What I think this means is that a Chinese scientist applied an advanced form of differential calculus to multiple gradients of change in tree rings from 2500 year old tress and published his derivative predictions.
And they prove correct by observation.
Is that correct?
Also found that WUWT has this Story up :
In China, there are no hockey sticks
There are 223 comments.
There always good comments ot WUWT.
Will try to look thru them.
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crosspatch says:
Please keep in mind that tree rings will only show trends in summer temperatures and then it will only show early summer — June and July. The main factors in tree rings are the onset of summer growth and June/July temperatures. The onset of growth is generally constrained by when the snow melts. So a late slow melt can delay initiation of growth for the year and reduce the overall size of the annual ring for that year.
http://academic.engr.arizona.edu/HWR/Brooks/GC572-2004/readings/vaganov-nature-siberia-tree-snow.pdf
But generally, summer temperatures will trend with general climate, though not always. Since 1998 in the continental US, for example, summer temperatures are flat while winter temperatures have been plummeting. Overall annual temperatures are in decline but summer temperatures are flat. Tree rings in North America probably do not show the decline that the instrument record does in annual average temperature observations show (NCDC’s website).
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Kasuha says:
Fourier analysis on time series may be a lot of fun but until physical background of identified cycles is demonstrated it’s not more than just playing with numbers with zero predictive potential.