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Post by hunter on Mar 1, 2010 15:53:33 GMT
naut, I am aware of many studies which tackle the problem of firn. Co-deposition of carbonate laden dusts is one of the problems, fractionation due to gravitation and thermal diffusion are two others. A seminal paper by Huber et al (2006) (attached) may shed some light on how these problems are dealt with in the proxy ice records: You may be interested in this: "CO2 diffusion in polar ice: observations from naturally formed CO2 spikes in the Siple Dome (Antarctica) ice core"Journal of Glaciology, Vol. 54, No. 187, 2008 "ABSTRACT. One common assumption in interpreting ice-core CO2 records is that diffusion in the ice does not affect the concentration profile. However, this assumption remains untested because the extremely small CO2 diffusion coefficient in ice has not been accurately determined in the laboratory. In this study we take advantage of high levels of CO2 associated with refrozen layers in an ice core from Siple Dome, Antarctica, to study CO2 diffusion rates. We use noble gases (Xe/Ar and Kr/Ar), electrical conductivity and Ca2+ ion concentrations to show that substantial CO2 diffusion may occur in ice on timescales of thousands of years. We estimate the permeation coefficient for CO2 in ice is 4 10–21 molm–1 s–1 Pa–1 at –238C in the top 287m (corresponding to 2.74 kyr). Smoothing of the CO2 record by diffusion at this depth/age is one or two orders of magnitude smaller than the smoothing in the firn. However, simulations for depths of 930–950m (60–70 kyr) indicate that smoothing of the CO2 record by diffusion in deep ice is comparable to smoothing in the firn. Other types of diffusion (e.g. via liquid in ice grain boundaries or veins) may also be important but their influence has not been quantified."so does this imply that the ice core record may not be as reliable for proxy purposes as previously thought?
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Post by nautonnier on Mar 1, 2010 17:52:32 GMT
You may be interested in this: "CO2 diffusion in polar ice: observations from naturally formed CO2 spikes in the Siple Dome (Antarctica) ice core"Journal of Glaciology, Vol. 54, No. 187, 2008 "ABSTRACT. One common assumption in interpreting ice-core CO2 records is that diffusion in the ice does not affect the concentration profile. However, this assumption remains untested because the extremely small CO2 diffusion coefficient in ice has not been accurately determined in the laboratory. In this study we take advantage of high levels of CO2 associated with refrozen layers in an ice core from Siple Dome, Antarctica, to study CO2 diffusion rates. We use noble gases (Xe/Ar and Kr/Ar), electrical conductivity and Ca2+ ion concentrations to show that substantial CO2 diffusion may occur in ice on timescales of thousands of years. We estimate the permeation coefficient for CO2 in ice is 4 10–21 molm–1 s–1 Pa–1 at –238C in the top 287m (corresponding to 2.74 kyr). Smoothing of the CO2 record by diffusion at this depth/age is one or two orders of magnitude smaller than the smoothing in the firn. However, simulations for depths of 930–950m (60–70 kyr) indicate that smoothing of the CO2 record by diffusion in deep ice is comparable to smoothing in the firn. Other types of diffusion (e.g. via liquid in ice grain boundaries or veins) may also be important but their influence has not been quantified."so does this imply that the ice core record may not be as reliable for proxy purposes as previously thought? Indeed it does Ice core bubbles are samples from a place on Earth that due to Henry's Law will have very much lower CO 2 concentration in the first place. Then the gases in the trapped air start diffusing into the ice at varying rates. CO 2 apparently diffuses somewhat faster than thought and the contents of the bubbles will start to resemble the varying diffusion rates rather than the initial gas concentrations. As the paper says there is also 'smoothing in the firn'. This is the area where snow gets compacted and freezes into ice and thus represents the most recent years. As with all proxies it appears that the ice record can be 'adjusted' to whatever the modelers want it to be.
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Post by hunter on Mar 1, 2010 20:40:54 GMT
Nautonnier, Do you have a live link to the specific article on ice and CO2. I would like to run it past an acquaintance of mine who has done a lot of ice core work.
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Post by Graeme on Mar 2, 2010 23:00:26 GMT
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Post by nautonnier on Mar 3, 2010 0:01:54 GMT
Nautonnier, Do you have a live link to the specific article on ice and CO2. I would like to run it past an acquaintance of mine who has done a lot of ice core work. A bit difficult to find - I have a copy in my own library but you can find it here www.igsoc.org/journal/54/187/j07j102.pdf
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Post by kiwistonewall on Mar 3, 2010 2:27:58 GMT
Farewell to the Era of Panic (Andrew Bolt) www.heraldsun.com.au/opinion/farewell-to-era-of-panic/story-e6frfhqf-1225836266653BONDI, Sunday morning. The place and the time that our Age of Panic finally died.
And thank God.
