Multiple contradictions in the same graphic perhaps not the best way to prove anything. If they used the same graph to show the Hockey Stick (1400 to 1980) as they do to show the Medieval Warm period (800 to 2000) then the Hockey Stick disappears or is made irrelevant. And no, they are wrong on the world wide nature of the Medieval Warm period. This view reflects old outdated knowledge, the global warming debate has prompted renewed research (and translation of older results into english) that show it was a worldwide event.