So I looked it up on Wikipedia, for people quote from here.
Here is an extract.
Age.[7] Interpretation of ice core data suggests that between 800 and 1300 AD the regions around the fjords of southern Greenland experienced a mild climate, with trees and herbaceous plants growing and livestock being farmed. What is verifiable is that the ice cores indicate Greenland has experienced dramatic temperature shifts many times over the past 100,000 years - which makes it possible to say that areas of Greenland may have been much warmer during the medieval period than they are now and that the ice sheet contracted significantly.[8]
And that is before the Industrial era of developed countrys that is currently being blamed for man made global warming.
