Thursday, July 17, 2014

New paper finds only ~3.75% of atmospheric CO2 is man-made from burning of fossil fuels

CORRECTED POST of "New paper finds only ~3.75% of atmospheric CO2 is man-made from burning of fossil fuels":

Thanks to notification from and email conversations with the lead author Denica Bozhinova of the paper "Simulating the integrated summertime Δ14CO2 signature from anthropogenic emissions over Western Europe, the claim made in the original Hockey Schtick post that ~3.75% of background atmospheric CO2 is man-made from burning of fossil fuels is hereby retracted due to a misinterpretation of the paper. The author has clarified that her paper does not address the mole fraction or concentration of CO2 of fossil fuel origin present in background levels of CO2, it addresses the mole fraction or concentration of CO2 of fossil fuel origin of recent emissions only. 

Regarding the conclusion of the paper which states in part
"...the 6-month average CO2ff concentrations in the lower 1 km of the atmosphere across Western Europe are between 1 to 18 ppm."
I asked the author via email
"My understanding now is that CO2ff in your paper is referring to the concentration of CO2ff that is above background levels of CO2 rather than absolute concentrations of CO2ff, thus please confirm my understanding is correct that your conclusion may be stated as "...the 6-month average [CO2 concentrations of fossil-fuel origin that are above background concentrations of CO2] in the lower 1 km of the atmosphere across Western Europe are between 1 to 18 ppm," and that it is not possible to determine from your data the absolute concentrations of CO2 of fossil fuel origin [background + recently added]."
and the lead author has replied in her 3rd email today
"Your last paragraph describing the complicated fossil fuel/background relationship used in study is in fact totally correct. I am sorry that probably it is not going to be of use for your draft, however I am certain that there are other studies that investigate the issue you were trying to address."
I apologize for my misinterpretation of the paper, putting the post in draft mode during email conversations back and forth with the author, and all subsequent confusion which I caused. I'd like to thank lead author Denica Bozhinova for her kind and detailed emails [portions below], apologize for the time she has spent correcting my misinterpretation and that of several others in the blogosphere, and wish her all the best in her future career and research. 

Original post follows with retracted portions, along with the abstract and conclusions from the paper:

A paper published today in Atmospheric Chemistry and Physics finds that only about 3.75% [15 ppm] of the CO2 in the lower atmosphere is man-made from the burning of fossil fuels, and thus, the vast remainder of the 400 ppm atmospheric CO2 is from land-use changes and natural sources such as ocean outgassing and plant respiration.

According to the authors, 
We find that the average gradients of fossil fuel CO2 in the lower 1200 meters of the atmosphere are close to 15 ppm at a 12 km × 12 km horizontal resolution.
The findings are in stark contrast to alarmist claims that essentially all of the alleged 130 ppm increase in CO2 since pre-industrial times is of man-made origin from the burning of fossil fuels, finding instead that only 15 ppm or ~11.5% of the increase is of fossil fuel origin. The findings cast additional doubt upon the IPCC carbon-cycle Bern Model, previously falsified by the atomic bomb tests. 

Furthermore, if use of fossil-fuels has contributed such a small part of total atmospheric CO2 levels, restricting use of fossil fuels will have little effect upon CO2 levels. 

Full paper open access:

Atmos. Chem. Phys., 14, 7273-7290, 2014

D. Bozhinova1, M. K. van der Molen1, I. R. van der Velde1, M. C. Krol1,2, S. van der Laan3, H. A. J. Meijer3, and W. Peters1
1Meteorology and Air Quality Group, Wageningen University, the Netherlands
2Institute for Marine and Atmospheric Research Utrecht, Utrecht, the Netherlands
3Centre for Isotope Research, University of Groningen, Groningen, the Netherlands

Abstract. Radiocarbon dioxide (14CO2, reported in Δ14CO2) can be used to determine the fossil fuel CO2 addition to the atmosphere, since fossil fuel CO2 no longer contains any 14C. After the release of CO2 at the source, atmospheric transport causes dilution of strong local signals into the background and detectable gradients of Δ14CO2 only remain in areas with high fossil fuel emissions. This fossil fuel signal can moreover be partially masked by the enriching effect that anthropogenic emissions of 14CO2 from the nuclear industry have on the atmospheric Δ14CO2 signature. In this paper, we investigate the regional gradients in 14CO2 over the European continent and quantify the effect of the emissions from nuclear industry. We simulate the emissions and transport of fossil fuel CO2and nuclear 14CO2 for Western Europe using the Weather Research and Forecast model (WRF-Chem) for a period covering 6 summer months in 2008. We evaluate the expected CO2 gradients and the resulting Δ14CO2 in simulated integrated air samples over this period, as well as in simulated plant samples.

