Foreword: This is the final entry in a four part series by Fedinand Engelbeen. While the narrative is contrary to the views of many of our readers, it is within the framework of WUWT’s goal of providing discussion on the issues. You won’t find guest posts like this on RC, Climate Progress, Open Mind (Tamino), or Skeptical Science where a guest narrative contrary to the blog owner(s) view is not allowed, much less encouraged in a four part series.
That said, I expect this final entry to be quite contentious for two reasons. 1) The content itself. 2) The references to the work of Ernst Georg Beck, recently deceased.
As Engelbeen mentions below, this part was written weeks before, and readers should not get the impression that this is some sort of “hit piece” on him. Unfortunately, it simply worked out that the appearance of part 4 happens after his death, since I had been running each part about once a week. I had considered not running it, but I’m sure he would invite the discussion, and we’d have a lively debate. It is our loss that he will not be able to. For that reason, I’d appreciate readers maintaining a civil tone in comments. Moderators, don’t be shy about enforcing this. My thanks to Ferdinand Englebeen for his hard work in producing this four part series. – Anthony
About background levels, historical measurements and stomata proxies…
1. Where to measure? The concept of “background” CO2 levels.
Although there were already some hints of a “global” background CO2 level of around 300 ppmv in previous years, the concept was launched by C.D. Keeling in the fifties of last century, when he made several series of measurements in the USA. He found widely varying CO2 levels, sometimes in samples taken as short as 15 minutes from each other. He also noticed that values in widely different places, far away from each other, but taken in the afternoon, were much lower and much closer resembling each other. He thought that this was because in the afternoon, there was more turbulence and the production of CO2 by decaying vegetation and/or emissions was more readily mixed with the overlying air. Fortunately, from the first series on, he also measured 13C/12C ratios of the same samples, which did prove that the diurnal variation was from vegetation decay at night, while during the day photosynthesis at one side and turbulence at the other side increased the 13C/12C ratio back to maximum values.
Keeling’s first series of samples, taken at Big Sur State Park, showing the diurnal CO2 and d13C cycle, was published in http://www.icsu-scope.org/downloadpubs/scope13/chapter03.html , original data (of other series too) can be found in http://www.biokurs.de/treibhaus/literatur/keeling/Keeling_1955.doc :
Figure 1. Diurnal variation in the concentration and carbon isotopic ratio of atmospheric
CO2 in a coastal redwood forest of California, 18-19 May 1955, Big Sur St. Pk.
(Keeling, 1958)
Several others measured CO2 levels/d13C ratios of their own samples too. This happened at several places in Germany (Heidelberg, Schauinsland, Nord Rhine Westphalia). This confirmed that local production was the origin of the high CO2 levels. The smallest CO2/d13C variations were found in mountain ranges, deserts and on or near the oceans. The largest in forests, crop fields, urban neighborhoods and non-urban, but heavily industrialized neighborhoods. When the reciprocal of CO2 levels were plotted against d13C ratios, this showed a clear relationship between the two. Again from http://www.icsu-scope.org/downloadpubs/scope13/chapter03.html :
Figure 2. Relation between carbon isotope ratio and concentration of atmospheric CO2 in different air types from measurements summarized in Table 3.4
(Keeling, 1958, 1961: full squares; Esser, 1975: open circles; Freyer and Wiesberg, 1975,
Freyer, 1978c: open squares). All 13C measurements have not been corrected
for N2O contamination (Craig and Keeling, 1963), which is at the most in the area of + 0.6‰
The search for background places.
Keeling then sought for places on earth not (or not much) influenced by local production/uptake, thus far from forests, agriculture and/or urbanization. He had the opportunity to launch two continuous measurements: at Mauna Loa and at the South Pole. Later, other “baseline” stations were added, all together 10 from near the North Pole (Alert, NWT, Canada) to the South Pole, all of them working continuous nowadays under supervision of NOAA (previously under Scripps Institute), some 60 other places working under other organizations and many more working with regular flask sampling.
We are interested in CO2 levels in a certain year all over the globe and the trends of the CO2 levels over the years. So, here we are at the definition of the “background” level:
Yearly average data taken from places minimal influenced by vegetation and other natural and human sources are deemed “background”.
For convenience, the yearly average data from Mauna Loa are used as reference. One could use any baseline station as reference or the average of the stations, but as all base stations (and a lot of other stations, even Schauinsland, at 1,000 m altitude, midst the Black Forest, Germany) are within 5 ppmv of Mauna Loa, with near identical trends, and that station has the longest near-continuous CO2 record, Mauna Loa is used as “the” reference.
As the oceans represent about 70% of the earth’s surface, and all oceanic stations show near the same yearly averages and trends, already 70% of the atmosphere shows background behavior. This can be extended to near the total earth for the part above the inversion layer.
Measurements above the inversion layer.
Above land, diurnal variations are only seen up to 150 m (according to http://www.icsu-scope.org/downloadpubs/scope13/chapter03.html ).
Seasonal changes reduce with altitude. This is based on years of flights (1963-1979) in Scandinavia (see the previous reference) and between Scandinavia and California (http://dge.stanford.edu/SCOPE/SCOPE_16/SCOPE_16_1.4.1_Bishoff_113-116.pdf ), further confirmed by old and modern https://wiki.ucar.edu/display/acme/ACME flights in the USA and Australia (Tasmania). In the SH, the seasonal variation is much smaller and there is a high-altitude to lower altitude gradient, where the high altitude is 1 ppmv richer in CO2 than the lower altitude. This may be caused by the supply of extra CO2 from the NH via the southern branch of the Hadley cell to the upper troposphere in the SH.
From the previous references:
Figure 3. Amplitude and phase shift of seasonal variations in atmospheric CO2
at different altitudes, calculated from direct observations by harmonic analysis
(Bolin and Bischof, 1970)
From https://wiki.ucar.edu/display/acme/ACME :
Figure 4. Modern flight measurements in Colorado, CO2 levels below the inversion layerin forested valleys and above the inversion layer at different altitudes
As one can see, again the values above the inversion layer are near straight and agree within a few ppmv with the Mauna Loa data of the same date. Below the inversion layer, the morning values are 15-35 ppmv higher. In the afternoon, these may sink to background again.
If we take the 1000 m as the average upper level for the influence of local disturbances, that represents about 10% of the atmospheric mass. Thus the “background” level can be found at 70% of the earth’s air mass (oceans) + 90% of the remaining land surface (27%). That is in 97% of the global air mass. Only 3% of the global air mass contains not-well mixed amounts of CO2, which is only over land. These measured values show variations caused by seasonal changes (mainly in the NH) and a NH-SH lag. Yearly averages are within 5 ppmv:
Figure 5. Yearly average CO2 levels at different baseline stations plus a non-baseline station (Schauinsland, Germany, only values taken when above the inversion layer and with sufficient wind speed).
