At http://sciencenordic.com/vikings-grew-barley-greenland … at the bottom of a medieval rubbish pit on an abandoned farm on Greenland archaeologists found charred grains of cultivated barley seed. This means the Vikings grew barley – necessary for their beer, but also as a food (made into a bread or a porridge, a staple of the period). This illustrates how warm it must have been in the medieval warm period – as in a cold climate barley could not survive. It seems they must have taken seed corn with them when they sailed across the Atlantic – initially, or as part of supplies and equipment at a later stage in the settlement. The massive glacier at the centre of Greenland must still have been in existence – but there are mountain glaciers in Norway so that was not perhaps seen as anything too extraordinary. Barley grows in cool temperatures. It doesn't like it too cold – but it doesn't like it too hot. However, there were no fields of nodding barley seed heads. Instead, barley was grown in comparitively small and sheltered enclosures, limited by the labour available to irrigate the growing seed heads.
It should be noted that modern day Greenland has farmers – mainly keeping sheep. They appear to have settled in exactly the same locations as the Vikings a 1000 years ago. It was probably a little warmer than today and the southern tip of Greenland may well have green and fairly pleasant. Something attracted Eric the Red – and he christened it green – land (which means vegetation). According to the holy bible of CAGW politikking, and the so called 'hockey stick' graph, the medieval warm period was a fiction and those words were screamed in rants that detracted from the actually of Viking settlers there, and denying all climate science prior to 1998. Ah well, at least Hubert Lamb, a real climate scientist, knew better.