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Andre
Joined: 21 Jul 2007
Posts: 298
Location: Germany - The Nederlands
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 Posted: Fri Jul 27, 2007 8:27 am Post subject: Exhibit #3, The Younger Dryas and South Greenland |
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The objective of the "Exhibit-#n-The-Younger-Dryas-and .......,"-threads is to investigate for ourselfs what evidence is available to judge about the alleged cold conditions of the Younger Dryas.
High in Central Greenland the ice cores seem to tell us something about climate, like this:
There are good reasons to assume that the middle graph of oxygen isotopes represents temperatures, yet it is a hypothesis, which is backed up by other hypotheses.
But there are also problems, the large difference with Antarctic cores:
It appeared that thas was some pretty assymmetric warming going on between the hemispheres, or? Are those big temperature differences really possible or is it something else?
Therefore we investigate other geologic records to see what's going on. For that we are interested in the closest possible proxy to the Greenland ice cores and we find those in South Greenland:
Anomalously mild Younger Dryas summer conditions in southern Greenland.
| Quote: | ABSTRACT
The first late-glacial lake sediments found in Greenland were analyzed with respect to a variety of environmental variables. The analyzed sequence covers the time span between 14 400 and 10 500 calendar yr B.P., and the data imply that the conditions in southernmost Greenland during the Younger Dryas stadial, 12 800–11 550 calendar yr B.P., were characterized by an arid climate with cold winters and mild summers,p receded by humid conditions with cooler summers. Climate models imply that such an anomaly may be explained by local climatic phenomenon caused by high insolation and Fohn effects. It shows that regional and local variations of Younger Dryas summer conditions in the North Atlantic region may have been larger than previously found from proxy data and modeling experiments. |
So the authors think that they have found an anomaly and get to the models to see if they can unexplain it with all kind of constructions. But if you find yourself back constantly explaining anomalies, doesn't that mean that you don't have a theory anymore?:
| Quote: | Chapter VIII
C: In responding to these crises, scientists generally do not renounce the paradigm that has led them into crisis:
-3: They devise numerous articulations and ad hoc modifications of their theory in order to eliminate any apparent conflict. |
So how was it established that isotopes were temperatures in the first place?
Jouzel, J. et al 1997. Validity of the Temperature Reconstruction from Water Isotopes in Ice Cores; Journal of Geophysical Research Vol 102, No C12 pp 26,471-26,487, November 30
Notice that they had to make a choice here. Trust reality or trust models. If you don't trust reality, you make the wrong choice. This is the place and the time where palaeclimatology went astray.
So if both Jouzel et al and Björck et al would have compared their results without models they would have found out that there were indeed large seasonal precipitation differences and that both proxies were telling the same thing. Cool wet summers in the Bolling Allerod and warm dry summers in the Younger Dryas.[/i]
See also
The Younger Dryas exhibits
Exhibit #1, The Younger Dryas and the Meerfelder maar
Exhibit #2, The Younger Dryas and Mediterranean region
Exhibit #3, The Younger Dryas and South greenland
Exhibit #4, The Younger Dryas and Glaciation
Exhibit #5, The Younger Dryas and the Mystery interval
Exhibit #6, The Younger Dryas and North America
Exhibit #7, The start of the Younger Dryas
Exhibit #8, The Younger Dryas and the Siberian Steppes
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