We find that the average gradients of fossil fuel CO2 in the lower 1200 m of the atmosphere are close to 15 ppm at a 12 km × 12 km horizontal resolution. The nuclear influence on Δ14CO2 signatures varies considerably over the domain and for large areas in France and the UK it can range from 20 to more than 500% of the influence of fossil fuel emissions. Our simulations suggest that the resulting gradients in Δ14CO2 are well captured in plant samples, but due to their time-varying uptake of CO2, their signature can be different with over 3‰ from the atmospheric samples in some regions. We conclude that the framework presented will be well-suited for the interpretation of actual air and plant 14CO2 samples.

Excerpts from the conclusions:

In this work, we demonstrated the ability of our modeling
framework to simulate the atmospheric transport of CO2
and consequently the atmospheric 114CO2 signature in integrated
air and plant samples in Western Europe. Based on
our results we reach the following conclusions.

1. Simulated spatial gradients of 114CO2 are of measurable
size and the 6-month average CO2ff [CO2 from the burning of 
fossil fuels] concentrations in the lower 1 km of the atmosphere
across Western Europe are between 1 to 18 ppm.

2. Enrichment by 14CO2 from nuclear sources can partly
mask the Suess effect close to nuclear emissions, particularly
in large parts of UK and northwestern France.
This is consistent with previous studies (Graven and
Gruber, 2011) and we show that in these regions the
strength of the nuclear influence can exceed the influence
from fossil fuel emissions.

3. The simulated plant 114CO2 signatures show spatial
gradients consistent with the simulated atmospheric
gradients. Plant growth variability induces differences
between the simulated plant and the daytime atmospheric
mean for the period of growth, of a magnitude
that is mostly within the measurement precision of
±2 ‰, but can be up to ±7‰ in some areas.

4. Integrated 114CO2 samples from areas outside the immediate
enrichment area of nuclear emission sources
are not sensitive to occasional advection of enriched air
due to their long absorption period. However, to properly
account for the nuclear enrichment term on smaller
time scales, improvements in temporal profiles of nuclear
emissions are needed.

5. New 114CO2 sampling strategies should take advantage
of different sampling methods, as their combined
use will provide a more comprehensive picture of the
atmospheric 114CO2 temporal and spatial distribution.

Additional details from selected excerpts of email conversations with the lead author Denica Bozhinova:

From the author:

...The background term in our equations, as I tried to explain in my
reply on the Hockey Schtick, includes all the CO2 and its respective
∆bg signature that has been in the atmosphere before our simulation
start or has been transported into our modeled area from outside
during the simulation. As such it combines all the previously emitted
and transported anthropogenic and natural CO2 and in our study we
cannot distinguish the fractions that can be attributed to the
different sources in this term. It defines the starting CO2 level in
our modeled area and how the transport from outside would affect it.

All the other terms (biospheric respiration, uptake, fossil fuel and
nuclear 14CO2 emissions) are implemented with surface fluxes only
(described explicitly in our section 2.2). That means that they are
the recently added or removed quantities with a particular source/sink
within the time and space of our simulation. And as such when we
average the results for the 6 months we obtain a spacial map (for
CO2ff much alike the one shown in Figure 4a, except there the scale is
in ∆14CO2) in which for the lower 1 km of the atmosphere the average
concentrations of CO2ff are between 1 and 18 ppm AND at the same time
the average (spatial, since we average over the time) gradients in the
concentrations of the CO2ff in the lower 1200 km are about 15 ppm.

