Engelbeen on why he thinks the CO2 increase is man made (part 3)

In this case it is. Methane is generated at the surface but it decomposes into CO2 in the stratosphere. How do those particular CO2 molecules deposited directly into the stratosphere make it back down to the surface to be sucked up by a CO2 sink?
Obviously it never does, it just stays up there forever and ever, after all, it took, oh, a whole ten years or so for the CH4 to get to the stratosphere in the first place.

Dave Springer says:
September 17, 2010 at 6:56 pm
“There is some error in reasoning here: input is not accumulation!”
In this case it is. Methane is generated at the surface but it decomposes into CO2 in the stratosphere. How do those particular CO2 molecules deposited directly into the stratosphere make it back down to the surface to be sucked up by a CO2 sink? Conversely CO2 generated by fossil fuels are generated primarily on the surface in close proximity to CO2 sinks.
I don’t see the problem: while CO2 from methane is mainly formed at the troposphere-stratosphere border from oxydation by hydroxyl radicals and ozone (both formed by UV radiation), there still is an exchange of air between the stratosphere and troposphere: up in the tropics and down near the poles, including stirring up wherever there are tropical storms. See (already from 1995):
http://www.ems.psu.edu/~brune/m465/strattropdynholton.pdf
That there is atmospheric mixing between the two layers is also visible in the opposite way: ground level based seasonal exchanges can be measured even in the lower stratosphere with some year delay:
http://www.ferdinand-engelbeen.be/klimaat/klim_img/seasonal_height.jpg
Lower stratosphere CO2 levels measured during regular (commercial) flights Scandinavia – Boston.
And stratospheric CO2 levels simply follow the near ground CO2 level increase, again with a delay.
About the influence of the extra methane induced CO2 on isotopic changes:
If we may use the 10 years half life of the extra human induced methane CO2, that means that of the current 11oo ppbv extra CH4, some 0.11 ppmv CO2 is formed per year at -40 per mil d13C. Humans currently emit 4 ppmv CO2 per year at -24 per mil average. Thus the release of human CH4 is currently responsible for 2.7% of the CO2 increase per year, but some 5% of the d13C decrease. This ratio was somewhat higher in the early days of the (pre)industrial revolution, but both increased near in parallel.
As the oxygen derived sink rates still have large margins of error (+/- 50% for biogenic uptake and +/- 30% for ocean uptake), the influence of human methane releases is largely within the error margins.
Anyway, as the increase of methane levels is quite surely human induced (as good as land use changes), I don’t see a problem for the original point, that oxygen levels and changes in isotopic levels exclude the oceans ánd vegetation as main sources for the increase of CO2 in the atmosphere.
Dave Springer says:
September 17, 2010 at 8:49 pm
I’m not sure I agree with that but it disputes your position that accumulation doesn’t count.
I never said or implied that accumulation doesn’t count, to the contrary. Indeed accumulation is all what counts. The accumulated emissions and the accumulation in the atmosphere show a near perfect match over the past 100+ years:
http://www.ferdinand-engelbeen.be/klimaat/klim_img/acc_co2_1900_2004.jpg
As there is not much difference in CO2 levels between the different atmospheric layers, the exchange of CO2 from different sources between the air layers is much faster than you expect, from months to a few years (about one year for the lower stratosphere to 5 years for the mid-stratosphere). See:
http://onlinelibrary.wiley.com/doi/10.1111/j.2153-3490.1973.tb00615.x/pdf
and
http://www.nature.com/nature/journal/v316/n6030/abs/316708a0.html

FYI all
Detailed breakdown of anthropogenic methane emissions by source and country plus 20 year forward projections:
http://www.epa.gov/methane/excel/methane_baselines.xls
Abatement technologies, costs, and other characteristics by source and country:
http://www.epa.gov/methane/excel/techtbls.xls
Too bad the biggest producers of methane are countries that aren’t going to sign up for abatement. The US is already doing a lot of methane abatement unilaterally and voluntarily.
As an experiment a global cap & trade on methane emissions makes some sense because it might be possible to measure the result in global temperature anomaly. CO2 has such a long residence time in the atmosphere if we were to curtail emissions in any reasonable quantity it would be 100 years (if at all) before we could tell if it helped or not whereas with methane abatement we might be able see a result in 20 years or less.
In any case if the serious desire is to actually reduce greenhouse gas effect rather than a serious desire to control the world through controlling energy production and consumption then the only thing that makes sense is methane abatement as that is easily the most cost effective and quick way to reduce it.
The problem appears to be that the ideological interests in controlling energy production and use vastly outweigh the genuine interest in mitigating global warming so CO2 remains the focal point where the CAGW cabal applies the pressure.
What a revolting situation. Money and power, as usual, are the determining factors while the objective science and engineering which should be the determining factors are left by the wayside.