General conclusion:
Background CO2 levels can be found everywhere over the oceans and over land at 1000 m and higher altitudes (in high mountain ranges, this may be higher).
2. The historical data
2.1. The compilation by Ernst Beck.
Note: this comment was written weeks before we heard of the untimely death of Ernst Beck. While I feel very uncomfortable that this is published now, as he can’t react anymore on this comment, I think that one need to know the different viewpoints about the historical data, which is a matter of difference in opinion, and has nothing to do with what one may think about Ernst Beck as person.
What about the historical data? While I only can admire the tremendous amount of work that Ernst Beck has done, I don’t agree with his interpretation of the results. Not in light of the above findings of what one can see as “background” CO2 levels.
The historical measurements show huge differences from place to place, sometimes within one year, and extreme differences within a day or day to day or over the seasons for the same place. That there are huge differences between different places shows that one or more or all of these places are not measuring background CO2, but local CO2 levels, influenced by local and/or regional sources and sinks. This is clear, if one looks at the range of the results, often many hundreds of ppmv’s between the lowest and highest values. Modern measurements, sometimes interestingly done at the same places as the historical one’s, either don’t show such a wide range, and then can be deemed background for the modern ones and therefore the historical one’s must be inaccurate as method or there were problems with the handling or with the sampling. Others show huge variations also today, which means that neither the modern, nor the historical data are background.
But let us have a look at the compilation of historical CO2 measurements by Ernst Beck:
Figure 6. Compilation of historical data by Ernst Beck.
From: http://www.biomind.de/realCO2/realCO2-1.htm
Beck only gives the yearly and smoothed averages and the instrument error. That doesn’t say anything about the quality of the places where was measured, thus which of these measurements were “background” and which were not. One may be pretty sure that measuring midst of London, even in 1935, would give much higher (and fluctuating) CO2 levels than near the coast with seaside wind. Moreover, a peak of some 80 ppmv around 1942 is hardly possible, but removing such a peak in less than 10 years is physically impossible. The total amount of CO2 involved is comparable to burning down one third of all living vegetation on land and growing back in a few years time. The oceans are capable of having a burst of CO2 with a sudden decrease of pH, but simply can’t absorb that amount back in such a short time span, even if the pH would go up again (and what should cause such a massive change in pH?). Therefore I decided to look into more detail at the peak period in question, the years 1930-1950.
2.2. The minima, maxima and averages
Here is a plot of all available data for the period 1930-1950, as used by Ernst Beck (plus a few extra I did find in the literature). These can be found at his page of historical literature:
http://www.biomind.de/realCO2/historical.htm
Figure 7. Minima, maxima and averages of historical measurements in the period 1930-1950
Not all measurements were published in detail. Several authors did provide only an average, without any indication of number of samples, range or standard deviation. But for those where the range was given, the results are widely varying. What is obvious, is that where the range is small, in most cases the average of the measurements is around the ice core values (Law Dome in this case, the values of three cores, two of them with a resolution of 8 years and an accuracy of 1.2 ppmv, 1 sigma). That is especially the case for the period 1930-1935 where several measurements were performed during trips over the oceans. And even most of the worst performers show minima below the ice core values.
And as one can see, the “peak” around 1940-1942 is completely based on measurements at places which were heavily influenced by local/regional sources and sinks. That doesn’t say anything about the real background CO2 level of that period. Moreover, the fact that the average of measurements at one part of the world is 600 ppmv and at the other side of the globe it is 300 ppmv within the same year, shows that at least one of them must be at the wrong place.
2.3. The accuracy of some apparatus
Some of the measurements were done at interesting places: Point Barrow and Antarctica, where currently baseline stations are established. Unfortunately, for these measurements, the portable apparatus was as inaccurate as could be:
Barrow (1948) used the micro-Schollander apparatus, which was intended for measuring CO2 in exhaled air (some 20,000 ppmv!). Accuracy +/- 150 ppmv, accurate enough for exhaled air, but not really accurate to measure values of around 300 ppmv.
The same problem for Antarctica (1940-1941): Accuracy +/- 300 ppmv, moreover oxygen levels which were too low at high CO2 (1700 ppmv), which points to huge local contamination.
2.4. What caused the 1941 peak?
The 1941 peak is heavily influenced by two data series: Poona (India) and Giessen (Germany). With a few exceptions, the results of Poona should be discarded, as these were mostly performed within and below growing vegetation, which may be of interest for those who want to know the influence of CO2 on growth figures, heavily influenced by CO2 production from soil bacteria, but not really suitable to know the background CO2 levels of that time.
Giessen is a more interesting place, as the measurements were over a very long period (1.5 years), three samples a day over 4 heights were taken. And we have a modern CO2 measuring station now, only a few km from the original place, taking samples every 30 minutes. Thus let us see what the historical and modern CO2 levels at Giessen are, compared to baseline places:
Figure 8. Historical data of Giessen, during a few days of extra sampling to measure diurnal changes.
Figure 9. A few days in the modern summer life of CO2 at Linden-Giessen compared to the raw data from a few baseline stations for the same days.
Data for Linden-Giessen are from http://www.hlug.de
Baseline stations hourly average CO2 levels, derived from 10-second raw voltage samples, are from ftp://ftp.cmdl.noaa.gov/ccg/co2/in-situ/
These are all raw data, including all local outliers at Barrow, Mauna Loa, the South Pole and Giessen. It seems to me that it is rather problematic to figure out anything background-like from the data of Giessen, modern and historical alike. And I have the impression that Keeling made not such a bad choice by starting measurements at the South Pole and Mauna Loa, even if the latter is on an active volcano.
2.5. Estimation of the historical background CO2 levels.
Francis Massen and Ernst Beck used a method to estimate the background CO2 levels from noisy data, based on the fact that at high wind speeds, a better mixing of ground level CO2 with higher air masses is obtained (see http://www.biokurs.de/treibhaus/CO2_versus_windspeed-review-1-FM.pdf ). This works quite well, if you have a lot of data points with wind speeds above 4 m/s and a relative narrow range at high wind speeds. Here the “fingerlike” data range at high wind speed measured at Diekirch (small town in a shielded valley of Luxemburg):
Figure 10. CO2 levels vs. wind speed at Diekirch, Luxemburg.
Compare that to a similar plot of the historical data from Giessen:
Figure 11. Historical CO2 levels at Giessen vs. wind speed.
There are only 22 data points above 4 m/s, still a wide range (300 ppmv!) and no “finger” in the data at high wind speeds.
