Climategate debunked? Mann and Briffa explaining the “Mick’s Nature Trick”
Published 01st December 2009 - 20 comments - 5316 views -
If you use only tree-rings, the "present global warming" is only 0.1°C warmer than Medieval Warm Period. Because above certain level of temperatures the tree-rings do not respond any more. But such slight warming was not enough to raise "global warming hysteria". So they improved it by adding the black line (instrumental records from our thermometers)... If we had MWP instrumental records, the medieval temperatures would also be much higher in the graph.
Was it warmer in Middle Ages than today? Or is our warming alarming? Is IPCC hiding the existence of MWP from us? Let us hear, how Mann et al. explain the famous "hide the decline" line from the leaked CRU e-mails (the Climategate affair from autumn 2009):
HACKED CRU E-MAIL:
An excerpt from one November 1999 email authored by the head of the CRU, Phil Jones, reads, "I've just completed Mike's Nature [the science journal] trick of adding in the real temps to each series for the last 20 years (ie, from 1981 onwards) and from 1961 for Keith's to hide the decline."
Mick refers to Michael Mann, the author of Hockeystick graph.
RealClimate: "The paper in question is the Mann, Bradley and Hughes (1998) Nature paper on the original multiproxy temperature reconstruction....Note that the ‘hide the decline’ comment was made in 1999 – 10 years ago, and has no connection whatsoever to more recent instrumental records."
RealClimate: "As for the 'decline', it is well known that Keith Briffa's maximum latewood tree ring density proxy diverges from the temperature records after 1960 (this is more commonly known as the "divergence problem" - see e.g. the recent discussion in this paper) and has been discussed in the literature since Briffa et al in Nature in 1998 (Nature, 391, 678-682)."
- Tree-rings react very weakly to increasing temperatures. It seems that upon reaching certain level of temperatures, the trees react weakly to any further temperature increase.
- Tree-rings do not reflect the late 20th century warming.
- Hence it is logical to assume, that they do not reflect the Medieval Warm Period either.
- If you use only tree-rings you get this traph: no MWP but also no Global Warming in the late 20th century.
The divergence problem is well known and published. So it is odd, that someone still takes hockeystick seriously.
WHY USE TRICKS?
RealClimate: "The 'trick' is just to plot the instrumental records along with reconstruction so that the context of the recent warming is clear."
- If you do not use this trick, tree-rings graph will show no warming in MWP but also no warming in the 20th century
- But if you use this trick, you will get a hockey-stick: no warming in MWP, but big warming in the 20th century.... Miracle... Suddenly we can see tremendous gigantic unprecedented AGW. Alarm!
MANN AND BRIFFA RECOMMEND NOT TO USE HOCKEYSTICK GRAPH
RealClimate: "Those authors have always recommended not using the post-1960 part of their reconstruction, and so while 'hiding' is probably a poor choice of words (since it is 'hidden' in plain sight), not using the data in the plot is completely appropriate, as is further research to understand why this happens."
- Birffa used "Mick's Nature trick" (invented by Mann in 1998, when he invented the Hockeystick graph)
- Briffa openly admitted, that thus acquired results are misleading and should not be used.
- My conclusion is, that Hockeystick is also misleading and should not be used
- Anything that uses Mick's Nature Trick is misleading and should be avoided
WHAT HAPPENS IF YOU DO NOT USE "MICK'S NATURE TRICK"
A) If you use tree-rings and no tricks, you get an almost flat line, with little curvature. No big "global warming".
B) If you use other than tree-ring data, you get the graph, which was in 1990 IPCC report (FAR): a big MWP (higher temperatures than now or same temperatures) and big LIA. This is why independent research confirms, thata MWP existed and was as warm as today, maybe warmer (see e.g. peer-reviewed literature at http://www.co2science.org/data/mwp/mwpp.php)
Moberg, A., Sonechkin, D.M., Holmgren, K., Datsenko, N.M. and Karlen, W. 2005. Highly variable Northern Hemisphere temperatures reconstructed from low- and high-resolution proxy data. Nature 433: 613-617.
Michael Mann and his bunch should be silent and stop their feeble excuses. The more they try to "explain" their frauds, the more they damage their reputation. Thanks to Mann's above confession it is clear now. Unprecedented Global Warming was really Mann-made.
Since our temperatures are not unique or alarming, there is no reason for climatic hysteria or hurried "mitigation measures". We have already experienced such temperatures in Middle Ages and we were just fine.
1) The CRU hack:Context (23 Nov 2009). RealClimate Website of Michael Mann et al. <http://www.realclimate.org/index.php/archives/2009/11/the-cru-hack-context/> Michael Mann explaining in his own words.
2) A blog discussing the divergence problem in detail clearly: http://jhammerton.wordpress.com/2009/11/29/climategate-on-the-mikes-nature-trick-email/
3) CRU climate data already 95% available. CRU website (28 Nov 2009) <http://www.uea.ac.uk/mac/comm/media/press/2009/nov/homepagenews/CRUupdate> Here you can see a graph of what happens if you do/don't use Mick's Nature trick.
4) Craig Idso et al. MWP Project <http://www.co2science.org/data/mwp/mwpp.php> Listing of peer-review research documenting ther MWP period. This is real science, not IPCC.
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