Study undercuts idea that 'Medieval Warm Period' was global

A new study questions the popular notion that 10th-century Norse people were able to colonize Greenland because of a period of unusually warm weather. Researchers say the climate was already cold when the Norse arrived -- and that climate thus probably played little role in their mysterious demise some 400 years later. On a larger scale, the study adds to building evidence that the so-called Medieval Warm Period, when Europe enjoyed clement weather, did not necessarily extend to other parts of t