@farmerman,
Quote:(not like some uneducated hillbilly)
Hillbilly? Hey dumb ass, I is from the big city, NORTH of the Mason Dixon...you is self-admitted to being rural from below the Mason Dixon.
I never discounted using tree rings to guesstimate age (I prefer radio-metric dating thank you)...however when making palaeoclimatic determinations I have a problem.
Several important caveats must be borne in mind when using tree-ring data for palaeoclimate reconstructions. Not least is the intrinsic sampling bias. Tree-ring information is available only in terrestrial regions, so is not available over substantial regions of the globe, and the climate signals contained in tree-ring density or width data reflect a complex biological response to climate forcing. Non-climatic growth trends must be removed from the tree-ring chronology, making it difficult to resolve time-scales longer than the lengths of the constituent chronologies.
Furthermore, the biological response to climate forcing may change over time. There is evidence, for example, that high latitude tree-ring density variations have changed in their response to temperature in recent decades, associated with possible non-climatic factors. In caontrast there has been evidence hpresented that such changes may actually be climatic and result from the effects of increasing winter precipitation on the starting date of the growing season. Carbon dioxide fertilization may also have an influence, particularly on high-elevation drought-sensitive tree species.
Tree growth is not only determined by climate, but is also affected by other, non-climatic factors. Tipically, ring width decreases exponentially with tree age, according to the geometry of an increasing trunk diameter.
Also, for example, growth rate of an individual tree can be greatly enhanced after a neighbour tree is cut.
Thus, climate reconstructions based on tree-ring data are susceptible to several sources of contamination or non-stationarity of response.