[Tenacious 1]

You seem to be in the know. Can you explain the process in which “tree ring data” is converted into temperature data?

From what little I know, they can measure the growth and health of a tree which tells something about the rainfall or dormacy of the tree. But do you know how they calculate to a degree what the temp was for a certain time period?

I could use some knowledge here.

[andy58-in-nh]

To the extent that I understand the science behind the use of tree rings in climate analysis, there is a good deal of controversy involved. Now, I'm not a scientist but a business process analyst, which means I understand how statistics work - as well as how they can be abused. That study has led to my interest in climatology (I've also been a weather buff since I was a kid).

There are many things that can affect tree growth (and therefore ring width). Among them are:

• The age of the tree (the rate of growth varies through its life)

• Weather (in addition to temperature, there is also precipitation amounts, wind speed and solar exposure)

• Previous years' growth (many trees tend to naturally alternate growth cycles)

• Atmospheric conditions (particularly variances of CO² concentration at altitude)
  

• Competition (other trees nearby or other plants can rob a particular tree of nutrients or light)

• Parasites (Insects and/or fungi infestation can slow growth)

The standard analytical process seems to involve an attempt to normalize some of the factors, including serial correlations (normal year-over-year deviations) and locational persistency.

There are so many factors at play here and such a large standard deviation derived from statistically significant samples that one begins to understand the desire of researchers to take "shortcuts" - by which I mean making blanket assumptions that reduce variability to a tolerance within which they are comfortable drawing conclusions.

It's only my opinion, but that might not be the best method for drawing conclusions that involve the potential expenditure of trillions of dollars and which might affect billions of lives.