Further, the historical three samples of Giessen, taken in the morning, afternoon and evening already give a bias of some 40 ppmv (even the continuous modern sampling at Giessen shows a huge bias in averages). The afternoon measurements have a higher average than the morning and evening samples, which is contrary to almost all other measurements made in that period (and today): during daylight hours, photosynthesis lowers the CO2 levels, while at night under an inversion level, CO2 from soil respiration builds up to very high levels. And at the other end of the world (Iowa, USA) in 1940, CO2 levels of 265 ppmv were found over a maize field. Unfortunately, there are no measurements performed at “background” places in that period, except at Antarctica, which were far too inaccurate.
My impression is that the data of Giessen show too much variation and are too irregular, either by the (modified Pettenkofer) method, the sampling or the handling of the samples.
2.6. Comparing the historical peak around 1941 with other methods:
The ice core data of Law Dome show a small deviation around 1940, within the error estimate of the measurements. Any peak of 80 ppmv during years should be visible in the fastest accumulation cores (8 years averaging) as a peak of at least 10 ppmv around 1940, which is not the case (see Figure 7.).
Stomata data don’t show anything abnormal around 1940 (that is around 305 ppmv):
Figure 12. CO2 levels vs. stomata data calibration in the period 1900-1990.
From: http://igitur-archive.library.uu.nl/dissertations/2004-1214-121238/index.htm
And there is nothing special to see in the d13C levels of coralline sponges around 1940. Coralline sponges follow the 13C/12C ratios of CO2 in the upper ocean waters. Any burst and fall of CO2 in the atmosphere would show up in the d13 levels of the ocean mixed layer: either with a big drop if the extra CO2 was from vegetation, or with a small increase, if the extra CO2 was from the deep oceans. But that is not the case:
Figure 13. d13C levels of coralline sponges growing in the upper ocean layer.
2.7. Conclusion
Besides the quality of the measurements themselves, the biggest problem is that most of the data which show a peak around 1941 are taken at places which were completely unsuitable for background measurements. In that way these data are worthless for historical (and current) global background estimates. This is confirmed by other methods which indicate no peak values around 1941. As the minima may approach the real background CO2 level of that time, the fact that the ice core CO2 levels are above the minima is an indication that the ice core data are not far off reality.
3. About stomata data.
Stomata index (SI) is the ratio between the number of stomata openings to the total number of cells on leaves. This is a function of CO2 levels during the previous growing season (Tom van Hoof, personal communication). Thus that gives an impression of CO2 levels over time. As that is an indirect proxy of CO2 levels, one need calibration, which is done by comparing the SI of certain species over the past century with ice core and atmospheric CO2 measurements. So far, so good.
The main problem of the SI is the same as for many historical measurements: the vegetation of interest grows by definition on land, where average CO2 levels may vary within certain limits for one period of time, but there is no guarantee that these limits didn’t change over time: the MWP-LIA change might have been caused in part by changes in the Gulf Stream away from NW Europe, this bringing less warm wet air over land, even changing the main wind direction from SW to E. That may have introduced profound changes in type of vegetation, soil erosion, etc., including changes in average CO2 levels near ground over land.
Further, land use changes around several of the main places of sampling might have been enormous: from wetlands and water to polders and agriculture, deforestation and reforestation, all in the main wind direction, as all happened in The Netherlands over a full millennium.
Conclusion:
Stomata index data may be useful as a first approximation, but one shouldn’t take the historical levels as very reliable, because of a lack of knowledge of several basic circumstances which may have influenced the local/regional historical CO2 levels and thus the SI data.
Ferdinand Engelbeen says:
The fastest change is by vegetation: every spring CO2 levels are at maximum, falling rapidely (in the NH) when mid-latude leaves are growing and photosynthesis starts again. The opposite happens in fall, when a lot of leaves are decaying back to CO2 by soil bacteria. The opposite happens in the oceans, where summer gives more release and winters more absorption. As both act countercurrent, the net natural variability is surprisingly small: some +/- 1 ppmv from year to year, while the human emissions currently reach 4 ppmv/year and the average increase in the atmosphere is 2 ppmv/year:
http://www.ferdinand-engelbeen.be/klimaat/klim_img/dco2_em.jpg
While the seasonal change is huge (about 60 GtC back and forth for vegetation, some 90 GtC back and forth for the oceans), that doesn’t imply the possibility of a huge change in sink capacity: the earth is greening (thanks to the extra CO2), but not with 200 GtC in less than 10 years (as Beck’s 1941 peak implies), only 1.2 GtC/year extra…
What I was referring to was not the seasonal change but the year on year change at the same point in the year, i.e the trend.
The trend can change very dramatically from year to year. Therefore it is highly plausible that it could reverse with a cool ocean as Beck suggests.
Well if there is anything new on this subject that Ferdinand hasn’t addressed; I would offer that we probably don’t need to know it.
I applaud his patience in addressing the concerns of all of us who have sought clarifications or offered objections. I don’t know how you have the intestinal fortitude to address so many responses; and I am sure many times dragging up the same issues. Thansk for the Effort Fedinand.
I also noted the several visits from Eli Rabbett; and wonder why he can’t get his thoughts posted at the real Climatism sites like RC. But it’s good to see anyone coming here with ideas; on either end of the issues. I’m all for hashing out the issues in the open. That way we can all learn something.
Bob from the UK says:
September 27, 2010 at 6:06 am
What I was referring to was not the seasonal change but the year on year change at the same point in the year, i.e the trend.
The trend can change very dramatically from year to year. Therefore it is highly plausible that it could reverse with a cool ocean as Beck suggests.
The year by year natural variability is remarkably small (probably because oceans and vegetation act opposite of each other), despite the huge fluxes back and forth over the seasons: only +/- 2 GtC/year (+/- 1 ppmv) around the trend over the past 50 years. See:
http://www.ferdinand-engelbeen.be/klimaat/klim_img/dco2_em.jpg
There is little trend in the variability and the variability is mainly the result of the variability in (sea surface) temperature: a drop during the the 1992 Pinatubo eruption leading to more absorption and an increase during the 1998 El Niño, which leads to less absorption. The result is about 4 ppmv/°C variability. Again another argument that it is quite impossible that the 0.3°C peak in temperature around 1940 has caused a 80 ppmv peak in CO2.
Henry Pool says:
September 27, 2010 at 2:41 am
here is an interesting result from an experiment I did for you.
I have a swimming pool, ca. 50 m2
I filled it up to mark last week monday. Today, a week later (monday), I filled it up to mark again. I now read the meter before and after filling up.
I used 2,506 m3 (= 2506 liters) in one week. This is how much water evaporated in one week.
Note the parameters where this result applies:
no clouds, clear blue skies (for the whole week)
max. temps during the day, 31 -34 degrees C
the average water temp. in the pool was 25-26 degrees C
Compare this with my patrol (gas) consumption. I use ca. 40 liters of patrol/ month.
That is 10 liters in week
Do you understand now why I am saying that everyone in the agw crowd is barking up the wrong tree? (assuming there is something to bark about, i.e. that global warming is real and not part of a natural process)
Now look at everywhere in the world (e.g India, China, USA, Europe) where they have dams and are busy building new dams. Surely, the implications of my simple result are enormous.
