 The Medieval Warm Period ended sometime towards the end of the 13th century, bringing the "Little Ice Age" and harsher winters with reduced harvests.In Northern Europe, new technological innovations such as the heavy plough and the three-field system were not as effective in clearing new fields for harvest as they were in the Mediterranean because the north had poor, clay-like soil.Food shortages and rapidly inflating prices were a fact of life for as much as a century before the plague.