the Air Vent

Because the world needs another opinion

Arctic Deconstruction

Posted by Jeff Id on September 19, 2009

At CA Steve McIntyre has put together a simple script which basically reconstructs the Kaufman Arctic paper from the proxy data. The paper uses CPS methods to rescale 23 proxies before averaging. In my post Kaufman Arctic Proxies you can see the proxies after rescaling by CPS so the weighting of each is reasonably understood. CPS is scaling to standard deviation and a mean of 0 over the calibration range. In Kaufman, the data used was often pre-processed before it reached the paper. For instance in the infamous Yamal hockey stick maker series, the data already has gone through a process similar to Mann08 before incorporation into this paper. Since the data for the process has not been disclosed it cannot be criticized except for the fact that they admit to sorting the tree rings throwing away data which didn’t match temp. How much data was thrown out? We don’t know exactly but by the loss in variance prior to the temp record of the Yamal proxy, it was probably one hell of a lot.
Since we have the already scaled proxies, we can make a curve very similar to the Kaufman one simply by averaging the scaled series.

Arctic recon

Which I think you’ll admit looks fairly similar to this before scaling to DegC and pasting on the dishonest bright red temp curve so common in climatology. A temperature curve which is difficult to replicate so far from the data BTW.

temp-trend[1]I wonder what happens to Figure 1 when we delete the Yamal hockey stick series.

Yamal which is in my previous post looks like this.

Yamal

Yamal is OBVIOUSLY not temperature either but it helps make a nice unprecedented whatever you want. So chuck it in the mash average and your picture of doom becomes as clear as you need to guarantee Copenhagen funding. Anyway, here’s the reconstruction without Yamal. hehe.

Arctic recon noYamal

Woah, look at that. The earth was just a bit warmer at 400 AD than 1998 or 2000, Well rumors of the Roman motorway’s might be true after all. All that by removing a single series. Is a 22 proxy reconstruction less valid than a 23 proxy reconstruction?

I took away one more series just for fun. — the Avam Taimyr tree rings.

`no yamal avam

It’s pretty clear what the reconstruction is made of. A few substitutions with other climatology created proxies by SteveM and the pre 500AD temps are much higher than today.

variation[1]

Check out his post which has links to turnkey code and methods for creating your own Arctic hockey stick. You won’t get climatology’s six figure salary but you will get the same satisfaction of your ability to calculate Arctic temperatures over 2000 years ago to a few tenths of a degree C as the masters themselves.

5 Responses to “Arctic Deconstruction”

  1. Layman Lurker said

    Can you access the Polar Ural proxy data to compare?

  2. The Polar Urals version in my comparison was obtained after quasi-litigation at Sciencemag with Esper for the data in Esper et al 2002. Uniquely among post-2000 Team studies, it used Polar Urals rather than Yamal. (It “adjusted” for this by using 2 bristlecone/foxtail sites a few miles apart.) The Esper reconstruction looks a bit different than other recons because of this. I’ve done posts on this series at CA from time to time.

    Jeff, the underlying Yamal measurement data has never been archived at the ITRDB data bank. I’ve been trying for about 5 years to get the measurement data and never succeeded.

    The Taymir series was used in prior studies and has a big “divergence” problem. The Avam-Taymir series was a new Briffa concoction in Phil Trans 2008. The measurement data for this is not public.

    Which reminds me – the Phil Trans people asked Briffa to provide the measurement data; he provided the Tornetrask-Finland data and asked for some more time for Yamal and Taymir, but it still hasn’t been provided. I’ll try Phil Trans again.

  3. WTH said

    Which I think you’ll admit looks fairly similar to this before scaling to DegC and pasting on the dishonest bright red temp curve so common in climatology. A temperature curve which is difficult to replicate so far from the data BTW.

    The red curve is “based on actual observations” and not the proxy data.
    http://www.ucar.edu/news/releases/2009/arctic2k.jsp

  4. Jeff Id said

    #3 Roman and Hu have been trying to get the same curve from HadCrut and last time I checked weren’t quite getting the same curve.

  5. Jeff Id said

    Steve,

    Thanks for the descriptions of the histories. I’ve got no idea where else anyone would learn these things.

    I love the term “divergence problem”.

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