So, it seems that it is your fault that we only had more rain than sunshine here since end July, with all that extra water vapour? Anyway where you live seems a much better climate than in my cool (last night already near freezing) country…
Beyond kidding: there surely will be a contribution of constructed open waters and irrigation to the global atmospheric water vapour content. The main question is how much, compared to the oceans (70% of all surface) and natural vegetation and pools, rivers and lakes. I still think that this is minor on global scale, but it can have a huge impact on regional scale, both ways (irrigation vs. cutting rainforest).
George E. Smith says:
September 27, 2010 at 10:41 am
Well if there is anything new on this subject that Ferdinand hasn’t addressed; I would offer that we probably don’t need to know it.
I applaud his patience in addressing the concerns of all of us who have sought clarifications or offered objections. I don’t know how you have the intestinal fortitude to address so many responses; and I am sure many times dragging up the same issues. Thansk for the Effort Fedinand.
Thanks for the compliment!
I suppose that all now is said that could be said. Nevertheless, if more questions remain, don’t hesitate to ask them, I only need a few hours sleep…
Now, everybody can return to his/her belief, although I hope that I could convince some more people that all effort to prove that humans are not responsible for the CO2 increase works counterproductive: The “consensus” on this is rock solid and based on many different observations which all tell the same story. Attacking that, without bringing an alternative which fits all observations, undermines the credibility of the skeptics case where the “consensus” is far from settled, like the sensitivity of climate for the CO2 increase. That is the main reason why I wrote these series.
I am a skeptic towards both what is said by the “warmers” as by the “coolers”, but I accept any good scientific facts (from any side), until new facts emerge which contradict the previous ones…
Nothing is left to say than thanking Anthony Watts for hosting this series. And I wish to thank all in this debates for the civility in tone (I have had quite different experiences in the far past with other debates on a different topic…).
Ferdinand says:The main question is how much (i.e. evaporation caused by human activities), compared to the oceans (70% of all surface) and natural vegetation and pools, rivers and lakes. I still think that this is minor on global scale, but it can have a huge impact on regional scale, both ways (irrigation vs. cutting rainforest).
I just said that taken together it must be a lot more than CO2 – remember that all energy processes including rocket fuel and nuclear as well as burning fossil fuels release water vapor in the air. Apart from that there is the added evaporation of water from man made pools and dams which, as illustrated, seems to be enormous.
It is clear that the more shallow the water, the higher the evaporation rate. The deeper the water (e.g. oceans) the more heat gets diffused to the bottom, and the less evaporation occurs.
Henry Pool says:
I just said that taken together it must be a lot more than CO2 – remember that all energy processes including rocket fuel and nuclear as well as burning fossil fuels release water vapor in the air. Apart from that there is the added evaporation of water from man made pools and dams which, as illustrated, seems to be enormous.
It is clear that the more shallow the water, the higher the evaporation rate. The deeper the water (e.g. oceans) the more heat gets diffused to the bottom, and the less evaporation occurs.
I don’t think that it is that easy. The residence time of water in the atmosphere is only a few days and any excess above the maximum humidity which the air can hold would precipitate out where temperatures are cold enough. In contrast, any excess CO2 needs some 40 years to halve the difference with the (pre-industrial) equilibrium.
At one side, more constructed water surfaces increase “human” extra water vapour, and in particular more irrigation, as the surfaces involved (and sprinkling water drops) give far more water vapour than energy use. At the other side, cutting forests, in particular rainforests, reduce water vapour emissions, as far less evaporation happens in traditional crops than from tree leaves (including the microclimate below the tree canopy). Further, the increase in CO2 reduces the number of stomata of leaves, which reduces water evaporation (and water use), as is found in deserts by researchers from Israel, which is a positive effect, thanks to the human increase of CO2…
And don’t underestimate the evaporation speed from the oceans: while any temperature increase needs much more energy than in a shallow pool, the IR part (near 50%) of the solar energy is captured in the upper fraction of a mm of the ocean surface, leading to higher temperatures of the “skin”, and also increasing direct evaporation…
But that all may not be giving higher temperatures, as cloud feedback and upper troposphere humidity changes play a larger role than the increase of water vapour in the lower troposphere. See the articles by Dr. Roy Spencer:
http://wattsupwiththat.com/2010/09/14/spencer-on-water-vapor-feedback/
and
http://wattsupwiththat.com/2010/08/28/congratulations-finally-to-spencer-and-braswell-on-getting-their-new-paper-published/
…..
OK. Good. We found a way out for all that man-made water vapor. Just one more question.
What happens when all that (man induced) water vapor condenses ? It releases energy does it not? The opposite (when water vaporises) – is that not the principle of a water cooling plant? So where does all that energy go?
Ferdinand Engelbeen says
…the variability is mainly the result of the variability in (sea surface) temperature: a drop during the the 1992 Pinatubo eruption leading to more absorption
But that is exactly the point, if the (sea surface) temperatures were to drop, to levels below that after the 1992 Pinatubo erruption, I would expect CO2 levels to decrease. After the erruption the CO2 increase was just 0.5 ppm, with an anomaly of -0.1 on average for the year. Over the decade it has been significantly higher, more like 2 ppm. Beck’s prediction was based on a SST decrease, I would approximate to be 1.5 to 2 degrees cooler than now, that would be significantly cooler than after the Pinatubo erruption. Your conclusions are based on a different expectation of a temperature trend. So if a cooling of 0.5 degree reduces the CO2 increase by 1.5 ppm, then a cooling of 2 dgrees would give you annual CO2 decreases of roughly the same magnitude as the increases we’ve seen over the last few years.
Henry Pool says:
September 28, 2010 at 2:18 am
What happens when all that (man induced) water vapor condenses ? It releases energy does it not? The opposite (when water vaporises) – is that not the principle of a water cooling plant? So where does all that energy go?
The evaporation certainly cools the tropic oceans (look what a tropical storm does over the Atlantic: http://wattsupwiththat.com/2010/09/24/igor-cool-ocean/ ) and when the vapour condensates at much higher altitude, the energy is freed, radiating a lot of energy to space. That is one of the mechanisms the earth uses to cool down the oceans if the temperature is getting too high. Other (slower) mechanisms are distribution from the equator to the poles via ocean currents and wind…
We are very lucky to live on a water planet where the different forms of water keeps the earth within (for us) habitable temperatures…
Bob from the UK says:
September 28, 2010 at 3:17 am
But that is exactly the point, if the (sea surface) temperatures were to drop, to levels below that after the 1992 Pinatubo erruption, I would expect CO2 levels to decrease. After the erruption the CO2 increase was just 0.5 ppm, with an anomaly of -0.1 on average for the year. Over the decade it has been significantly higher, more like 2 ppm. Beck’s prediction was based on a SST decrease, I would approximate to be 1.5 to 2 degrees cooler than now, that would be significantly cooler than after the Pinatubo erruption. Your conclusions are based on a different expectation of a temperature trend. So if a cooling of 0.5 degree reduces the CO2 increase by 1.5 ppm, then a cooling of 2 dgrees would give you annual CO2 decreases of roughly the same magnitude as the increases we’ve seen over the last few years.