From HS:

...My understanding now is that CO2ff in your paper is referring to the concentration of CO2ff that is above background levels of CO2 rather than absolute concentrations of CO2ff, thus please confirm my understanding is correct that your conclusion may be stated as "...the 6-month average [CO2 concentrations of fossil-fuel origin that are above background concentrations of CO2] in the lower 1 km of the atmosphere across Western Europe are between 1 to 18 ppm.", and that it is not possible to determine from your data the absolute concentrations of CO2 of fossil fuel origin [background + recently added].

Thanks once again for your assistance and please accept my sincere apologies.

From the author:

Thank you for the apology and in my turn, I apologize if I have been a
bit too harsh in my response to you. Truth is, this is the first time
when I had to deal with so much publicity regarding one of my works
and it was very difficult to read the people's opinions of the article
and its scientific merit, even when I realized that they were based
mostly on the review only. As a scientist one must learn how to take
criticism to one's work, but it doesn't necessary mean it is easier to
do it.

I would also like to thank you for the general attempt to translate
scientific words and work for the wider audience. Even if the review
of my particular article was a bad example, a misstep, such work is
crucial for the future of science as communication between scientists
and the general public is a really important and extremely difficult
task. One that most of the scientists can't do themselves either or
are really poor at.

Your last paragraph describing the complicated fossil fuel/background
relationship used in study is in fact totally correct. I am sorry that
probably it is not going to be of use for your draft, however I am
certain that there are other studies that investigate the issue you
were trying to address.

I did mean that most authors would be eager to reply to questions
about their work, especially immediately after an article has come out
of publication. This is probably especially true for young researchers
like me (not a Dr. yet), for which such contact provides the almost
priceless feedback that their work is relevant or interesting for
someone else than just other scientists.

Kind regards,
Denica Bozhinova

Dept. of Meteorology and Air Quality

Wageningen University and Research Center
Building 100 (Lumen), Room A1.16
Droevendaalsesteeg 3 6708 PB
P.O. Box 47, 6700 AA, Wageningen, The Netherlands


  1. There's a difference between the half-life of a CO2 molecule in the air (which is quite short), and the half life of a jump in CO2 intensity in the air (which is much longer). This is due to the constant exchange of CO2 between the surface and the air.

    Could this be the reason for the result?

    1. "Half life of CO2" Are you nuts? The discussion is not on radioactivity. Go back to Jesus, but read about the Wohler Synthesis of 1832 and perhaps, but only perhaps, you will understand.

    2. Not half-life of CO2 but half-life of Carbon-14 an isotope of carbon with a half-life of over 5000 years..

  2. 1. Segalstad et al find there is little difference (only a few years) between CO2 residence-time ~5-7 years and CO2 lifetime ~14-17 years. The notion that CO2 lifetime is "a thousand years or more" is based upon the highly-flawed IPCC Bern Model.

    2. If CO2 lifetime was truly 1000+ years, fossil fuel derived CO2 should be much higher than 3.75%, as alarmists have claimed in the past using incorrect interpretations of C13/C14 ratios.

    1. Since 1832 we have known that all molecules are the same, no matter the source. This discussion belongs in an Alchemy text.

    2. The CO2 molecule is made up of three atoms and one is carbon. But there is Carbon-12 and two isotopes Carbon-13 and Carbon-14.

      This article is about Carbon-12 and Carbon-14. Unfortunately the researchers omitted Carbon-13 which is taken up by plants and marine organisms.

    3. Agreed that the Bern model is flawed, as that is based on the saturation of the deep oceans. But the 5 years residence time is irrelevant and the 14 years lifetime is too short: that is based on the decay rate of the 14C spike of the 1950's atomic bomb tests. But the huge exchange with the deep oceans (~40 GtC/year) which is 500-1500 years old is a lot lower in 14C than the bomb spike, which makes the decay rate of 14C a lot faster than the decay rate of the human "spike", about a factor 3.

  3. I really don't get "nuclear CO2" or the "nuclear emissions" that this paper mentions. Could somebody post a comment that briefly explains that?

    1. Nuclear power plants release mainly as a gas a harmless isotope of CO2 called 14CO2!/Menu/general/column-content/attachment/Magnusson_Doctoral_thesis_2007.pdf

    2. Fossil fuels are so old that there is no Carbon-14 left. So it is easy to distinguish CO2 from fossil fuels and CO2 from nuclear reactors.

