Greenland not green, but was green before climate change a few thousand years ago?
Did not the Norse have vineyards there in the seventh and eighth centuries?
Let's imagine ourselves as Vikings visiting the place during the Medieval Warm Period. If it got warmed up a bit, then you would have glacial runoff water keeping things moist, and the summer days would have been long. That would have made the coasts VERY green.
It was warm enough so that parts of it could be farmed.
https://www.sciencemag.org/news/2016/11/why-did-greenland-s-vikings-disappear