The influence of temperature on the CO2 increase rate is some 4 ppmv/°C around the trend, that is for a (continuous) change in temperature, not for a fixed temperature (thus not 4 ppmv/°C/year). Once a new temperature is reached, the influence on the increase rate drops back to zero, simply because the average increase rate is beyond the influence of small changes in temperature.
If we may assume that the very long term ice age – interglacial CO2/temperature ratio still is applicable today for short term changes, a change of 80 ppmv only can be caused by an increase and drop in temperature of some 10°C, while the SST shows only a peak of 0.3°C around 1940, good for maximum 2.5 ppmv difference…
@Engelbeen
“Even if the first 1,000 m over land was permanently at 1000 ppmv, that hardly influences temperature rise”
I don’t think so. Increasing partial CO2 pressure by 150% in the first kilometer nearest the source of the all important 15um upwelling radiation (where there is little absorption overlap with water vapor) means that extinction would occur at a greatly reduced altitude AGL and hence raise the sensible temperature in that column of air at the expense of a lower temperature above it.
More studies of the kind by Annti Roine kind are needed, as this seems to be a crucial issue, yet it remains surrounded (as usual) by impenetrable uncertainty.
It would be good to know with more certainty some of the following:
1. What level of CO2 in the atmosphere represents pressure equilibrium with the oceans at current temperatures.
2. What the ocean absorption rate is for a given deviation from this equilibrium (say 100 ppm above equilibrium).
3. How much the absorption rate increases with larger departures from equilibrium.
Point 3, for example, might lead to the discovery of a function that sets a quick limit in our ability to keep increasing CO2 in the atmosphere through the combustion of fossil fuels.
This limit would be even quicker if there is validity to the theories that the rate at which we can extract these fuels is now at or near its limit (peak oil etc).
Another aspect of this matter I don’t hear much discussion about is this: Freeman Dyson has suggested many times that, in the very unlikely event that CO2 acumulation ever became a problem, it could be easily managed by the creation of biosinks.
E.M. Smith (The Chiefio) had a post a few years ago attempting to calculate the “scrubbing” powers of things like “fast forests,” pond scum etc. At the end of his calculations he came to some surprising conclusions which I copy below
http://chiefio.wordpress.com/2009/06/02/of-trees-volcanos-and-pond-scum/
EXCERPT:
[…]
So a “fast forest” species like Poplar or Eucalyptus can completely deplete about twice as much volume of air as sits above that forest (all the way to space) and a fertile pond growing pond scum could completely deplete about 20 times the volume of air as sits above it. In one year.
Golly.
So let me think about this for just a minute… If I grow a fast forest for 50 years, it will completely deplete 100 times the volume of air that sits above it. So 1% of the planet surface being these fast species would completely scrub all present CO2 from the air in one lifetime… 75 years in the PPM by volume case.
And pond scum could do it in 5 years. 7 and a bit years if CO2 is ppm volume. (Which I think it is, per wiki).
My Surmise
I think I know now why plants are CO2 limited in their growth. They have scrubbed the CO2 down to the point where they are seriously unable to grow well. Otherwise they would have removed it all not very long ago in geologic (or historical) time scales.
I come to 4 conclusions from this:
1) We desperately need more CO2 in the air for optimal plant growth. Plants must have depleted the air to the point of being seriously nutrient limited.
2) Any time we want to scrub the air or CO2, we can do it in a very short period of time using nothing more exotic than trees and pond scum on a modest fraction of the earth surface.
3) Biomass derived fuels will be CO2 from air limited in their production, especially if we start some kind of stupid CO2 “sequestration” projects. Siting biofuel growth facilities near CO2 sources (like coal plants) ought to be very valuable.
4) Any CO2 sequestration project that does get started by The Ministry of Stupidity needs to allow for CO2 recovery in the future. Things like ocean iron enrichment that sink it to the “land of unobtainable ocean depths” are a very bad idea. We are one generation away from CO2 starvation for our crops at any given time.
Not quite where I’d expected to end up, but enlightening all the same. Not only is CO2 increase not a problem, it is a valuable feature. And not only could we use plants to reduce CO2 in the air (if we wanted to), but we are in danger of them overdoing it all by themselves. Our biosphere is limited by the CO2 in the air and probably has been for some time.
One could speculate that the historical CO2 levels would indicate when CO2 was rate limiting for life and tell us when it was not; and thus indicate when plants were less stressed and growing much faster. It would be interesting to see if these times were followed by CO2 crashes to lower “modern” levels.
[…]
OK Ferdinand, here is a list of my unknowns:
1) whether the influence of Keeling and the throwing away of data that are 2 sigma away from the average is making nonsense of the Keeling curves, particularly if it gives a rising trend a la hockey stick ( if averages are taken backwards in time). Needs a statistician to study it.
2) How much does the soil, desert etc., absorb and release CO2 in addition to the oceans and green covered land?
3) How much CO2 falls down with rain ?
4) What if there exists a coincident in time rise in CO2 from the mantle coming out all over the earth, as a fluke, from ocean bottom to land. PH of the sea is no answer, because these will be bubbles blowing out. And we are once again on “correlation is not causation”. Are there time measurements of CO2 over volcanic re gions?
5) Human created CO2 is released 2m to 30 meters over land together with a lot of pollutants. It is a well known fact that rain is much more frequent over towns and polluted areas. How much of the human generated CO2 goes down the drains into the oceans and/or water table and never reaches the Keeling curves?
One needs satellite measurements over the globe as a function of height to make any sense of whether really the rise in CO2 observed in Mauna Loa and the rest of the Keeling curves is real and not an artifact of measurement.
Ferdinand,
you say
“when the (water) vapour condensates at much higher altitude, the energy is freed, radiating a lot of energy to space”
I think that is true – for a part but not all. Obviously when water vapor condenses we have rain. So is it not more probable: 50/50, i.e. 50% of that heat is radiated back to space and 50% back to earth?
So I am saying: there is (most probably) your real cause for global warming, if global warming is or ever does become a real problem, don’t you agree? It is the increase in water vapor caused by human activities.
In comparison, the CO2 does little nothing to the temp. on earth. In fact, if you ask me, looking carefully at the spectra, I would say that it pretty much evens between the warming (by trapping earthshine) and cooling (by deflecting sunlight) of CO2
Anyway, thanks for this discussion. It was interesting
Did you also present the works of Pielke et al, WUWT, surfacestations.org, Climate Audit, and others refuting AGW hypotheses to your students, or was this a biased presentation to your students?