      Carbon-13 is found in plants and the shells of marine animals and foraminifera.

  4. I find it hard to believe that the atmosphere went from 280ppm to 400ppm predominantly due to natural causes. Maybe true but fails my sniff test.

    1. I see, your sniff test is better than objective measurements of isotopes in the atmosphere

    2. The 1,000 volcanoes that go off every year produce a major amount of the 166 gigatons produced on Earth every year. Man makes six of them, 3.22%, a fact that is in every geophysical text and reference.

    3. As examples both melting ice and oceans release CO2 exponentially as they warm so increase is very easily explained by fact higher CO2 levels caused by temperature increase which has relatively little to do with CO2 levels...

    4. @Anonymous,

      Which also correlates with the fact that sea water contains CO2 in concentration 3,000 times that of the atmosphere. It takes only but a very slight change in ocean temperature to have a very large impact to atmospheric CO2 concentration. Precisely how atmospheric CO2 concentration has been around 3,000ppmv for the better part of the past 10,000 years.

    5. Not saying that it's outgassing from the oceans, but Henry's law applies to Coca Cola too.

      When the Coke warms up the CO2 bubbles away and you get flat pop.

      There is also CO2 from volacanoes, something that has always made me feel uncomfortable about the measurements at Mauna Loa. Mauna Loa is the largest subaerial volcano in both mass and volume, and has historically been considered the largest volcano on Earth.

      Over geological time volcanoes have been the main source of carbon dioxide and the oceans the main carbon sink. The current geological period is one of the lowest ever in CO2 density and plants are relatively starved of CO2. Possibly 1500 parts per million would suit plants much more than the measly 400 ppm they get now.

      Humans manage quite well up to about 8000 ppm.

    6. Squidly and others, it doesn't matter how much CO2 is in the oceans, what matters is the pressure difference. If you shake a 0.5, 1.0 or 1.5 liter bottle of Coke from the same batch at the same temperature, you will see the same pressure under the cork (slightly less in the smaller bottle due to the larger loss in the smaller amount of liquid). Henry's Law for seawater gives some 17 microatm more CO2 pressure for 1 K temperature increase. Thus an increase of ~17 ppmv in the atmosphere will fully compensate for the increase in temperature. Except if you think that the oceans have heated a lot more than 1 K since the LIA. That is the maximum increase from warming oceans... Vegetation goes the other way out, thus reducing the CO2 in the atmosphere for increasing temperatures (to about 8 ppmv/K in combination with the oceans)...
      The rest of the 100+ ppmv is from humans.

    7. This paper's claim is difficult to believe. What happened to the ~1500 Gt CO2 the world has emitted from burning fossil fuels?

      I expect someone willl find a major error in this paper soon.

    8. What happened to the 3-4% of CO2 emissions from man?

      The global greening of the planet, for one.

  5. Look at this table from EIA:

    It shows that only about 3% of CO2 in atmosphere is human sourced.

    1. Correct, those are (estimated) emissions, yet the airborne fraction of man-made CO2 has been decreasing

      Both the airborne fraction decrease and that man-made CO2 emissions = current man-made CO2 levels at 3-4% suggest the rise of CO2 levels is primarily natural, and that CO2 lifetime is much less than the IPCC claims.

    2. The IPCC has been publishing a lot of nonsense about CO2. Mount Pinatubo put out more new CO2 in a year than man did in 150 years or burning fossil fuel. That one volcano is responsible for most of the increase and every honest scientist paying attention knows it, but they also know from where the grant money comes and how much they want new taxes and more of our money.

      Google "Two Minute Conservative" and when you speak they will listen.

    3. Adrian, your Pinatubo claim is wrong. It emitted only 0.05 Gt CO2; man now emits about 35 Gt CO2. See:

      "Volcanic vs Anthropogenic Carbon Dioxide," T Gerlach, EOS v92 n24, June 14, 2011.

  6. Adrian Vance, that is absolute malarkey. Pinatubo outgassed a paltry 1/20 Gt (EPA via Gerlach, 2011 - That's 700 times less than humans emit in any given year.

