Email 1661, Mar 2006, Ed Cook: We know that trees don't function as thermometers for the period where we have thermometer data, but let's just assume that they worked as thermometers for all periods before that

Email 1661

Obviously I have a vested interest in seeing that tree rings are treated fairly, but I am quite open to the science pointing the way with regards to how the divergence issue affects the use of tree rings as records of past temperature. If someone can show that divergence has happened in the past in a large-scale sense as that for the 20th century, I will be happy to look at the evidence. Otherwise, I think we should err on the side of "no past divergence".