At the beginning of the last millennium, Vikings were raising cattle in Greenland. It was called the Medieval Warm Period, that two- or three-centuries long block of time that the IPCC wanted to "get rid of" as stated in their leaked e-mails. By the way, it's still to cold to raise cattle in Greenland. I hear there are some sheep farms, but no cattle.
Think of Greenland as a giant hat.