If one of your students were to perform a science fair experiment demonstrating how plants in a greenhouse consume carbon dioxide and quickly reduce 1200ppm levels to about 200ppm levels in the greenhouse environment during the daylight hours of photosynthesis, what kind of grade will you give your student/s?
Dave Springer says:
September 28, 2010 at 5:41 am
@Engelbeen
I don’t think so. Increasing partial CO2 pressure by 150% in the first kilometer nearest the source of the all important 15um upwelling radiation (where there is little absorption overlap with water vapor) means that extinction would occur at a greatly reduced altitude AGL and hence raise the sensible temperature in that column of air at the expense of a lower temperature above it.
This is easily calculated with modtran, the moderate resolution transmittance program from the Archers:
http://geoflop.uchicago.edu/forecast/docs/Projects/modtran.html
Start with 395 ppmv (the current level), 1976 U.S. Standard atmosphere and 1 km height of the sensor, looking down. The result is 351.994 W/m2 going out.
Then change the CO2 level to 1000 ppmv, the rest being the same: now the outgoing radiation is 351.680 W/m2, a small decrease.
Then adjust the ground temperature offset from zero to 0.06°C: the outgoing radiation again is 351.994 W/m2. Thus the influence of 1,000 ppmv CO2 in the first 1,000 meter is only 0.06°C at worst (no feedbacks included).
As there is average far less than 1,000 ppmv in only a few hundred meters near the surface, the influence is even less…
I think I understand why you say that this piece supports a “narrative” that isn’t consistent with the views of many who read this site, Anthony, but I’m not sure I understand why you say go on to say that it is unlike the case at alarmist sites where articles contrary to the views of the blog owner(s) are blocked.
Are you saying that this piece is contrary to your own views? I can see why one might say “Wait a minute — if the temperature is changing we’ve got to account for SOME of the rising CO2 by considering the temperature-dependence of the constant in Henry’s Law”. But are you all that skeptical about the human factor as a major component in the change in CO2 levels?
As I read your writing, you are neither here nor there on the issue of whether there is a weak or strong human signature in the Keeling curve. Nor am I, for that matter. Even the guys over at co2science.org don’t appear to take issue with it.
As for myself, I regard the human contribution to CO2 levels as heroic — I credit much of the agricultural revolution that has fed the world population at levels far above what “experts” in the 1970’s said was possible, and who project being able to feed a much larger population in the decades to come, before the population is expected to peak around 2050, to increasing CO2 levels.
In my view the burning of fossil fuels merely returns carbon to the atmosphere that belongs there, but was sequestered over periods of hundreds of millions of years by the interment of biomatter. Over geological time the biosphere began to suffocate, being deprived of one of its two most fundamental airborne nutrients: O2 and CO2. I regard the last few million years as lean years for the biosphere as vegetation struggled to survive at 1/4 or less of its “normally” available CO2. I personally wonder if it wasn’t just cataclysmic events that killed the dinosaurs, but the dissipation of CO2 from the atmosphere to the point that the planet simply could no longer support the massive plant-eating behemoths and the titanic carnivores that fed upon them — animals with more efficient metabolic cycles and smaller carbon signatures took over, while plants simply hunkered down with slower growth rates, lower overall vegetative health, smaller size and more cautious photosynthesis.
As the thousands of studies referenced at co2science.org show, when even modern plants are exposed to double, triple, quadruple the CO2 in the current atmosphere the results are spectacular, and one gets what can only be described in contemporary terms as “superplants”. But this is looking at it wrong. What one gets are ordinary, healthy plants. What we see around us in the world today, beautiful and green as they may be, are a mere shadow of what they ought to be, and would be in the atmospheric environment in which they and their ancestors arose.
Mankind, by increasing the background CO2, has given the biosphere a breath of new life, as it were, and has stayed the long, slow collapse into decay and ruin, the apparently inevitable carbon suffocation of the planet. Engelbeen’s paper merely provides tangible evidence for humanity’s role in this heroic rescue.
According to NASA, “carbon dioxide is not well mixed in Earth’s atmosphere” having CO2 in concentrations from 364ppmv to 382ppmv in “the distribution of mid-tropospheric carbon dioxide” of the “free atmosphere above the surface layer.” It is going to be rather difficult it would seem to explain how the mid-tropospheric atmosphere somehow comprises less than 5% of the atmosphere, or less than 5% of the atmosphere in combination with the surface layer. It would also appear that any of your conclusions using the assumption of a well mixed carbon dioxide concentrations as a basis for conclusions must be erroneous.
D. Patterson
September 28, 2010 at 9:39 pm
According to NASA, “carbon dioxide is not well mixed in Earth’s atmosphere” having CO2 in concentrations from 364ppmv to 382ppmv in “the distribution of mid-tropospheric carbon dioxide” of the “free atmosphere above the surface layer.”
NASA has a strange definition of “not well mixed”, if the variability (within one month) is only 3% of the full range (which is btw the error margin of the NASA satellites), including seasonal differences, which are caused by back and forth fluxes of 20% of all CO2 in the atmosphere with other reservoirs.
This is what was already known from the 1970’s, see Figure 3 in the introduction. Average that over a year and the differences are less than 1% of the range within the same hemisphere, 2% between the hemispheres, mainly caused by the NH-SH lag (see Figure 5)…
And look at the differences if one plots the same data on full scale:
http://www.ferdinand-engelbeen.be/klimaat/klim_img/co2_trends_fs.jpg
That are the average CO2 levels from near the surface (Barrow and Samoa) to 3400 m high (Mauna Loa) and from near the North Pole (Barrow) to the South Pole…
If that is not well mixed, whatever can be well mixed?
Francisco says:
September 28, 2010 at 7:26 am
More studies of the kind by Annti Roine kind are needed, as this seems to be a crucial issue, yet it remains surrounded (as usual) by impenetrable uncertainty.
It would be good to know with more certainty some of the following:
1. What level of CO2 in the atmosphere represents pressure equilibrium with the oceans at current temperatures.
2. What the ocean absorption rate is for a given deviation from this equilibrium (say 100 ppm above equilibrium).
3. How much the absorption rate increases with larger departures from equilibrium.
Point 3, for example, might lead to the discovery of a function that sets a quick limit in our ability to keep increasing CO2 in the atmosphere through the combustion of fossil fuels.
I haven’t checked the figures of Antti Roine, but I suppose that either he has taken the solubility of CO2 in fresh water or he didn’t take into account what happens with the pCO2 pressure in seawater if that is absorbing some extra CO2.