@Engelbeen
You are quite wrong about how quickly troposphere and stratosphere mix. Experimental results show the mean lifetime of stratospheric methane to be between (roughly) 70 and 110 years.
From the Journal of Geophysical Research (Atmospheres)
[my emphasis]
http://europa.agu.org/?view=article&uri=/journals/jd/97JD02215.xml
Evaluation of source gas lifetimes from stratospheric observations
C. M. Volk, J. W. Elkins, D. W. Fahey, G. S. Dutton, J. M. Gilligan,
M. Loewenstein, J. R. Podolske, K. R. Chan, M. R. Gunson,
Simultaneous in situ measurements of the long‐lived trace species N2O, CH4, 12, CFC‐113, CFC‐11, CCl4, CH3CCl3, H‐1211, and SF6 were made in the lower stratosphere and upper troposphere on board the NASA ER‐2 high‐altitude aircraft during the 1994 campaign Airborne Southern Hemisphere Ozone Experiment/ Measurements for Assessing the Effects of Stratospheric Aircraft. The observed extratropical tracer abundances exhibit compact mutual correlations that show little interhemispheric difference or seasonal variability except at higher altitudes in southern hemisphere spring. The environmental impact of the measured source gases depends, among other factors, on the rate at which they release ozone‐depleting chemicals in the stratosphere, that is, on their stratospheric lifetimes. We calculate the mean age of the air from the SF6 measurements and show how stratospheric lifetimes of the other species may be derived semiempirically from their observed gradients with respect to mean age at the extratropical tropopause. We also derive independent stratospheric lifetimes using the CFC‐11 lifetime and the slopes of the tracer’s correlations with CFC‐11. In both cases, we correct for the influence of tropospheric growth on stratospheric tracer gradients using the observed mean age of the air, time series of observed tropospheric abundances, and model‐derived estimates of the width of the stratospheric age spectrum. Lifetime results from the two methods are consistent with each other. Our best estimates for stratospheric lifetimes are 122 ± 24 years for N2O, 93 ± 18 years for CH4, 87 ± 17 years for CFC‐12, 100 ± 32 years for CFC‐113, 32 ± 6 years for CCl4, 34 ± 7 years for CH3CCl3, and 24 ± 6 years for H‐1211. Most of these estimates are significantly smaller than currently recommended lifetimes, which are based largely on photochemical model calculations. Because the derived stratospheric lifetimes are identical to atmospheric lifetimes for most of the species considered, the shorter lifetimes would imply a faster recovery of the ozone layer following the phaseout of industrial halocarbons than currently predicted.

Larry says:
September 16, 2010 at 7:45 am
Isn’t this trying to prove that the majority of increased co2 is from man, not that man is the cause of the increase? Clearly if man is producing 4molecules per 1000 and the atmospere is increasing by 2 per 1000 there is something else going on there.
[snip]
That is not to say the concentration has not been increased by man, but in effect you would have to prove first that concentrations of co2 in the atmosphere would be different if man had not burnt the fuels. As soon as you are involved with feedbacks – which clearly you are because the concentration increase does not increase the amount produced by man – showing the cause of the co2 in the atmosphere does not prove that if man had not burnt the fuel the concentration would have been less.
Put in simpler terms, if we had not burnt the carbon more co2 may have been gassed from the oceans to compensate, because the current temperature requires more co2 in the atmosphere.
The ice cores show convincingly that the “natural” equilibrium was influenced by temperature changes at about 8 ppmv/°C during the past 800,000 years. That makes that the equilibrium CO2 level at current temperatures was around 290 ppmv. We are currently at 390 ppmv and we see that nature absorbes 2 ppmv CO2/year at current CO2 levels. That proves that we are currently above the natural equilibrium of the CO2 cycle.
Indeed the higher level of CO2 suppresses the oceanic outgassing near the equator and increases the uptake of CO2 near the poles (and by vegetation), near perfectly in ratio to the total increase. That doesn’t prove that without human emissions there wouldn’t be any increase of CO2 in the atmosphere, but according to 800,000 years of history, that is not very likely.

