In his treatise, "Darkness at the Edge of the World" in the March 2017 issue of Smithsonian, environmental specialist Tim Folger focuses on the settlements of Hvalsey, now called Gardar, at the southwestern tip of Greenland, perhaps a hundred miles southeast of Nuuk, an Inuit settlement further up Greenland's west coast.

Settled by Eric the Red sailing from Iceland, this Nordic community was inhabited by at least 1,500 or more people from the tenth to the thirteenth century. Then the Norsemen disappeared. Where? No one knows, but they departed in unison; farmhouse doors were closed, gates latched, and the stones of their large cathedral, with part of the bishop's crosier carved from narwhal bone and his ring remain, although the roof and stained glass are gone.

Today, Gardar is an Inuit settlement, and although Greenland is Danish territory, it is no longer politically connected to Norway. Why did the Norse abandon their settlements? One reason was climate change. In the tenth century, there was a brief warming period (somewhat like today's global warming) that allowed some agriculture, mostly sheep and cattle raising, along the fjords; but farming was not the main cultural endeavor of the Norse Greenlanders. It was ivory hunting, causing near extinction of the Arctic walrus population. The Inuits hunted the animals for food – the Norse for their valuable tusks.