From the Guardian:
New analysis casts doubt on theory that change in climate influenced Vikings to move to Greenland in 985, and posits it would have been relatively cold
The Vikings’ arrival and departure from Greenland was not heavily influenced by the so-called medieval warm period, according to new research that casts doubt that the climatic change was a global phenomenon.
Viking seafarers, led by Erik the Red, are understood to have expanded from Iceland to south-western Greenland around 985. The Norse population grew to about 3,000 to 5,000 settlers, harvesting walrus ivory and raising livestock. But the colonies disappeared by 1460, with the local Inuit population remaining as the only inhabitants before Europeans again arrived in the 1700s.
Previous theories have suggested that a warming climate allowed Norse people to push further north to the frigid expanses of Greenland, before leaving as temperatures dropped again. In what has become known as the medieval warm period, temperatures rose from around 950, with the generally balmier conditions lasting until 1250, before the arrival of what is known as the little ice age.
But new analysis of glaciers in Greenland shows that there was no significant change in their extent during the medieval warm period, suggesting that it remained relatively cold throughout the Viking colonisation of Greenland.
More at the link.