Nicolás Young of Columbia University’s Lamont-Doherty Earth Observatory is skeptical of the view that the Vikings colonized Greenland during a Big Thaw, since new isotopic analysis dates the maximum advance of glaciers in southwest Greenland to the middle of the erstwhile Medieval Warm Period:
“If the Vikings traveled to Greenland when it was cool, it’s a stretch to say deteriorating climate drove them out.... It’s becoming clearer that the Medieval Warm Period was patchy, not global,”Apart from lousy weather or becoming sick and tired of a diet of seal meat, the Vikings may have quit Greenland because of Inuit attacks, a decline in the walrus ivory trade, overgrazing of icebound pastures by imported cattle, and perhaps most intriguingly, better farming land becoming free for the taking back home in Scandinavia after the population crash of the mid-14th century Black Plague.
http://www.earth.columbia.edu/articles/view/3266
