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scpg02
Joined: 22 Jul 2007
Posts: 221
Location: Sacramento
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 Posted: Wed Oct 31, 2007 2:02 am Post subject: Texel paleothermometer for climate reconstruction perfected |
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Texel paleothermometer for climate reconstruction perfected
8 October 2007
| Quote: | Spanish researcher Carme Huguet further refined the recently developed TEX86 paleothermometer during her doctoral research at the Royal Netherlands Institute for Sea Research (NIOZ). The thermometer measures seawater temperature dependent changes in the cell wall composition of archeabacteria.
Real thermometers have been available since the 17th century. For all periods before this, researchers depend on signs from nature. For such determinations, geochemists resort to molecules from microorganisms whose structure is well preserved in seabeds. The TEX86 index has recently been developed at Royal Netherlands Institute for Sea Research (NIOZ). It is based on temperature-dependent changes in the lipid composition of the cell walls of certain types of archeabacteria. Their cell membranes are composed from special lipids of which the number of carbon rings in the molecule changes with the temperature of the surrounding seawater. These organisms therefore adjust the degree of fluidity of their membranes to the prevailing conditions. Carme Huguet studied several aspects of this in greater detail and made significant improvements to the determination.
With a new detection method the analytical reproducibility of the TEX86 paleothermometer was brought to ±0.3 °C and the deviation in the results measured was reduced to 5% of the average. The TEX86 values for organic material out of the water column and from the uppermost layer of the floor sediment best match the temperature of the uppermost 100 m of seawater. However, the small cells of Crenarchaeota cannot sink to the floor by themselves; they are far too light for that. This is, however, achieved more rapidly if the cells of Crenarchaeota are eaten, for example, by crustaceous zooplankton. Fortunately, the time spent in the gastrointestinal tract of the crustaceans does not harm the molecules. Once they have landed on the sea floor, the preservation of the original fat molecules takes place best in anaerobic sediments. |
http://www.nwo.nl/nwohome.nsf/pages/NWOA_77CJ2S_Eng
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Andre
Joined: 21 Jul 2007
Posts: 298
Location: Germany - The Nederlands
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| Posted: Thu Nov 01, 2007 4:15 pm Post subject: |
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Yes I heard about that, looks promissing. However rigourous research is required to demonstrate that this tex86 stuff is indeed only temperature dependent.
And then again. Sea surface temperature is not a measure for atmospheric temperatures. For instance the extreme hot European summers of 2003 and to a lesser extent, 2004, went hand in hand with remarkable low mid Atlantic sea surface temperatures. It is speculated that the cool ocean prevented the generation of the usual string of low pressure areas which tend to flood western Europe.
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