Thanks. I was beginning to think my eyes had gone funny, or my brain.
JF

Matt G says:
September 18, 2010 at 7:44 am
& Julian Flood says:
Yes, you are indeed correct that delta 13c starts to decline well before 1850 on figure 4.
Well, may be right, but up to about 1850 you are looking at the natural variability of d13C levels (+/- 0.1 per mil), only beyond that date, the “fossil” signal becomes large enough to be seen beyond the natural “noise”.
Methane levels even increased from 600 to 700 ppbv in the period of 6000 years ago to 1850 (after that sky rocketing to 1800 ppbv). Some see that as a proof that agriculture (rice) had already such an influence on methane levels…

tallbloke says:
September 16, 2010 at 7:49 am
Hi Ferdinand, thanks for a clearly written article which appears to use good logic as far as it goes. I have a couple of questions.
1) You told us in an earlier installment that the ‘natural’ increase in co2 due to the earth being a degree warmer than it used to be would be around (IIRC) 20ppm (from oceanic de-gassing). But co2 has risen @110ppm from @280 to @390. If we are responsible for around half of that increase, 55ppm, and the expected natural increase due to oceanic de-gassing is 20ppm, what is responsible for the other @35ppm?
Humans have added near 200 ppmv in the past 160 years, thus halve that would be 100 ppmv increase. Thus humans are responsible for (almost) all of the increase…
2) If the answer to 1) is “we don’t know”, then how do we know that the mystery factor wouldn’t cause more than 35ppm extra if we weren’t pumping fossil fuel produced co2 into the atmosphere? i.e. if there is a non-linear process at work, how do we know it wouldn’t ‘take up the slack’ if we emitted less?
We do know the cause(s) of the increase, but what will happen if we stop all emissions today is more controversial: some claim a 5 years half life time (but that is based on the refresh rate of 150/800 GtC per year, nothing to do with a decay rate), others about 40 years (seems more plausible) and the IPCC claims different half life times between slightly over a year and many hundreds of years. All three claim that there will be a drop if we stop all emissions today. The near 40 years half life time is based on the current CO2 levels and the current sink rate of about 45% of the emissions, which is quite constant over the past 100+ years, thanks to the slightly exponential increase rate of the emissions…

Doug Proctor says:
September 16, 2010 at 9:04 am
HelmutU says:
September 16, 2010 at 6:58 am :
That the IPCC minimum contribution of anthopogenic CO2 is 21%, and that the signature should, by this calculation, be -11%, but is actually -8%, up from -7% (my computer doesn’t appear to have a mill sign). It is this conclusion I was looking for with all the graphs and discussion of mechanisms. I didn’t see it.
The recyling of fossil fuel CO2 is certainly a concern. The half-life of CO2 is a big deal. The removal process is proportional in some fashion to the total concentration, so we will continue to see a signature after introduction into the atmosphere. Another factor with a large uncertainty.
The fine points of the math are beyond not just me, but many others. Could we see someone working out:
a) the current, cumulative contribution of CO2 from fossil fuels post 1850 and 1945 (the start of so much was being dumped in the air) based on the isotopic data,
b) the incremental increase year-to year as a proportion of 2 ppm, from this isotopic data, and
c) the proportion of CO2 from fossil fuels incrementally added AFTER taking into consideration the half-life of CO2 and the changed proportion of fossil fuel CO2 in the previous year’s atmosphere?
No worry, I have worked it out, assuming a quite realistic half life time of 38 years for an excess amount of CO2 in the atmosphere (based on the current 4 GtC sink rate per year for an excess 100 GtC, see the basic calculation at http://www.john-daly.com/carbon.htm ) and a refresh rate of 150/800 GtC/year.
The decay rate with a 38 years half life influences the total amount (whatever the type or origin) of CO2 residing in the atmosphere, while the refresh rate influences the isotopic composition (or what rests of the CO2 of fossil origin in the atmosphere). Deep ocean – atmosphere exchanges estimated at 40 GtC/year (based on the resulting isotope changes). For the past 160 years of emissions that gives following plot:
http://www.ferdinand-engelbeen.be/klimaat/klim_img/fract_level_emiss.jpg
Where tCA is the total amount of CO2 in the atmosphere, calculated and observed and FA% the fraction of “fossil” CO2 in the atmosphere in percent and FL% the fraction of fossil CO2 in the ocean mixed layer.
With the same assumptions, one can compare what the d13C levels should do by adding the emissions and what they really have done over the past 160 years:
http://www.ferdinand-engelbeen.be/klimaat/klim_img/d13c_calc_obs.jpg
Again A is atmospheric and L is mixed ocean layer.
This is not a perfect match, but not far away either, it needs some incorporation of what vegetation probably did do (not included yet) with the d13C ratio’s.

