Here’s a beautiful picture of a foxtail pine from the MWP, illustrating eloquently the change in treelines:
Original Caption: A dead trunk above current treeline from a foxtail pine that lived about 1000 years ago near Bighorn Plateau in Sequoia National Park.
This is taken from an article here by Andrew Bunn. Bunn has written a terrific article on stripbark trees, cited in our E&E article. (He also posts occasionally on the R-help line.) I mentioned in connection with the Polar Urals that the need for an altitude adjustment seems pretty obvious for tree rings, if there are material changes in altitude. I’ve seen some very important references to changes in bristlecone pine altitude (with a dramatic lowering since the MWP). If the effect went the other way, you can be sure that the Hockey Team would adjust like crazy for it.