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Friday, April 19, 2013

More Proxy Stuff

Back to the Tierney et al Lake Tanganyika reconstructions.  The low frequency in blue with a high frequency, 1500 year tail used to show how "unprecedented" temperatures today are relative to the past. 

The Lake Tanganyika reconstructions are important in my opinion because they should not suffer some of the more complicated issues of "critter" drift.  For the deep ocean proxies, relatively minor variations in ocean currents can cause huge swings in the estimated SST.  If the uncertainty in the Lake Tanganyika reconstructions is properly considered, it should provide one of the more stable Paleo "reference" points. 

My plot is left to right while the Marcott et al 2013 version used by Nick Stokes is right to left, but you should be able to notice this subtle difference;
In the version I downloaded from NOAA Paleo, the twin peaks top out at about 2C degrees above the mean.  In the Stokes version, the later peak is about 1.8C above the downward shifted mean and the ~11000ka BP peak is nearly 4 C degrees above the shifted mean.  I would tend question whatever "novel" method Marcott uses if the proxies get selectively scaled. 

This proxy stuff really shouldn't be as hard as these "experts" make it out to be.  There is data, uncertainty and weighting, but it should all start with just looking at the bleeding data first.

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