Thompson estimates that some of these ice caps/glaciers (which have ice layers in the Middle Ages) will disappear in the next 20 years. This is our best piece of evidence. I know we don't use them in many of the compilations, but if these areas had layers in the Middle Ages and are disappearing arguments that globally it was warmer in the MWP are shot to pieces.
The Hindu: an interview with Ed Witten
1 hour ago