    1. IMHO modelers accounted for cooling between the 1940's and 1970's by really juicing volcanic aerosol emissions.
      Those aerosol quantities, heavily sulfur oxides were greatly exaggerated to fit the paradigm.
      Obviously, if SOx emissions were high so would be the CO2. Not commenting on this paper, just making a point of alarmist speak from both sides of the coin.

    2. No, not volanic aerosols. Manmade aerosols (before air pollution controls).

  7. Did you notice this research is a simulation? As in a guess computed using a model. It is therefore not factual data about measurements collected in nature., so you can't present this as evidence of the sources of CO2.

  8. So a large part of the CO2 is due to plants... and thanks to human technology more of the planet is covered by plant life now than it was a hundred years ago... so the CO2 is kind of man-made!

  9. The natural world is actually a net absorber of our CO2 emissions, which of course is why the oceans are becoming more acidic. Hence 100% of the rise in atmospheric CO2 since the pre-industrial is anthropogenic. That means current atmospheric CO2 is 30% anthropogenic, not 3%. An order of magnitude error in the study's results is quite impressive!

    1. "The natural world is actually a net absorber of our CO2 emissions, which of course is why the oceans are becoming more acidic"

      The oceans are alkaline, not acidic, and scant evidence of a decrease in ocean pH

      "Hence 100% of the rise in atmospheric CO2 since the pre-industrial is anthropogenic. That means current atmospheric CO2 is 30% anthropogenic, not 3%."


      The airborne fraction of man-made CO2 has decreased over the past 60 years

      and this paper finds the fraction of current atmospheric levels from fossil fuels = fraction of current emissions from fossil fuels, thus no build-up of anthropogenic CO2.

    2. "The oceans are alkaline, not acidic, and scant evidence of a decrease in ocean pH."

      All chemical compounds have a property called "acidity," and when it increases it is perfectly proper to say it is acidifying.

      There is a symetric argument for alkalinity. But "debasification" is a mouthful, and obscures the point. There is ample evidence of a declining pH, with significantly more to come. It's basic chemistry.

    3. The airborne fraction of human emissions varies from year to year, but didn't change much in average over the past 55 years, still 50-55% of human emissions:
      That means that nature was a net sink of CO2 over the past at least 55 years.

      The whole article is about the human part in the total carbon circulation, but that says next to nothing about the cause of the increase in the atmosphere, but the airborne fraction does...

      If someone opens a supply valve in the circulation over a fountain that adds 1 l/minute while the circulation over the fountain is 1000 l/minute, the fountain certainly will overflow if he forgets to close the valve in time, even if that is only 0.1% of the supply...

    4. BTW, the airborne fraction is a matter of two competing forces: the extra pressure of CO2 in the atmosphere compared to the "equilibrium" pressure for the current temperature, which forces more CO2 into the oceans (and plant uptake) and the effect of the extra pressure and temperature on the in/out fluxes.
      If we take the pressure difference as base, for the current 110 ppmv extra (231 GtC extra), the net result is ~2 ppmv (4.15 GtC) extra uptake by nature. Over the past 55 years that gives following curve of the airborne fraction as function of pCO2(atm) - pCO2(equi):
      Still largely within natural variability (here as 12-month running mean).

    5. Appell: For a substance to become "more acidic" it has to be acidic i.e. pH < 7.0 to begin with. The more correct terminology for an alkaline substance such as seawater at pH ~8 is "less alkaline" or "less basic" because it will still be alkaline.

      "Acidification" is off-topic for this thread - please comment on one of the many acidification threads, where you will also find many links demonstrating that there is no reliable evidence that ocean pH has actually decreased, and that the "basic chemistry" you claim to be so simple is actually quite complicated due to the presence of numerous buffering systems in the ocean.

    6. Hansen's data shows that since 1960, man-made CO2 emissions have increased by a factor of 4, yet the airborne fraction of man-made CO2 has decreased 25% from 60% to 45%.

