2011-05-01 20:34:29New hockey stick paper hot off the press
John Cook


Just added this to the database (ha! in your face, Ari and Rob - okay, you're still hundreds of papers ahead of me... okay, never mind):


Eight, millennial-scale proxy reconstructions of temperature of the Northern Hemisphere were compared to instrumentally measured temperatures. The effect of anomalous reduction in sensitivity over the last decades (divergence) in the tree-ring based records was taken into account. Statistical analyses showed that in the extratropical part of the Northern Hemisphere the time period 1988–2008 was the warmest two decades within the last 1000 years and had a probability of more than 0.70. The established exceptional level of current temperature changes over those areas that were the least disturbed by local anthropogenic impact indicates that over the last two decades the climatic system was perturbed by an additional global-scale forcing factor, which had not operated in the past.

Sounds like pretty significant stuff. If anyone would like to do a post about this and need me to email the full paper, let me know.

2011-05-03 03:42:40


Not sure if I'm the one to write this, but it actually could be used as a good discussion piece.  It cuts to the chase of the reconstructions.  

  • Way to correct for divergence
  • The last 2 decades warmist in last 1000 years in 8 of the 9 reconstructions more than .7 probability (Pi - 2 STD).  The other (mcyintyre & mckitrick) last 500 years making it difficult to argue centenial temperature oscillations.
  • " In spite of some discrepancy between our and their results, which may be explained by different temperature reconstructions, those author's data in general suggest that the last two decades was a period of abnormally high temperatures and, hence, an abnormal period for the climatic system. This suggests that at the end of twentieth century the climatic system was additionally perturbed by some new forcing factor on a global scale."

I can't back up the methods used nor have I seen and comments on this study. 

2011-05-03 04:36:49
Dana Nuccitelli

Definitely sounds worth a post.  I think John is our resident hockey stick guy, but also a tad busy.  Maybe someone like Rober Way could take it?

2011-05-03 09:28:14


I'm a bit uncertain about this paper - why do they use Loehle 2007 - it does not seem like a good idea? This is not discussed at all in the paper which they should.

The paper seems a bit amaturish in my opinion. Loehle 2007 is claimed to be global (not extratropical part of the Northern Hemisphere) - in fact Loehle is cherry picked to give the correct message of global mwp.

I would be very careful on this one, even if it has the "right" message.

2011-05-03 09:55:35
Julian Brimelow

I concur with oslo's observations.  Also, the reference to M&M's finding re 15th century temps ("However, the reconstruction of McIntyre and McKitrick (2003) showed that at the beginning of the fifteenth century the climate
was warmer." is a little disconcerting, depsite their cavet. I'm really not sure how to read/interpret this paper.  I'd proceed with caution.

Note, this is not a new HS, it is a statistical analysis of eight reconstructions. Why is Ljungqvist not in there?


2011-05-03 10:03:20


> Why is Ljungqvist not in there?

My thought as well...

Why not use original proxy records and create their own set?

Many mysteries on this paper - a debunk would be more like it ;-)

2011-05-03 19:00:31


the paper has a limited goal, semi-empirically account for the divergence to assess if the MWP was warmer than present or not. M&M is there to show that it's the outlier.
I've never been a fan of the warmest month/year/period so I'm not much thrilled by this paper.