re; methane
It appears the science isn’t quite as settled as one might imagine.
Near as I can tell the oxidization the atmosphere is the primary sink and is driven by UVB. Where that happens and at what half-life appears to depend on a lot on where it was emitted. Nearer the equator is a high source of emissions both natural (wetlands) and manmade (rice farming). This is largely swept up into the stratosphere by strong convection cells with stratospheric tops. From there it is transported poleward where it sinks. The poles are very intense in UVB (ozone holes) and UVB is stronger in the stratosphere. Given the higher UVB environment on this route it appears to have a lifetime of about 5-7 years in this route. Emissions away from the equator, which are just as large from both natural (wetlands) and manmade (mining & agriculture) sources, mix horizontally in the troposphere very well but tend not to be driven up through the tropopause at near the rate happening around the equator. Presumably these have a longer half-life as they spend longer mixing horizontally in a lower UVB environment. The stratosphere isn’t as dry as it would be without manmade methane. The 5ppm water vapor content of the stratosphere is believed to be mostly due to CH4 + 2 O2 -> CO2 + 2 H2O.
A huge enigma exists in that for 10 years from 1998-2007 methane content in the atmosphere stopped rising. Methane has increased about 150% on what appears to be a smooth curve that correlates well with rising anthropogenic production. However there’s yet another confounding factor which is methane clathrates (methane trapped in permafrost and ocean sediments – a staggering amount of it and where rising temperature must release some portion of it. Another confounding factor is the Little Ice Age which ended right about when the industrial revolution began. A transition from a cooler earth that persisted for several centuries to the first two centuries of a warmer earth has to be taken into account. The transition would necessary entail release of methane from methane ice and increased generation from more wetland activity. On the other hand the warmer earth would presumably have a higher methane transport rate through the atmosphere.
In any event it’s becoming clear that methane plays a GHG role half that of CO2. Moreover whereas anthropogenic activity adds just a few percent to the total carbon cycle it more than doubles the natural methane cycle. And since methane has a much shorter half-life in the atmosphere if we were to focus on limiting methane instead of CO2 we’d get a much bigger bang for our buck and we’d see presumably measurable results in the next decade. And if we didn’t like the result we could undo it just as quickly.
In the meantime we should probably relax (relax not eliminate) the rules on SO2 emissions (everyone remembers or knows about acid rain, right?) as studies show anthropogenic sources can have a marked cooling effect. SO2 has a rather short half-life as well so it’s much more amenable to experiments that may be undone. Selectively removing or throttling industrial SO2 smokestack scrubbers to get a higher global emission rate without concentration in any smaller area sufficient to make acid rain a problem seems like a cheap way to get a measure of global cooling. We can also selectively change the mix of low of high sulfur diesel to get an increased but well distributed atmospheric SO2 rise.
The thing of it is that methane and SO2 mediation doesn’t appeal to politicians because it is cheaper and easier and doesn’t have huge tax & control opportunities like CO2 has. As well, it doesn’t appeal to Malthusian ideologists either because there isn’t much change in civilization that goes along with it. So we find ourselves stuck trying to regulate CO2 emission which is politically impossible globally and regionally only by nations willing to give up economic competitiveness for what will amount to nothing more than a futile gesture.
Nearer the equator it is largly swept up into the stratosphere from convection and getting past the tropopause with the aid of high topped convective cells (thunderstorms, hurricanes

