Comments
Another ‘Upside Down Mann’ Paper!
Some scientists never learn. Mann et al have a new paper published in Science, 27th November 2009:
Global Signatures and Dynamical Origins of the Little Ice Age and Medieval Climate Anomaly
Michael E. Mann, Zhihua Zhang, Scott Rutherford, Raymond S. Bradley, Malcolm K. Hughes, Drew Shindell, Caspar Ammann, Greg Faluvegi, Fenbiao Ni
Global temperatures are known to have varied over the past 1500 years, but the spatial patterns have remained poorly defined. We used a global climate proxy network to reconstruct surface temperature patterns over this interval. The Medieval period is found to display warmth that matches or exceeds that of the past decade in some regions, but which falls well below recent levels globally. This period is marked by a tendency for La Niña–like conditions in the tropical Pacific. The coldest temperatures of the Little Ice Age are observed over the interval 1400 to 1700 C.E., with greatest cooling over the extratropical Northern Hemisphere continents. The patterns of temperature change imply dynamical responses of climate to natural radiative forcing changes involving El Niño and the North Atlantic Oscillation–Arctic Oscillation.
Jean S posting on Climate Audit comments:
Seems to me that Mann has re-discovered the Medieval Warm Period.
I had a quick look at the paper, SI, and the code. What seems to be done this time is that the proxy network of Mann et al (2008) is processed with a slightly modified screening of Mann et al (2008), and then the reconstruction is done with a slightly modified RegEM CFR of Mann et al (2007)! Now to answer the question that seems to be on everyone’s lips: yes, Tiljander series are still used as inverted. This can be seen from the positive screening correlation values reported in the file 1209proxynames.xls. In fact, going quickly through the screening code, it seemed to me that they have really “moved on” from the screening employed in Mann et al (2008): only “two-sided test” is used!
This means that if a proxy has a strong inverted correlation to the (two-pick?) local temperature, it gets picked – no matter what the physical interpretation is! Since RegEM doesn’t care about the sign, it is now really so that the sign does not matter to them anymore. Anything goes!
I’m speechless.
November 28th, 2009 at 12:39 am
This Mann made global warming has to stop! is there any way one could find out who reviewed this paper as part of the peer review process? just interested…
November 28th, 2009 at 12:51 am
I wouldn’t trust any paper with Mann’s name on it. Given that the ‘Hockey Team’ has about 43 members – the reviewers could be 2 or 3 of those. I haven’t searched the leaked CRU emails to see if there is any mention of this paper.
November 28th, 2009 at 3:55 am
Just a note – the post is by Jean S, not Steve Mc.
November 28th, 2009 at 5:11 am
Ooops! Now fixed, thanks.
December 5th, 2009 at 9:25 am
One thing strikes me as odd about the graph : “95% uncertainty interval”
Shouldn’t that be 95% confidence interval.
Is this some kind of freudian slip or carefully placed dislaimer in case they ever get procecuted for fraud?