1) It's not clear how to derive a signal from that evidence. Is a thicker tree ring evidence of a hotter, wetter climate, or a "happy medium" temperature? 2) S

1) It's not clear how to derive a signal from that evidence. Is a thicker tree ring evidence of a hotter, wetter climate, or a "happy medium" temperature? 2) Such a record of tree rings, if it could produce any temperature signal whatsoever, would be a relative signal: Each year would be calculated in relation to other years on the same timeline for the same tree. How you could map that signal to modern temperature observations in any meaningful way? Personally if you're talking about a global temperature estimate, I would only trust the gold standard: Satellite observations starting in 1978.