The truth at last

" wrote in
ups.com:

On Mar 13, 4:17 pm, Scott Seidman wrote:
Ken Fortenberry wrote in
news:wcDJh.7140 :

I don't know, but if the historical, all-time high before the
industrial age is ~300 ppm and there is now 379 ppm (and growing)
I'd venture a wild guess and say some of it anyway. Maybe one of
these days we can talk the CO2 molecules into wearing little name
tags while we count them so we can tell "natural" from "human". ;-)

I can't find any reviews of the physics underlying the ice core data,
but the idea that we can melt ice and "know" the CO2 history of the
planet grates on me.

Can anyone in the know tell me for certain that there wouldn't be
Fickian diffusion of the gas throughout the core over the course of
hundreds of thousands of years. Even very slow diffusion adds up,
and it will smooth out the bumps in the CO2 record, flattening out
highs and lows.

I honestly don't know the answer, but it certainly is one of the
things I'd ask about if I were refereeing. I'd almost guarantee that
the climatologists who wrote the original Nature paper (cited more
than 1,200 times!) don't know, either, and neither would the
climatologists solicited for peer review.

--
Scott
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I've been looking for reviews of that too. Let me know if you find
it,
I haven't had any luck.
- Ken



Just in case anyone else wants to sit down with google scholar, the
original article is

Nature 399, 429-436 (3 June 1999) | doi:10.1038/20859; Received 20
January 1999; Accepted 14 April 1999
Climate and atmospheric history of the past 420,000 years from the Vostok
ice core, Antarctica

J. R. Petit1, J. Jouzel2, D. Raynaud1, N. I. Barkov3, J.-M. Barnola1, I.
Basile1, M. Bender4, J. Chappellaz1, M. Davis5, G. Delaygue2, M.
Delmotte1, V. M. Kotlyakov6, M. Legrand1, V. Y. Lipenkov3, C. Lorius1, L.
PÉpin1,1, C. Ritz1, E. Saltzman5 and M. Stievenard2

I'm zeroing in on some of the other issues:

# CRAIG, H, GRAVITATIONAL SEPARATION OF GASES AND ISOTOPES IN POLAR ICE
CAPS, SCIENCE 242: 1675 (1988).[Abstract/Free Full Text]

# RAYNAUD, D, THE ICE RECORD OF GREENHOUSE GASES, SCIENCE 259: 926
(1993).

# RAYNAUD, D, SCIENCE 260: 1411 (1993).[Free Full Text]

# SCHWANDER, J, THE AGE OF THE AIR IN THE FIRN AND THE ICE AT SUMMIT,
GREENLAND, JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES 98: 2831 (1993).



I just printed out Proc. Natl. Acad. Sci. USA
Vol. 94, pp. 8343–8349, August 1997
Colloquium Paper
This paper was presented at a colloquium entitled ‘‘Carbon Dioxide and
Climate Change,’’ organized by Charles D.
Keeling, held November 13–15, 1995, at the National Academy of Sciences,
Irvine, CA.
Gases in ice cores
MICHAEL BENDER*, TODD SOWERS†, AND EDWARD BROOK*‡

This has a section on "The Physics of Gases in Glaciers" I must admit I
thought gases had two s's!
Long section, but:
"The diffusivity of an element or compound decreases with
increasing mass and increasing atomic or molecular diameter.
Thus each element or compound diffuses at a different rate,
and each isotope of a compound diffuses at a different rate. In
consequence, the covariation between the composition of one
gas and another (e.g., CO2 and CH4) in firn is different from
their historical covariation in air. The isotopic composition of
a gas (e.g., CO2) in firn air also varies with the concentration
of that gas in a way that is different from the historical
relationship. The concentrations of gases and isotopes that
diffuse most rapidly will be closest to their current atmospheric
concentrations. Because light isotopes diffuse more rapidly,
the concentration of a gas in firn air will be more depleted in
heavy isotopes than was the atmosphere at the time it had the
same concentration as a firn air sample. Differential diffusivity
is a first-order effect that must be taken into account when
interpreting data on the concentration and isotopic composition
of gases in firn air and ice cores (7)."

What it seems to come down to is that there's a relatively complex
inverse model of all this stuff that needs to be applied. As inverse
models are often ill-posed, of course, it's not clear to me that the
pristine state of the atmosphere can be recovered.




--
Scott
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