If the pCO2 of the atmosphere increases with some 30% (as is the case in the past 1.5 century), that will increase the free CO2 content of the oceans mixed layer too. But free CO2 is only a very tiny part (around 1%) of total CO2 in the mixed layer. The rest are bicarbonate and carbonate ions. The total carbon (DIC) in this case is based on the sum of the three (thus CO2 + bi + carbonate) and these are in (dynamic) equilibrium which each other. Only free CO2 plays a role in Henry’s Law of solubility, but pH is influenced by the other two and if more CO2 is dissolved, the pH goes down pushing the equilibria back to more free CO2.
The net result is that for a 30% increase in the atmosphere, the increase of total carbon (DIC) in the oceans mixed layer is only 3%, with some 1,5 years delay. That makes that the current real difference in pCO2 between the atmosphere and the mixed layer is only 7 microatm in average, not 100 microatm. See:
http://www.pmel.noaa.gov/pubs/outstand/feel2331/exchange.shtml
1) If we may assume that the CO2/temperature equilibrium still is the same as found in ice cores, then the (dynamic) equilibrium CO2 level is about 290 ppmv for the current temperature.
2) Near zero at zero wind speed… The problem with CO2 is that the diffusion speed in water is very, very low. Thus the best mixing is by wind, which moves water around from depth to the surface, including thorough mixing with air at the surface. See Fig. 5 in:
http://www.pmel.noaa.gov/pubs/outstand/feel2331/maps.shtml
The difference in pCO2 between oceans and atmosphere is heavily dependent of temperature: much higher near the equator (outgassing) and much lower near the poles (uptake). But also pH, salt content and (bi)carbonate content play an important role.
3) The oceans mixed layer is readily saturated with extra CO2 from the atmosphere. The real excape route is via the THC sink directly into the deep oceans. But that has a limited capacity. The current net absorption of the oceans is about 2.5 GtC from the 8 GtC emissions. With the current (still increasing) emissions, there is no sign that the increase rate in the atmosphere is decreasing (maybe temporarely with the economic crisis), the above ratio remains more or less the same. Only if the emissions wouldn’t increase further, we may expect that the increase rate of CO2 in the atmosphere would decrease and reach zero at a certain level of CO2.
anna v says:
September 28, 2010 at 8:12 am
OK Ferdinand, here is a list of my unknowns:
1) whether the influence of Keeling and the throwing away of data that are 2 sigma away from the average is making nonsense of the Keeling curves, particularly if it gives a rising trend a la hockey stick ( if averages are taken backwards in time). Needs a statistician to study it.
2) How much does the soil, desert etc., absorb and release CO2 in addition to the oceans and green covered land?
3) How much CO2 falls down with rain ?
4) What if there exists a coincident in time rise in CO2 from the mantle coming out all over the earth, as a fluke, from ocean bottom to land. PH of the sea is no answer, because these will be bubbles blowing out. And we are once again on “correlation is not causation”. Are there time measurements of CO2 over volcanic re gions?
5) Human created CO2 is released 2m to 30 meters over land together with a lot of pollutants. It is a well known fact that rain is much more frequent over towns and polluted areas. How much of the human generated CO2 goes down the drains into the oceans and/or water table and never reaches the Keeling curves?
One needs satellite measurements over the globe as a function of height to make any sense of whether really the rise in CO2 observed in Mauna Loa and the rest of the Keeling curves is real and not an artifact of measurement.
1) One don’t need to be a statistician to see that it doesn’t make any damn difference if you throw out outliers or not: the difference in yearly average between all data, including outliers, and “cleaned” data is less than o.1 ppmv (I have checked it for 2006). Here the magnified graphs of Mauna Loa and the South Pole where the raw hourly averages and the “cleaned” daily and monthly averages of 2008 are plotted together:
http://www.ferdinand-engelbeen.be/klimaat/klim_img/co2_mlo_spo_raw_select_2008.jpg
Thus the cleaning method itself has no influence at all on the trend, as if the average is somewhat too low one year, that adds in the next year increase (the satellite data btw show the same trend over the past years).
2) That is part of the biosphere. While there are huge uncertainties about the fluxes, the net absorption or release of CO2 to/from the biosphere can be deduced from oxygen use. That shows a net uptake of 1.4 +/- 0.8 GtC/year in the period 1991-1997.
3) Hardly known, but as far as I have read, rain slightly increases momentary CO2 levels, as the raindrops were saturated during condensation (at lower temperatures) and some water evaporates on the ground (and temperature increases somewhat).
4) d13C levels of most volcanic CO2 is at the “high” side e.g. the Solfatara crater near Naples (-1.3 per mil d13C) compared to the atmosphere (-8 per mil). That would increase the d13C levels in the atmosphere, but we see a decrease…
On several places of the earth CO2 outgassing of the earth crust is monitored around volcanoes:
http://www.nature.com/nature/journal/v344/n6261/abs/344051a0.html
http://volcanoes.usgs.gov/lvo/activity/monitoring/co2.php
5) No idea, but not important at all, as that just is part of the total sink of around 4 GtC from the 8 GtC emissions. As the total sink is calculated as the difference between calculated emissions (from fossil fuel sales) and the measured increase, one doesn’t need to know any details of any individual flow of CO2.
The satellite measurements (average above the inversion layer) show similar trends as the Keeling curve:
http://www.nasa.gov/images/content/411794main_slide8-AIRS-full.jpg
Including the ground level variations will increase the noise, but will not change the trend, as (also nowadays) the mixing of the ground level variations with the rest of the atmosphere is a matter of hours to days…
NASA says “AIRS can observe the concentration of carbon dioxide in the mid-troposphere, with 15,000 daily observations, pole to pole, all over the globe, with an accuracy of 1 to 2 parts per million….” Now 1-2ppmv is far less than what you are claiming for “the error margin of the NASA satellites.”
Something far less than the actual observed 364ppmv to 382ppmv in “the distribution of mid-tropospheric carbon dioxide” of the “free atmosphere above the surface layer” will do nicely. Also, your numbers don’t add up where you ignore how this 18ppmv unequal distribution is in the mid-tropospheric free atmosphere and comprises considerably more than the something around 3% to 5% portion of the atmosphere you keep claiming is not background levels of carbon dioxide concentrations. NASA says it is not well mixed, after you denied it was well mixed. NASA reported AIRS accuracy of 1-2ppmv, while you deny such satellite accuracies. You claim the higher carbon dioxide concentrations occur over the continental lnd masses, whereas the satllites show the carbon dioxide is occuring over the oceans in proximity to the continental lnad masses and not in proximity to the continental land masses.
