[Mann] Hi Peter, Phil,
No, no, we have to set the record straight!
It was Jerry Mahlman who coined the term ["hockey stick"], and in a complimentary (not insulting) way,
several years ago. I think he used this term to simply point how dramatic the 20th century warming is relative to the longer-term variability.
We have to make sure we don't let the climate change denialists co-opt the term. It should be "re-claimed", so to speak...
[Ed Cook] So, at this stage I would argue that the Medieval Warm Period was probably
a global extra-tropical event, at the very least, with warmth that was
persistent and probably comparable to much of what we have experienced in
the 20th century. However, I would not claim (and nor would Jan) that it
exceeded the warmth of the late 20th century. We simply do not have the
precision or the proxy replication to say that yet. This being said, I do
find the dismissal of the Medieval Warm Period as a meaningful global event
to be grossly premature and probably wrong. Kind of like Mark Twain's
commment that accounts of his death were greatly exaggerated. If, as some
people believe, a degree of symmetry in climate exists between the
hemispheres, which would appear to arise from the tropics, then the
existence of a Medieval Warm Period in the extra-tropics of the NH and SH
argues for its existence in the tropics as well. Only time and an enlarged
suite of proxies that extend into the tropics will tell if this is true.