I have no idea when the paper will be on PNAS‘s website, so I thought I would at least point to the ScienceDaily release, Climate Played Big Role in Vikings’ Disappearance from Greenland:
Greenland’s early Viking settlers were subjected to rapidly changing climate. Temperatures plunged several degrees in a span of decades, according to research from Brown University. A reconstruction of 5,600 years of climate history from lakes near the Norse settlement in western Greenland also shows how climate affected the Dorset and Saqqaq cultures…..
The Dorset were the non-European population which preceded the Inuit, and the Saqqaq preceded them. Last year Nature published a paper based on 350,000 SNPs from an ancient Saqqaq male which showed that he was related to modern Siberian peoples, and not to the later Inuit. That’s at least a very clear argument for why we should be very cautious about extrapolating from the genetic patterns of the present back to the past (and to be fair, poking around Google Books it seems that the archaeologists were skeptical of continuity between Saqqaq and Dorset cultures on empirical grounds, even if their theoretical disposition tended toward establishing an evolutionary relationship between the two).
One major issue which always seems to crop up when it comes to climate & culture is that Greenland seems to be the favorite example of a given pet theory for the rise & fall of societies. This is because in Greenland’s case it’s obviously really on the margin of habitability, so a slight shift in the climatic regime may drive a population to extinction. I hope that the paper has a sophisticated accounting of this possibility though, because it is kind of useless to talk about an exogenous factor like climate without also considering the contextual issues. Some historians argue that one reason the Norse of Greenland “died out” is that at the end of the day they didn’t need to adapt, they could evacuate to nearby Iceland, which is what some scholars argued occurred in the early 1400s. The church records clearly indicate that there were marriages between Greenlanders and Icelanders during that period.