Tree Thermometers, Did You Know That… ?

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Tree Thermometers, Did You Know That… ?
By Ed Caryl

This chart is Figure 1(b) from the Intergovernmental Panel on Climate Change Third Assessment Report, (c) 2001. The Intergovernmental Panel on Climate Change.

Michael Mann’s hockey stick chart Fig 1b of the IPCC TAR

The source of this image is a PDF file that can be downloaded here: IPCC TAR.

Much of the data in Michael Mann’s famous “Hockey Stick” graph is derived from pine tree ring “proxies” for temperature.

  • Did you know that trees do not photosynthesize at night, and during much of the winter, therefore cannot record temperature during these periods?

John Daly was first to point this out in 2000, here, along with many other points casting doubt on the Hockey Stick.

In many plants photosynthesis stops at night and at temperatures below freezing. At low light levels, temperature has little to do with plant growth. Pine trees can photosynthesize in winter, but only down to –4.5°C (Scotts Pine), due to the resin antifreeze content in their needles, but the rate of photosynthesis changes through the winter due to needle loss and day length. Pine trees also reduce their rate of photosynthesis as they age. The time constant of change in photosynthesis to a step change in temperature is 5 days.

So if “treemometers” only work during daylight, at temperatures above –4.5°C, growth varies with light level, needle loss, and age, and has a five-day temperature response time, are trees reliable enough to be used for accurate temperature reconstructions? You’d have to be one heck of a data optimist who happens to be one heck of a future climate-pessimist to believe it.

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6 responses to “Tree Thermometers, Did You Know That… ?”

  1. TinyCO2

    Just never let a proxy scientist measure your temperature 😉

  2. R. de Haan

    Great piece Ed Carl.

    November 20, 2009: The Day “Global Warming” Ended

  3. R. de Haan

    Ed, good of you to refer to the work of the late John Daly.
    I used to visit his site frequently when he was still alive and I think we owe him a lot.
    As one of the first skeptics on the web he performed an incredible job and he took the full brunt of the warmist maniacs who were out to discredit and destroy him. The same goes for Dr. Timothy Ball.

    IMO they are the real skeptic pioneers and they shouldn’t be forgotten.

  4. Steve Koch

    Also, tree ring growth is heavily influenced by the amount of rainfall. Trees do well in summer when there is plenty of rain and suffer in times of drought. Not to mention that when the tree rings in recent years did not give Mann the numbers he wanted, he just tossed them and used heavily massaged thermometer based readings instead.

  5. Sundance

    Not since Moses’ ascent of Mt. Horeb has shrubbery been so important in religious matters. The shrubbery involved in the findings of “one tree” Briffa in many ways mirrors that of Moses. While Briffa’s shrubbery resided in the Urals and didn’t speak to him directly, his shrubbery spoke to him indirectly and it appears one tree in particular spoke louder than all the rest.

    There were also contrasts in the comparison. Moses’ shrub instructed him to lead the Jews to the promised land. Briffa’s shrub told him to lead the climate science community to the promised land (Nobel prizes, fame, research grants, etc.) Whereas Moses’ shrub was not consumed by its flames, Briffa’s shrub warned that man’s CO2 would cause the Earth to be consumed by flames.

    Back to similarities. The story of Moses’ shrub has been derided as fiction by many in modern times. The story of the Briffa’s shrubbery is also being derided as fiction now. True believers in the story of Moses’ encounter with a shrub will not be dissuaded from their religion and true believers in the story of Briffa’s encounter with shrubbery will not be dissuaded from their religion either.

    Back to differences. The believers of the story of Moses’ shrub are not trying to force the rest of the world to believe their religion while the believers in the story of Briffa’s shrub are fanatical about forcing others to believe in their religion. ;*)

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