It disproves man made global warming.
Greenland was much warmer 1000 years ago than it is today, and it stayed warm for 300 years.
At least 6,000 Vikings lived there, grew crops, raised farm animals, and were completely self-sufficient.
It was warmer and then it got a lot colder. Ships stopped coming from the east, and the Vikings did not make the adaptations to cold that the Inuit did which enabled them to continue living there. So they probably want back to where they had come from or sent their children there.