Glaciers and Greenland
The period before the Little Ice Age was in fact preceded by a several hundred-year period with generally warmer-than-average temperature conditions. During this time, Greenland (which was actually green during this warm period) was settled near the end of the 10th century. From 1000-3000 CE, the colony flourished: a cathedral was built, a monastery and a nunnery existed, and more than 3,000 colonist lived on 300 farms. But as the Little Ice Age approached, Weather continually degenerated for the colonists. Harvests failed, settlements to the north were abandoned as the permafrost level rose and glaciers spread south. In fact, today archeological studies of the Greenland colony date graves based on how shallow the coffin was buried because of the increased permafrost level over time.
http://jrscience.wcp.muohio.edu/Weather ... bigen.html