO2’s solubility in water either, it just alters the ratio of DIC. It may decrease H2CO3 relative to HCO3 and CO32, but it won’t change the actual amount of total DIC dissolved in water. Take a soda drink as an example. There exists the same – about 50 times the concentration – in the water of a soda drink at very low pH compared to the trapped air under the bottle-cap than there exists in the ocean relative to the atmosphere. The partitioning ratios are the same and yet the pH is greatly different. The principal environmental parameter that changes CO2’s solubility and hence its partitioning ratio, as far as I am aware, is temperature, and to a lesser extent, salinity.
I think one main weakness of the Revelle Factor argument, if it were even correct to begin with, is that it would have to be transitory and would disappear permanently when equilibrium was reached. When equilibrium between DIC and atmospheric CO2 is reached, the concentration of CO2 in the oceans must be some 50 times greater than the atmosphere as determined by Henry’s law in accordance with standard physical chemistry. In the case of CO2 entering and outgassing from the oceans, the rate at which this can happen is surprisingly fast, depending on relative partial pressures of CO2 in atmosphere and oceans respectively of course. Bert Bolin 1982 for example has estimated an equilibrium time of only ¾’s of a year and Tom Segalstad estimates an equilibrium time between DIC and atmospheric CO2 at slightly over a year. This would imply that about 98% of human CO2 (in accordance with the 1:50 partitioning ratio at a temperature of 288K) would get absorbed ‘permanently’ annually, thereby discounting humans as a significant contributor to the atmospheric CO2-greenhouse. Toms Segalstad explains the significance of Henry’s law and why the Revelle Factor is ‘ideologically defined’ in his 1998 paper “Carbon cycle modelling and the residence time of natural and anthropogenic atmospheric CO2: on the construction of the Greenhouse Effect Global Warming dogma”.
“That is right and shows what happens at the surface of the upwelling places. That is what increases the influx from the oceans in the atmosphere. But that is reversed when the pressure in the atmosphere is increasing. A higher pressure in the atmosphere does push more CO2 into the ocean surface (or gives less release)”.
Thanks for your input Ferdinand, always nice to discuss AGW with someone as level-headed and polite as you. That said, I’m not sure what relevance ‘reversed pressure’ has to do with a straightforward change in CO2’s solubility due to temperature.
Richard says:
November 29, 2013 at 10:31 am
There exists the same – about 50 times the concentration – in the water of a soda drink at very low pH compared to the trapped air under the bottle-cap than there exists in the ocean relative to the atmosphere.
There is a small difference: soda water is saturated with 3-5 bar CO2, seawater with 0.0004 bar. In both cases the ratio between free CO2 in solution and in the atmosphere is in ratio with the atmospheric pressure. But the difference is in the dissociation: in fresh water 99% is free CO2 and the rest is bcarbonate and carbonate. In seawater 1% is free CO2, 90% is bicarbonate and 9% is carbonate. Thus a change in CO2 pressure gives exactly the same change in free CO2 in both solutions, but a far greater change in the rest of DIC, thus in total DIC.
When equilibrium between DIC and atmospheric CO2 is reached, the concentration of CO2 in the oceans must be some 50 times greater than the atmosphere as determined by Henry’s law in accordance with standard physical chemistry.
Here is the Revelle factor explained:
http://www.eng.warwick.ac.uk/staff/gpk/Teaching-undergrad/es427/Exam%200405%20Revision/Ocean-chemistry.pdf
And be careful: it is not because the current partitioning between oceans and atmosphere is 50:1 that this is the “normal” ratio at equilibrium. Most of that carbon is in the deep oceans which are feeded with near freezing waters from near the poles, thus absorbing far more CO2 than the average ocean surface. Thus the deep oceans are not in equilibrium with the atmosphere, they are oversaturated. But the ocean surface layer is in near-equilibrium (an average 7 μ between air and water because of the ever increasing level in the atmosphere).
Bert Bolin 1982 for example has estimated an equilibrium time of only ¾’s of a year
That is for the surface layer only, not for the deep oceans. But the surface layer can only absorb some 10% of the change in the atmosphere. That is where the Revelle factor gets in. And as the total carbon content of the surface layer is about the same as that in the atmosphere, the uptake in the ocean surface layer is only 0.5 GtC from the 9 GtC that humans emit and of which about halve (as mass) remains in the atmosphere.