Confirmation of Phi’s Reconstruction
Posted by Jeff Id on February 26, 2014
In December last year, reader Phi brought the Briffa MXD data from his 2013 paper to my attention. He showed the following graph of MXD data vs 3 different temperature series. Needless to say, it shows an impressive correlation between trees and temperature:
While Phi made the claim that the trees bear out UAH lower troposphere data over ground temps, I don’t see a single instance of a better fit of tree data to one temp series over another as particularly solid. This is particularly true considering that there are known divergent datasets. Still, it seemed reasonable that Phi had picked out an excellent dataset from the literature to look at. I took my time and downloaded UAH and RSS satellite data, the tree data from Briffa 2013 and found gridded data from CRUTEM4 using the google world map application from this RealClimate™ post. I actually went over to that blog to see if there was anything humorous to tease them about and found a very workable application – so shame on me! Of course, shame on them for having so much to mock but that is for another post.
It took a bit of fiddling with the calibration and filtering but I was able to reproduce a reasonably similar result to Phi. All temperatures presented below are from summer (June to August) averages of the 67.5N 67.5E gridcell closest to the tree data.
What I find amazing is how good a fit this data actually is to historic temps in the recorded period. First, recall that I made this red series above by simply aligning and averaging the data. I did this simple process with the understanding that some of the variance we see in these MXD series is from a statistically significant age related signal, so this series average is not as good a representation of annual tree MXD as it could be. Still, the age correction won’t make much difference and even the oldest portion of the data doesn’t diverge terribly from the black observed temperature curve. One of the main contentions I have with treemometers, besides massive non-linearity, is that the high frequency components and low frequency components aren’t necessarily governed by the same relationship and that those relationships with environmental conditions will change over time. e.g. how does the same tree respond to temperatures in low water vs high water conditions?
Anyway, I looked at lower frequency response in the following plot:
The data from this set is truly fantastic compared to some we have looked at but you can see a large divergence of temperature above tree latewood density in recent years and a similar problem in 1880-1990. We could shift the graph up and down to try for a better fit but it seems pretty obvious that the trees are reacting to other environmental conditions than temperature as years go by. The visual correlation is still amazing though.
While it may be tempting for climate scientists to take this kind of data and paste temperature onto it, calling it a development or something, they may not find the whole reconstruction that exciting. The rest of the data is fairly interesting to those of us skeptical of the general exaggerations pervading the science of global warming doom. Below is the full MXD reconstruction with temperatures to 2006 overlaid.
Like this years RedWings, it seems to be a hockey stick without a blade. I’m still amazed at the quality of the fit to CRUTEM though and have decided to continue this study and take the next step of correcting by the average growth curve and perhaps the pith offset as well.
For completeness, and so the alarmist climate community doesn’t have a heart attack, if we extend CRUTTEM and UAH past the end of the reconstruction to 2012, the graph looks like this:
As always, I intend to make the code available. Unless someone is interested, I will clean it up and post it with my future calibrated reconstruction post.