- #1
Andre
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- 74
In some threads around here I have hinted to problems with the use of 'water' isotope ratio's (δ18O, δ2H aka δD) as thermometer of past temperatures. This could become a dense thread, so I'll give the conclusion first:
The isotope ratio's in ice cores and other records of meteoric water are mainly proxies for absolute humidity at the water source.
That's a bummer since the isotopes are used a prominent tool to reconstruct paleo climate. Also it took me years to find this out, while the actual principle is so simple.
No this is not a new theory, it's just testing an existing theory, looking how paleo climatology and hydrography compare to basic meteorology. And actually combining some threads in the first page of this forum also gives this result.
The theorie for using isotopes as temperature proxies is wrapped up in http://courses.washington.edu/proxies/JouzelJGR1997.pdf.
Actually we could also keep it quite simple. The most important sentence in Jouzel et al is (page 46,481):
Cuffy et al 1995 state (page 455):
For the moment I don't think we have to dig deeper, because I have not found any isotope -temperature study that elaborates on cloud temperature. But we have a thread here about that.
To be continued soon
The isotope ratio's in ice cores and other records of meteoric water are mainly proxies for absolute humidity at the water source.
That's a bummer since the isotopes are used a prominent tool to reconstruct paleo climate. Also it took me years to find this out, while the actual principle is so simple.
No this is not a new theory, it's just testing an existing theory, looking how paleo climatology and hydrography compare to basic meteorology. And actually combining some threads in the first page of this forum also gives this result.
The theorie for using isotopes as temperature proxies is wrapped up in http://courses.washington.edu/proxies/JouzelJGR1997.pdf.
Actually we could also keep it quite simple. The most important sentence in Jouzel et al is (page 46,481):
Finally, we should keep in mind that isotope changes record cloud temperature [Cuffey et al., 1995]...
Cuffy et al 1995 state (page 455):
...many factors in addition to local environmental temperature affect isotopic composition. Thes include changes in sea-surface composition and temperature (10), changes in atmospheric circulation (11), changes in cloud temperature, which may be different from changes in surface temperature (12), changes in the seasonality of precipitation (13),...
For the moment I don't think we have to dig deeper, because I have not found any isotope -temperature study that elaborates on cloud temperature. But we have a thread here about that.
To be continued soon