You are salso still trying to claim you can actually calculate how much carbon dioxide enters and leaves the sinks, yet you still completely fail to account for the way in which plant life voraciously consumes carbon dioxide to near extinction of photosynthesis. You act as if there is a delicate balance between the capacity of the biosphere to remove carbon dioxide from the atmosphere versus the sources of emissions to the atmosphere. The reality of a closed greenhouse reveals to any biologist studying photosynthesis in plants that the biosphere has far more capacity to consume carbon dioxide over short periods of time than there is in the prsent atmosphere to consume. You have also failed to explain how it is possible for the 182.5ppmv to 198ppmv observed in the Vostok ice cores te accurately represent carbon dioxide concentrations in the last 800,000 years when such low levels would have caused a mass extinction of life on the planet which has never been observed in the geological record.
D. Patterson says:
September 29, 2010 at 8:04 am
NASA says “AIRS can observe the concentration of carbon dioxide in the mid-troposphere, with 15,000 daily observations, pole to pole, all over the globe, with an accuracy of 1 to 2 parts per million….” Now 1-2ppmv is far less than what you are claiming for “the error margin of the NASA satellites.”
The error margins claimed in the early days of the satellite measurements were +/- 10 ppmv, compared to ground based stations. It is possible that they increased the accuracy by calibrating against ground stations and inflight measurements. No problem with that.
Something far less than the actual observed 364ppmv to 382ppmv in “the distribution of mid-tropospheric carbon dioxide” of the “free atmosphere above the surface layer” will do nicely. Also, your numbers don’t add up where you ignore how this 18ppmv unequal distribution is in the mid-tropospheric free atmosphere and comprises considerably more than the something around 3% to 5% portion of the atmosphere you keep claiming is not background levels of carbon dioxide concentrations. NASA says it is not well mixed, after you denied it was well mixed. NASA reported AIRS accuracy of 1-2ppmv, while you deny such satellite accuracies. You claim the higher carbon dioxide concentrations occur over the continental lnd masses, whereas the satllites show the carbon dioxide is occuring over the oceans in proximity to the continental lnad masses and not in proximity to the continental land masses.
You are mixing up a lot of things:
1) No dateline is given for the pictures with the wide range of +/- 9 ppmv, probably a short period (one day?). The monthly average for July 2009 only shows a range of +/- 4 ppmv, which difference can be seen between land based stations too for monthly averages for the same month. See:
http://www.nasa.gov/images/content/411791main_slide5-AIRS-full.jpg
and
http://www.ferdinand-engelbeen.be/klimaat/klim_img/month_2002_2004_4s.jpg
2) Momentary (daily) differences of +/- 10 ppmv are peanuts if the ground based differences over land (5% of the atmosphere) can differ with several hundred ppmv within a few hours (see Figure 9 of the introduction). I thought that I made it clear that “well mixed” doesn’t imply that CO2 levels at any moment everywhere are exactly the same. That would only be possible if there were no huge sources and sinks at work. If the NASA means with “not well mixed” that there are (relative modest) variations within a day or a few days, then they are right. But that is not the definition of “background” Keeling and I used: background levels can be found in 95% of the atmosphere, where yearly CO2 averages are minimal influenced by natural and human influences.
I haven’t seen yearly averaged CO2 levels from the AIRS satellite data yet, but I suppose that these will show less that 2 ppmv within each hemisphere and less than 5 ppmv between the NH and SH, as also the ground stations show.
3) That the CO2 levels are higher near land masses over the oceans simply shows that the CO2 levels leaving the ground are rapidely (!) mixing into the winds circulating West to East all over the mid-latitudes. While Barrow still is freezing like hell, CO2 levels increase in spring, simply because CO2 comes in from the mid-latitudes with the air circulation from the Ferell cells.
4) If a doubling of CO2 over the full air column (290 to 580 ppmv) has only a direct influence of some 0.9°C (without feedbacks), what do you think that the influence of +/- 10 ppmv difference (over a day, month, year) will be?
You are salso still trying to claim you can actually calculate how much carbon dioxide enters and leaves the sinks, yet you still completely fail to account for the way in which plant life voraciously consumes carbon dioxide to near extinction of photosynthesis. You act as if there is a delicate balance between the capacity of the biosphere to remove carbon dioxide from the atmosphere versus the sources of emissions to the atmosphere. The reality of a closed greenhouse reveals to any biologist studying photosynthesis in plants that the biosphere has far more capacity to consume carbon dioxide over short periods of time than there is in the prsent atmosphere to consume. You have also failed to explain how it is possible for the 182.5ppmv to 198ppmv observed in the Vostok ice cores te accurately represent carbon dioxide concentrations in the last 800,000 years when such low levels would have caused a mass extinction of life on the planet which has never been observed in the geological record.
To begin with, the carbon (as CO2) content of the atmosphere is 800 GtC. The carbon content of the whole terrestrial biosphere is about 600 GtC. If that increased substantially in short term, one would see a drop of CO2 of the atmosphere. But there is no drop at all. Only a deficit of 4 GtC from the 8 GtC emissions. Based on the oxygen balance, there is some 1.4 GtC uptake by the biosphere, the rest is going into the oceans. Thus whatever the local uptake may be from new planted forests, the global uptake is not more than 0.2% of the total biomass currently present.
Different plant species like grasses and grains developed the C4 photosynthesis. C4 plants like maize still show a net photosynthesis at 100 ppmv.
C3 plants will have more problems with low CO2 levels, but they have one escape…
As all terrestrial plants live on land by definition, CO2 levels increase at night, thanks to soil bacteria. Even if that drops fast to low background (180 ppmv) in the morning sun, at least a few hours of photosynthesis are possible. And when background levels are higher, the day heat gives enough turbulence to refresh at least a part of the CO2 at ground level. Again see the CO2 levels at Linden/Giessen of Figure 9.
Further, I found older works (1943) which investigated plants at low CO2 levels, until respiration and uptake were in equilibrium (thus no more growth). That included grain, alfalfa and sugar beets. Depending of temperature (the lower the temperature, the lower the CO2 equilibrium), the minimum equilibrium for grain and alfalfa was around 80 ppmv, for sugar beet around 60 ppmv. See
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC438162/pdf/plntphys00280-0194.pdf
I didn’t find back if alfalfa and sugar beet are C3 or C4 plants, grain anyway is a C4 plant…
@Engelbeen
Modtran with default settings (375ppm CO2) except for altitude changed to 1km gives me 406.316 w/m^2 (not the number you claimed – you must have screwed up the settings somehow).
I changed the CO2 setting to 999999 (pure CO2) just to see what would happen and got a reading of 401.606 w/m.
Then I changed it to 1ppm and got a reading of 406.944 w/m
Then I changed the altitude to 20km and 999999ppm CO2 and got a reading of 201.243.
The interesting thing about the last reading is that the shoulders broadened to extinguish 400 wavenumbers.
Going from 1ppm to 999,000ppm CO2 in the first kilometer of air changed the output only 5 w/m^2!
I don’t trust the physics and/or the programming behind the Modtran model farther than I can throw it. It gives ridiculous results. In engineering (I understand you’re an engineer) we call what I did with the model a “sanity test”. It didn’t pass.