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All IPCC definitions taken from Climate Change 2007: The Physical Science Basis. Working Group I Contribution to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, Annex I, Glossary, pp. 941-954. Cambridge University Press.

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Climate Hustle

Oceans are acidifying from absorbed CO2

What the science says...

Measurements of carbon isotopes and falling oxygen in the atmosphere show that rising carbon dioxide is due to the burning of fossil fuels and cannot be coming from the ocean.

Climate Myth...

CO2 is coming from the ocean
"The solubility of carbon dioxide in water is listed in the Handbook of Chemistry and Physics as a declining function of temperature. ... The rising values of atmospheric carbon dioxide during the time of the Mouna Loa measurements could clearly be a function of reduced solubility of CO2 in the oceans of the Planet." (Watts Up With That)

We can be confident the extra CO2 in the atmosphere has come from the oxidation of fossil fuels and not from outgassing from the ocean or from soil/land sources by using two key observations.

1. Oxygen decrease

Atmospheric oxygen is going down by the same amount as atmospheric CO2 is going up. Oxygen is so abundant at about 21% (209,500 ppm) that we are in no danger of running out; the change in oxygen simply shows that whatever the source of CO2 in the atmosphere, the carbon part of it has come from the oxidation of reduced carbon compounds and the oxygen has come from oxygen gas in the atmosphere. That is, the extra CO2 was not released in the form of CO2 from an unknown source but instead some reduced carbon compound was burnt in the atmosphere to produce CO2. See: AR3WG1 Section 3.5.1, especially Figure 3.4.

2. Known fossil fuel CO2 emissions

Most obviously, any alternative explanation for the source of the CO2 in the atmosphere has to also come up with where the 30 billion tonnes of CO2 known to be released by fossil fuel burning each year goes.

Atmospheric CO2 is currently increasing at about 2 ppmv per year (or 16 billion tonnes). That is, only around half of the CO2 we release remains in the atmosphere. The pH decrease in the oceans corresponds to most of the “missing” CO2, so we can also be confident that land use changes etc are not a major source/sink. Caveat: Land use and biomass changes certainly soak up a lot of CO2, some it simply regrowth of forests etc, but the point is that the increasing CO2 in the atmosphere clearly demonstrates that they do not soak up enough.

In summary:

Amount of increased CO2
in the atmosphere
 +  Amount of increased CO2
in the oceans
  =    Amount of known fossil
fuel emissions of CO2

Acknowledgements: this post was written by New Zealand chemical oceanographer, Doug Mackie.

Update July 2015:

Here is a related lecture-video from Denial101x - Making Sense of Climate Science Denial

Last updated on 10 July 2015 by pattimer. View Archives

Printable Version  |  Offline PDF Version  |  Link to this page


Comments 1 to 11:

  1. Nice article. This one and "CO2 Pollution and Global Warming" by Barbalace represents real science. This really shows where the carbon is coming from. Since O2 has decreased, then the oceans have not warmed very much (O2 should be out gassed as well as CO2). So, the 100 ppm increase in the atmospheric CO2 may really be from fossil fuel burning from the industrial age. Nice work everyone.
  2. This is a great argument.

    The two IPCC URLs have expired; here's the new URLs:

    AR3WG1 Section 3.5.1
    Figure 3.4
  3. Could you possibly include some more info/links for the "Measurements of carbon isotopes ........ show that rising carbon dioxide is due to the burning of fossil fuels" statement please?
  4. David: Keeling, C.D. et al (2001), Exchanges of Atmospheric CO2 and 13CO2 with the Terrestrial Biosphere and Oceans from 1978-2000.

    I. Global Aspects
    II. Three-Dimensional Tracer Inversion Model to Deduce Regional Fluxes
    III. Sensitivity Tests
    IV. Critical Overview

    SIO Reference Series, Scripps Institute of Oceanography, 88 pages
  5. But Oceans outgas co2 also where does this fit in the equation?


    [TD] The exchange rates of CO2 going in and coming out of the oceans are known, along with the factors that influence those two rates.  The net effect currently still is much more going in that coming out.  See installment 9 of the OA is Not OK series.

  6. Natural sources of carbon dioxide were reported to be 770,000 metric tons by the IPCC in 2001.

    This far surpasses the anthropogenic output.


    [PS] Conveniently ignoring natural sinks as well available from same source. In short, more rhetoric and not addressing pH, isotopic composition of CO2 in atmosphere, O2 changed raised here. Your response is yet another myth debunked here.

  7. Just adding a reference on C14 measurement "Observations and modelling of the global distribution and long-term trend of atmospheric 14CO2". This demonstrates dilution of atmospheric C14 by fossil fuel burning. Also one on impact of FF burning of C14 applications in the future

  8. Sorry.... I started with a comment about me searching for the isotopic evidence that is stated in "what the science says" comment box.  It is not clear in the article's evidence however I see that a few commentors have provided links. 

    I plan to have those links tattooed to my forhead so that when I meet a rather obnoxious climate change skeptic again, like I did at a party last night, and he claims that climate science is a hoax and that any increase in CO2 is coming from the oceans, I can counter that claim and have him search the evidence as we speak.

    I jest of course.  Thank you for this website and allowing me to vent.  Climate skeptics can be frustrating, especially when they ambush with their arguments and you are 3 beers into what is supposed to be a fun night. This is my first time on this site and my first comment. I will post more valube comments in the future.


    [DB] You can find a more detailed discussion of the isotopic evidence of the atmospheric rise in concentration of CO2 on this fine post by Tom Curtis.

  9. I would be fascinated to hear how someone can claim that the CO2 increase is coming out of the ocean while at the same time CO2 dissolved in ocean in increasing (mass balance issue) and pH is decreasing. "voodoo economics" rides again? The CO2 we emit magically vanishes? Good luck - I doubt you are arguing with someone who is used to the idea that positions can be decided by data. I predict a fallback to some other argument, just as vehemently debated. Perhaps you should force them to state what data they would accept which would change their mind in advance.

  10. In my opinion, I strongly agree that the extra CO2 in the atmosphere has come from the oxidation of fossil fuels and not from outgassing from the ocean. Based from what the professionals say, CO2 emission in the atmosphere is less than half of fossil fuel emissions of CO2. Another half ends up in the ocean, which mean ocean isn't the factor of releasing CO2 to the atmosphere.

    Even there are exchanging of CO2 between ocean surface and the atmosphere. But there is a huge range of differences between going in and releasing out of CO2 from ocean. Absorbtion is a lot higher of amount.

  11. But my question is CO2 that dissolved in the ocean, even it dissolved for long time ago and also the ratio between dissolve in and release out are very different, where does the CO2 go? Is it going to be a long term effect to the ocean in the future?, thousands or millions of years after this.

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