George E. Smith says:
September 16, 2010 at 9:22 am
The NASA map certainly puts the Kibosh on the notion that CO2 in the atmospehre is well mixed; and that appears to be a starting assumption in climate models. It clearly isn’t even approximately well mixed. To me; well mixed would eman that no matter where or when I took a sample of the atmosphere and analysed it, I would get the same composition on a molecular species (and isotopic) basis; at least within limits of differences that are of no consequence to any climate argument; and of course excluding taking a sample up somebody’s tailpipe or chimney.
You would be right if there were no variable sources and sinks at work. As about 20% of all CO2 is going back and forth between the atmosphere and other reservoirs over the seasons, then it is no wonder that there are differences in CO2 levels between altitudes and latitudes over a year, even for a well mixed gas. The above AIRS satellite data are the average only for one month mid-summer. A similar plot for mid-winter would show the opposite picture with lower levels in the NH than in the SH. Yearly averages are far more even over the globe (in over 95% of the atmosphere), with a slight lag of the SH (which points to the main source of extra CO2 in the NH). See:
http://www.ferdinand-engelbeen.be/klimaat/klim_img/co2_trends.jpg
And as the AIRS plot shows: a variability of +/- 10 ppmv on a scale of near 400 ppmv is hardly a proof of bad mixing, see the raw data and “cleaned” daily averages of two stations (NH and SH near the equator) for the year 2008 at full scale:
http://www.ferdinand-engelbeen.be/klimaat/klim_img/co2_raw_select_2008_fullscale.jpg
One thing does puzzle me. The oceans and the atmosphere are presumably somewhat near equilibrium in the Henry’s Law sense as to the segregation of CO2 between atmosphere and ocean. And we are told that the carbon in deep water storage, is not getting out into the atmosphere. So why is it that the CO2 isotopic composition of the near surface ocean water, and the near surface atmosphere don’t match. Is somebody claiming (proof please) that the Henry’s Law Segregation at the interface is highly isotope dependent. I haven’t heard that claim made before. Why isn’t the ocean exchanging exactly the same isotopic CO2 with the atmospehre whether releasing or taking up ?
The physical explanation is a matter of difference in mass, therefore velocity and speed of transfer between air and water (and reverse) at the air-water border layer. See:
http://dge.stanford.edu/SCOPE/SCOPE_16/SCOPE_16_1.5.05_Siegenthaler_249-257.pdf
Besides that, there is some exchange of CO2 between the deep oceans and the atmosphere via the THC sink in the NE Atlantic and the upwelling in the mid-Pacific (and other sink/source places), but these are indeed quite limited in capacity.

Dave Springer says:
September 20, 2010 at 9:22 am
Unless I’m reading that wrong the ocean fractionates very little when it absorbs CO2 but emits CO2 that is 5x as light. Something in the ocean is sinking carbon 13 and thus making the atmosphere lighter.
It is a physical process, the difference in mass and therefore (migration and evaporation) speed which makes that there is fractionation, as good as is the case for “heavy” water (D2O) and heavy oxygen (18O) water. The reverse process seems less selective.
The net difference is -8 per mil between ocean water and atmosphere for a full cycle, but more with extra degassing and less with extra absorption. Depending of the source, the deep ocean upwelling would give a net atmospheric d13C level of -7 to -8 per mil, while surface water would give -4 to -7 per mil, due to the higher d13C levels in the surface caused by biolife. The net result in the pre-industrial past of all such movements was around -6.4 +/-0.1 per mil in the atmosphere.
Currently we are at -8 per mil. Thus one-way deep ocean upwelling would decrease the d13C level of the atmosphere (a two way source and sink would be near break-even), but as deep ocean upwelling also is an extra source of nutritients, that increases biolife in the upper oceans and thus 12C removal. The net result of this all would be a d13C increase in the atmosphere, while a decrease is observed…
Further, the oceans are currently a net sink for CO2, which also should increase the d13C level of the atmosphere, while we measure a decrease…
That makes that the oceans can’t be the cause of the CO2 increase in the atmosphere, neither of the d13C decline.
And if you combine all facts, the case of the human contribution (fossil fuel combustion, methane emissions, land use changes) is quite solid, as that fits all observations…