current Arctic warming is compared to the natural variability of the last thousand years," said Marchitto, also an associate professor in CU-Boulder's geological sciences department. "We found that modern Fram Strait water temperatures are well outside the natural bounds." It was warmer than present in Greenland during the MWP according to Kobashi et al. 2011 (includes Jason Box). Around 1100 AD it was warmer than present for most of a 50 year period and then around ~700 AD it was significantly warmer than present for ~100 years. (More than 1C for most and 2C warmer for a short period) (Nearly the difference from present to the LIA in Greenland). The paper refers to snow temperature of Greenland only, not to the global average temperature. Unofortunately, the period you mention ~700 AD is outside the range generally considered to the be the Medieval Warm Period - that is taken to be 950-1150, a period when the snow temperature is shown to be about the same as the present. Viking settlement in Greenland began only after 900 AD, so these may not have had the advantage of a warmer climate usually assumed, and the "MWP" kinda vanishes. In fact, before the Vikings, Greenland had been settled by an Inuit-related people known as the Dorset people. Perhaps they left because of climate conditions, but that does not sound right for a Inuit-related better-adapted people than the Vikings. The paper is interesting and should repay further comparative study. However, it raises as many questions