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This is the PDF linked from the foornote in the wikipedia article:

If I understand the issue correctly, Oetscher is claiming that diffusion of gas in firn explains the 83-year shift.

We have met the enemy, and he is us — Pogo
by Migeru (migeru at eurotrib dot com) on Mon Jan 28th, 2008 at 11:47:15 AM EST
[ Parent ]
This is Jaworowski's Key Claim.

Zbigniew Jaworowski on CO2 measurements

The data from shallow ice cores, such as those from Siple, Antarctica[5, 6], are widely used as a proof of man-made increase of CO2 content in the global atmosphere, notably by IPCC[7]. These data show a clear inverse correlation between the decreasing CO2 concentrations, and the load-pressure increasing with depth (Figure 1 A) . The problem with Siple data (and with other shallow cores) is that the CO2 concentration found in pre-industrial ice from a depth of 68 meters (i.e. above the depth of clathrate formation) was "too high". This ice was deposited in 1890 AD, and the CO2 concentration was 328 ppmv, not about 290 ppmv, as needed by man-made warming hypothesis. The CO2 atmospheric concentration of about 328 ppmv was measured at Mauna Loa, Hawaii as later as in 1973[8], i.e. 83 years after the ice was deposited at Siple.

An ad hoc assumption, not supported by any factual evidence[3, 9], solved the problem: the average age of air was arbitrary decreed to be exactly 83 years younger than the ice in which it was trapped. The "corrected" ice data were then smoothly aligned with the Mauna Loa record (Figure 1 B) , and reproduced in countless publications as a famous "Siple curve". Only thirteen years later, in 1993, glaciologists attempted to prove experimentally the "age assumption"[10], but they failed[9].

...

3. Jaworowski, Z., T.V. Segalstad, and N. Ono, Do glaciers tell a true atmospheric CO2 story? The Science of the Total Environment, 1992. 114: p. 227-284.

...

  1. Jaworowski, Z., Ancient atmosphere - validity of ice records. Environ. Sci. & Pollut. Res., 1994. 1(3): p. 161-171.

  2. Schwander, J., et al., The age of the air in the firn and the ice at Summit, Greenland. J. Geophys. Res., 1993. 98(D2): p. 2831-2838.


We have met the enemy, and he is us — Pogo
by Migeru (migeru at eurotrib dot com) on Mon Jan 28th, 2008 at 11:52:24 AM EST
[ Parent ]
Note the 1994 paper is the one Oeschger's rebuttal refers to.

We have met the enemy, and he is us — Pogo
by Migeru (migeru at eurotrib dot com) on Mon Jan 28th, 2008 at 11:54:44 AM EST
[ Parent ]
Miguel I have to leave now. This is a fascinating issue, we'll have to get back again to it some day.

You might find me At The Edge Of Time.
by Luis de Sousa (luis[dot]a[dot]de[dot]sousa[at]gmail[dot]com) on Mon Jan 28th, 2008 at 12:51:27 PM EST
[ Parent ]
The entire letter by Oescher is transcribed as HTML in the blog Some are Boojums:
Hans Oeschger's letter to ESPR
Jaworowski's article in ESPR is so hard to locate, it wouldn't be too unreasonable to suspect that the journal is not eager now for people to take much notice of it. But it did get noticed by one giant in climate science -- Hans Oeschger.
Prof. Oeschger was the founder of the Division of Climate and Environmental Physics at the Physics Institute of the University of Bern. His name is attached to the Oeschger Counter that enabled Carbon-14 dating to be applied to geophysical problems, and to the Dansgaard-Oeschger 1,500 year cycle of slow cooling and abrupt warming observed in sediments and ice cores. He was active and influential in climate science until his death in 1998. His assessment of the Jaworowski article was blunt.


We have met the enemy, and he is us — Pogo
by Migeru (migeru at eurotrib dot com) on Mon Jan 28th, 2008 at 05:27:46 PM EST
[ Parent ]

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