Why the CO2 ice core reconstructions matter.

In my last article I was primarily discussing a dependency that the rate of CO2 levels in the atmosphere has on the rate of global temperature change.  This came up because of a recent podcast and pending paper by Dr. Murry Salby.  His paper shows that human activity is not responsible for the increasing level of CO2 in the atmosphere.  I will admit that I was very skeptical about his claim initially, but I am now open to the idea that he is correct in this.  One of the reasons I was skeptical is the paleoclimate data that shows low CO2 levels in the Earth’s past.

I fully agree with the assertion that CO2 is dependent on temperature (ocean temperature specifically)  and I have shown why this is in the past.  What I had not considered was that the entire baseline for CO2 could be incorrect.   What the ice cores really provide though is a natural ceiling for the total ‘natural’ level of CO2 in the atmosphere.  The ice cores used by warmists show that for the past 400,000 years the level of CO2 never exceeds 300 ppm.  The highest recorded value in the Vostok ice core is 298.7 ppmv which was for YBP 323,485.  If that data is accepted, then values higher than that today must be unnatural.  That is certainly what warmists like to show.

The ice cores are popular because they produce measurements that are in the same units of measure as atmospheric CO2 levels.  As Dr. Salby and others have pointed out, this does not actually mean that the measurements are correct.  The Vostok ice core is everywhere when it comes to CO2 and temperature.  If that one ice core were proven to underestimate the CO2 by any significant amount, the entire AGW argument collapses into dust.

That made me start looking around.  For all the talk about CO2, there is a surprising lack of paleoclimate data on that peskly gas, but what I have been able to find is interesting.  The GISP2 (Greenland) has some interesting results, especially when compared to what Dr. Salby has said.

The Inconvenient Skeptic

(Green) GISP2, (Red) Vostok CO2 ppmv

The GISP2 ice core has 120 data points between 10,200 – 16,490 YBP.  The Vostok ice core has only 6 data points for the same range.  Yet it is the Vostok ice core that dominates the discussion.  The GISP2 also has 324.8 ppmv which is the same level that Mauna Loa recorded for 1969.  GISP2 said that was the same level that happened 10,960 YBP.  There is also the evidence of the high frequency changes when the period from 11-19K years ago is looked at.

The Inconvenient Skeptic

GISP2 CO2 ppmv data by ice core depth. The depths associated are: 1900m ~= 19,000 YPB, 1650m ~= 11,100 YBP

There is a period between 1700-1800m that high frequency oscillations are present in the CO2 data.  There is even 300+ ppmv as far back as 13,500 YBP.  That provides a very different story than what is being told.    This does not prove that Vostok is wrong and GISP2 is correct, but it certainly does indicate that there is certainly more reason to look into this further.  I am also now collecting C13 isotope data that is out there and those results will be shown in the future.

I am still proceeding cautiously on this line of research.  Even if the conclusions are solid a year from now that the Earth’s changing CO2 levels are natural, it will not change the debate by very much.  The usual suspects are so well entrenched that they will simply be able to ignore the data and plead to the public that it just doesn’t make sense that all the giga-tons of CO2 are not causing the increase.  They will make that case while still throwing the flat-earth anti-science label on anyone who disagrees.  This would still not explain why the Earth is warming either.

If this is proven out, then to me it will just be one of many, many reasons that the Theory of Global Warming is incorrect.  This will simply be the most amusing of those reasons.

Posted in Cause and Effect and Measurement Methods and Skeptic by inconvenientskeptic on August 8th, 2011 at 10:33 am.


This post has 5 comments

  1. I understand CO2 to be a well-mixed gas in the atmosphere, but is it possible that regional variations affect the concentrations?

    Just wondering if thinks like temperature, humidity, other particles, etc. can affect how much CO2 gets trapped when layer of ice forms…. I know, call me crazy.

  2. You might find this paper from Nature of interest:


  3. inconvenientskeptic Aug 8th 2011


    The number I keep hearing is no more than 5%

    Of course regionally in the northern hemisphere there is greater annual fluctuation than that. The measurements from the US show 6-7% difference between June and October some years.

    The other factor that is more important is that Greenland is near a large sink of cold water. That would cause Greenland to be towards the low end of the range.

  4. Todd,
    Look up “CO2 diffusion in polar ice: observations from naturally formed CO2 spikes in the Siple Dome (Antarctica) ice core” by Jinho Ahn et al. from the Journal of Glaciology (2008). A pretty relevant paper. If you google it you should be able to find a free download. I have a copy if you can’t find it.

  5. Bruce Aug 8th 2011

    Chiefo wrote about C4/C3 metabolism plants and C12/C13 carbon ratio.


    Wikipedia suggests 30% of terrestrial carbon is fixed because of C4 plants … like corn and sugar can.

    And C4 plants prefer C13 …. possibly enough to change the C12/C13 ratio.

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