David Stockwell has published preliminary results of his new study, applying the methods of Mann et al to the same surface temperature data, but using other associated data.
A graph of Stockwell's results:
As can be seen, this is very strongly similar to the "hockey stick" graph of
What's interesting about Stockwell's results is this: his associated data is not real observational data, but "red noise": "1000 sequences of 2000 random numbers containing red noise generated with a multiple time scale fluctuation approach."
What is "red noise"? Random numbers. Specifically, red noise is a random signal in which the amplitude decreases monotonically as the frequency increases.
Reproduced from Stockwell's initial paper (in submission), here is his conclusion:
The resulting reconstruction is very similar to published reconstructions (e.g. see ), exhibiting a gradual decline in temperatures from an apparent Medieval Warm Period (MWP)), and an anomalous 20th Century warming popularly known as the ’hockey-stick’  Clearly the ’hockey-stick’ pattern is easily produced by selecting those random series that correlate over the period of the calibration temperatures (producing the blade) and revert to randomness elsewhere (producing the handle). The apparent height of the MWP is an function of the arbitrary zero calibration point. Thus all the salient aspects of past climate usually associated with millennial reconstructions are essentially already encoded into the methodology, so that a ’hockey-stick’ shape is inevitable on any data resembling natural LTP series.
[Updated with second graphic, and corrected authors.]