      Quoting Hansen: "However, it is the dependence of the airborne fraction on fossil fuel emission rate that makes the post-2000 downturn of the airborne fraction particularly striking. The change of emission rate in 2000 from 1.5% yr-1 to 3.1% yr-1 (figure 1), other things being equal, would have caused a sharp increase of the airborne fraction (the simple reason being that a rapid source increase provides less time for carbon to be moved downward out of the ocean's upper layers)." But, it did not, according to Hansen because carbon sinks like CO2 fertilization of plants compensated by greening the planet. There is no evidence that such carbon sinks will stop compensating in the future, that the greening of the planet will not continue thanks to CO2 emissions.

      The new paper in this post shows the total cumulative man-made contribution of CO2 is only 15%, due to erroneous prior assumptions about C14 levels in the atmosphere, failing to recognize the significant C14 source from nuclear power. Only ~11% of the increase in CO2 levels was from fossil fuels, 89% from primarily natural sources.

      The significant decrease in airborne fraction over the past 50 years with man-made CO2 emissions increasing 400% clearly demonstrates man-made CO2 is not the primary source of the increase in CO2 levels. This new paper corroborates by showing current man-made CO2 levels are approximately equal to the percentage of man-made emissions, thus the primary cause of the CO2 increase is clearly not due to man.

  10. As the lead author in the cited scientific article ( ), I would like to address several key points of our study, which I believe were misunderstood by the author of this blog entry and are misleading the readers.

    (1) The paper does not state that (quote from the blog) "only ~3.75% of atmospheric CO2 is man-made from burning of fossil fuels", this thought was constructed by the blog-writer and conclusions drawn from it are entirely his/her own.
    (2) The paper does not state that (quote from the blog) “only 15 ppm or ~11.5% of the increase (in CO2 since pre-industrial times) is of fossil fuel origin”. This again is a creation by the blog-writer.

    As it is quite challenging to untangle the information extracted from our article and the conclusions, which the author of this blog is drawing from it, I hope for your patience in reading this undoubtedly long reply.

    It might be easiest to point out first that the cited sentence („We find that the average gradients... “) from our abstract, which is possibly the centerpiece in this blog entry, is preceded in the article by several sentences explaining the temporal and spatial scope of our study – 6 summertime months in 2008 over Western Europe.

    This explanation should already address the misconception that the cited 15 ppm of fossil fuel CO2 are the global average concentrations and cover the historical period since the pre-industrial era. Rather the opposite, those are the gradients in the newly added fossil fuel CO2 concentrations in Western Europe within the 6 month period covered in our study.

    If you read the research article carefully you will find that the phrase used in both title and front-running paragraph of this blog entry ("only ~3.75% of atmospheric CO2 is man-made from burning of fossil fuels") is nowhere to be found in our article. This is because we aim at evaluating only the recently added anthropogenic CO2 to the atmosphere in a particular region of the world.

    All the older (previously added, both anthropogenic and natural) CO2, as well as the CO2 being added during the 6 months of our study but outside of our research region are included in the term 'background CO2' in our study. This crucial point might have been overlooked by the blog-writer as we are using terminology and methods from previously published research (with provided references) that he/she might have not looked into. It is common and good practice in our field to use previously defined terminology.

    I appreciate all the feedback and scepticism about our results as shown by the commenters here. I would, however, ask the author of the blog entry to try and be more careful in his summary of this and other scientific studies, especially when he makes claims about the findings that are nowhere in the article itself.

  11. Thanks for setting the record straight!

    P.S. It is Denica ;)

    1. Thank you too for all your help, and I just noticed I've been misspelling your first name as Denika instead of Denica. I'll correct that as well. It's been one of those weeks...

  12. Thanks HS.

  13. Dear (future Dr.) Bozhinova, thanks for the clarification! Anyway it has triggered a lot of discussion here and at WUWT. I hope you enjoyed the sometimes fierce arguments of all sides in the quite diverse group that the skeptics are. And I hope that you in your later work will remember that discussions are the part of science that keeps science healthy: a "consensus" kills scientific progress, critique and discussions do advance science...

    BTW, was several times near Wageningen, biking through the Veluwe, beautiful in August-September... And I had a few discussions with Tom van Hoof from Wageningen University about the reliability of stomata data as CO2 proxy...