With apologies to the Geico caveman, paleoclimatology isn’t just for grant enabled scientists anymore.
Priceless Climategate email 682: Tom Wigley tells Michael Mann that his son did a tree ring science fair project (using trees behind NCAR) that invalidated the centerpiece of Mann’s work:
‘A few years back, my son Eirik did a tree ring science fair project using trees behind NCAR. He found that widths correlated with both temp and precip. However, temp and precip also correlate. There is much other evidence that it is precip that is the driver, and that the temp/width correlation arises via the temp/precip correlation’
From email 682.txt
h/t to Tom Nelson
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I’ve been troubled by tthe reliance on tree ring data as a temperature proxy since I first heard of Mann’s hockey stick. The truth is that the kid’s experimenta;l conclusions are quite correct – you can’t, without significant supporting evidence from other sources, rely on tree ring data as a temperature proxy. If it means anything, I spent my entire working carreer studying, publishing, and teaching plant phsiology. I have also written several textbooks on the subject. The uptake of water is the driving force for plant cell expansion (i.e., growth) and it is quite plausible that trees may produce larger rings during a cool, wet season than during a warm or hot, dry season. In brief, water is the limiting factor in plant growth, not temperature. Regardless of temperature, the width of the rings is ultimately dependent on the availability of water.
I note that no one has suggested tree ring width as a proxy for CO2 concentration and availability. In thick stands of trees and vegetation, I believe that when the sunlight is brightest, the CO2 levels can fall steeply, absent a strong air flow from elsewhere. Like a cornfield that stops growing at midday for lack of food gas.
Clearly the kid got funding from big oil behind his old man’s back.