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Vostok Ice Core / CO2 correlation - an AGW myth demolished

Jonathan Drake has released an interesting paper called A Simple Method to Correct Carbon Dioxide Concentrations in Ice Core Data for Ice / Gas Age Difference Perturbations.

Before you skip to the next item tarry a while because this is interesting. He had a look at the Vostok ice core data / CO2 correlation, one of the great poster children of the AGW movement.

The ice core data as presented goes back 420,000 years. Various parameters can be measured from it, or inferred. It is understood that the age of the gas (air) trapped is generally younger than the ice containing it and therefore this difference needs to be determined. This is done using models of the system and the measured parameters.

As he says:
For the purposes of my paper, I use IGD, for the ice age to gas age difference. What I noticed was that IGD appeared to move with the CO2 measurement (correlation). I looked for a relationship between IGD and CO2 and found it was close to linear, so I calculated the linear trend. Now using this mathematical function, I adjusted the CO2 levels so that they represent the concentrations at an arbitrary IGD = 0 because this corresponds to what the level of CO2 ought to be had it been trapped at the time the snow hit the ground. A secondary effect of this is to correct the time reference. At IGD = 0, the ice and gas are the same age by definition.

So once the compensation I describe is applied, the resultant CO2 levels are very different to the original, both in level and character. It appears that, for some reason, the temperature is modulating the original CO2 data.
In the corrected version, there is virtually no correlation between temperature and carbon dioxide.

I leave you to draw your own conclusions regarding how this relates to the AGW story.

I like to look at it this way: the original data is like a tail wagging the dog, and the corrected version analogous to the dog wagging its tail.

The pdf of his paper is here.

Comments

That's interesting but I don't think you can call something "Demolished" on the strength of this alone.

Is there any mechanism that can be suggested to explain why IGD would be linked to systematic errors in CO2 measurement? Alternatively, is there any mechanism which would link actual CO2 concentration with IGD? Presumably IGD is due to air moving either within the ice or into the ice from the air after the ice is formed - I could imagine this would depend on temperature or precipitation rates.

I'm not saying Drake is wrong, just that we can't use this in a political argument until it's been questioned in this way. If it could get published properly that would be an indication that it had stood up to some sort of challenge.

Unfortunately, from where I am it's password protected.

The concentration of CO2 in ice depends upon its solubility which is a function of temperature (see abstract below). Thus, the measured CO2 concentrations may actually just be a proxy for temperature for the most part. This may explain Drake's findings.

CO2 in Natural Ice

By Stauffer, B & Berner, W

Natural ice contains approximately 100 ppm (by weight) of enclosed air. This air is mainly located in bubbles. Carbon dioxide is an exception. The fraction of CO2 present in bubbles was estimated to be only about 20%. The remaining part is dissolved in the ice. Measurements of the CO2 content of ice samples from temperate and cold glacier ice as well as of freshly fallen snow and of a laboratory-grown single crystal were presented. It is probable that a local equilibrium is reached between the CO2 dissolved in the ice and the CO2 of the surroundings and of the air bubbles. The CO2 content of ancient air is directly preserved neither in the total CO2 concentration nor in the CO2 concentration in the bubbles. Possibly the CO2 content of ancient air may at least be estimated if the solubility and the diffusion constant of CO2 in ice are known as a function of temperature. (See also W79-09342) (Humphreys-ISWS)

(From: Symposium on the Physics and Chemistry of Ice; Proceedings of the Third International Symposium, Cambridge (England) September 12-16, 1977. Journal of Glaciology, Vol. 21, No. 85, p 291-300, 1978. 3 fig, 5 tab, 18 ref.)

A noble effort to make a correction, however, I would suggest readers look carefully at the work of a leading glaciologist - Zbigniew Jaworowski. CO2 can never give an accurate reading in ice cores because the CO2 can escape from the ice because of the great pressures at depth, lquid water is common in polar ice and CO2 is extremely soluble in cold water and the various gases within the air cannot combine or separate.
Surely the basic physics of CO2 should really be enough to convince anyone, even a politician, that this minor gas cannot produce anything but a few tenths of a degree over decades.
With the difficulties of measuring accurate global mean temperatures isn't it time the general public wised up to the fact that they are being conned.
CO2 taxation; fuel price rises; carbon emission trading; biofuels; renewable energy - ask yourself who benefits. Joe Bloggs? It's time the general public got together to rebel against this charade.

Both the PDF links above just give garbage ... any ideas welcome.

w.

Well, I took a look at the paper. He seems to be saying that we can "adjust" the CO2 based on the ice age/gas age difference (IGD).

The problem with that is that the IGD is calculated from the temperature at the time the snow was originally falling. The higher the temperature, the more snow falls, and the shorter the IGD. Since the CO2 levels have a correlation with the temperature, this means that the IGD will also be correlated with CO2.

However, this does not mean that we can "adjust" the CO2 based on the IGD. All this will do is show us what the CO2 would be like if the temperatures were constant for the period of record. If the temperature were constant, we'd expect the CO2 level to be relatively flat.

And as you might assume, his result shows that ... but so what? All he has shown is that CO2 and temperature are correlated, but we knew that already.

That paper belongs in the dustbin of scientific history. He's just using the IGD as a proxy for the temperature. All his paper shows is that if the temperature were constant over the ice ages, the CO2 levels would be pretty constant as well.

w.

Dr. Roy Spencer included in his testimony before the US Senate Environment and Public Works Committee on 22 July 2008 the statement “…I am predicting today that the theory that mankind is mostly responsible for global warming will slowly fade away in the coming years, as will the warming itself…” His complete testimony can be seen at http://epw.senate.gov/public/index.cfm?FuseAction=Files.View&FileStore_id=e12b56cb-4c7b-4c21-bd4a-7afbc4ee72f3 . He points out flaws in the Global Climate Models. GCM models are the only indicators that human added carbon dioxide is a significant cause of Global Warming. Some of the GCM flaws are also exposed by review of climate history as presented graphically from government and other credible sources at http://www.middlebury.net/op-ed/pangburn.html. All data sources are given.

I have always questioned whether present day concentrations of CO2 in air bubbles in ice represent the original concentrations.

If CO2 is more soluble in ice than O2 or N, then clearly CO2 concentrations measured today are not equal to concentrations at the time of formation of the bubbles

Science may be able to accurately estimate original concentrations based upon relative solubilities but given the wide range of solubility of CO2 in particular, with varying (and not accurately known) local temperatures, then this would be prone to error - as would any computer model containing estimates of constants.

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