You see, last year we completely lost our heads, letting ourselves be convinced that if we weren't killed by swine flu or wiped out by the worst financial catastrophe in our lives, we'd soon fry from global warming.
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Post by magellan on Mar 3, 2010 3:25:47 GMT
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Post by nautonnier on Mar 4, 2010 0:18:22 GMT
" The most famous ice core, the Vostok (Antarctica) core, with air inclusions allegedly representing the global paleoatmospheres over the last 160,000 years, show CO2 levels below 200 ppmv for many tens of thousands of years spanning 30,000 to 110,000 years BP (Barnola et al., 1987). "Most geochemists were convinced that changes such as these could not occur", says Sarmiento (1991) about these low alleged paleoatmospheric CO2 levels. Such low atmospheric CO2 levels below approximately 250 ppmv (McKay et al., 1991) would have led to extinction of certain plant species. This has not been recorded by paleobotanists, showing clearly that the ice core CO2 results are not representative of paleoatmospheres (Jaworowski et al., 1992 b), hence the CO2-ice-core-method and its results must be rejected.""This is a beautiful example of circular logic in action, when such a construction as the evasion factor is used in all carbon cycle models which the IPCC base their anthropogenic CO2-level-rise evidence on. Using the evasion "buffer" factor instead of the chemical Henry's Law will always explain any CO2 level rise as being anthropogenic, because that very idea was the basis for the construction of the evasion "buffer" correction factor.""The short atmospheric CO2 lifetime of 5 years means that CO2 quickly is being taken out of the atmospheric reservoir, and that approximately 135 giga-tonnes (about 18%) of the atmospheric CO2 pool is exchanged each year. This large and fast natural CO2 cycling flux is far more than the approximately 6 giga-tonnes of carbon in the anthropogenic fossil fuel CO2 now contributed annually to the atmosphere, creating so much political turmoil (Segalstad, 1992; 1996)."Its nice to see a restatement of issues where AGW is wanting in a well referenced paper.
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Post by trbixler on Mar 4, 2010 16:01:16 GMT
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Post by hunter on Mar 4, 2010 16:29:13 GMT
Nautonnier, Do you have a live link to the specific article on ice and CO2. I would like to run it past an acquaintance of mine who has done a lot of ice core work. A bit difficult to find - I have a copy in my own library but you can find it here Thank you for making the effort to find this. It is very interesting. I am asking my friend for his opinion on it now. www.igsoc.org/journal/54/187/j07j102.pdf
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Post by magellan on Mar 6, 2010 1:54:42 GMT
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Post by socold on Mar 6, 2010 16:39:03 GMT
"Given the information that the version of the data from the SMHI stations that you hold are likely to differ from the data we hold, SMHI do not want the data to be released on your web site."
Quite clearly Jone's was correct - the SMHI do not want him to hand out their data. They want people to get it right from them.
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Post by trbixler on Mar 6, 2010 17:35:04 GMT
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Post by northsphinx on Mar 6, 2010 17:39:13 GMT
I think You are wrong on this Socold. Jones was asked to show the underlying raw data used by CRU. You see we don't know that. Not even now. Jones claim that he cant because of SMHI. But SMHI do provide the information direct. IF Jones used the SMHI data can he very easily tell us which data he used and tell us from the source used. Jones can very easily state on the CRU site state this without any legal problem. He don't have to provide the data itself from a official CRU site. Just tell us which data used. Not even need to tell us from where to download it because that is an easy task to find out. Just which data used. But since CRU do not even do this BASIC is there a suspicion that the SMHI and the other still to us unknown sources are massaged by You know whom. That IS the bottom line. No one can verify CRU result because no one outside CRU know which raw data are used. And STILL is Jones refuse to tell us which stations date he used. I think I know why.
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Post by nautonnier on Mar 6, 2010 18:04:22 GMT
"Given the information that the version of the data from the SMHI stations that you hold are likely to differ from the data we hold, SMHI do not want the data to be released on your web site." Quite clearly Jone's was correct - the SMHI do not want him to hand out their data. They want people to get it right from them. On the contrary - quite clearly Jones was dissembling From the press release: "All Swedish climate data are available in the public domain. As is demonstrated in the attached correspondence between SMHI (Swedish Meteorological and Hydrological Institute), the UK Met Office and Dr. Jones (the last correspondence dated yesterday March 4), this has been clearly explained to Dr. Jones. What is also clear is that SMHI is reluctant to be connected to data that has undergone “processing” by the East Anglia research unit."
note that the quotes around processing are from the press release - a sign of suspicion from the SMHI I would paraphrase what the Swedish MHI were saying: Do NOT release your "processed" form of the data and misrepresent it as OUR original SMHI raw data. The original _unprocessed_ data is freely and publicly available on our site.As said by NorthSphinx - no-one can trust ANY data coming out of CRU. This is effectively what was said by the Swedes.
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