What Happened to the Vikings in Greenland?
One of the great mysteries of North Atlantic archaeology has been the fate of the Vikings who colonized Greenland in the 980s, and lived there for nearly 500 years—before vanishing. There is no written or even oral history to explain their disappearance, but a new study of sea-level rise along the coast of medieval Greenland suggests that the dramatically rising sea would have been a factor. Their farms, scattered along the fringe of green, arable land of coastal Greenland, experienced a sea-level rise of as much as 3.3 meters, or nearly 11 feet, during the time they lived there. Understanding what happened may illuminate some of the threats from rising seas in a changing twenty-first century climate.
“The pervasive flooding and sea-level rise” would have had a large impact on these farms, says doctoral student Marisa Borreggine, “because the topography of southern Greenland is really dramatic, with glacially carved fjords, and the Viking settlements were all pretty close to the coast.” Borreggine and her coauthors model this substantial regional flooding in their study, “Sea-level rise in Southwest Greenland as a contributor to Viking abandonment,” published April 17 in the Proceedings of the National Academy of Sciences.
Greenland is frequently in the news today because its ice sheet is rapidly melting, contributing to rising seas around the globe. The massive glacier’s demise raises global average sea level in three ways:
- the meltwater increases the volume of the ocean;
- the Earth’s crust rebounds as the glacier’s weight diminishes, displacing the surrounding sea; and
- the gravitational effect of the glacier’s immense mass ebbs, causing the sea-level to fall near Greenland, and to rise in places more than 2,000 kilometers distant.
These effects have been deeply explored in the lab of Baird professor of science Jerry Mitrovica, Borreggine’s adviser and the senior author of the new paper. Last fall, one of Mitrovica’s former students led a study that identified for the first time the fingerprints of Greenland’s melting ice sheet in rising global seas today.
Although the causes of the localized sea-level rise in medieval Greenland are the opposite of the forces causing globally rising seas today, the work nevertheless provides a preview of what coastal communities might expect in the centuries ahead as a consequence of climate change, because the impacts are analogous.
The first of the Greenland settlers began arriving in the 980s from Iceland, which had been colonized about a century earlier. They arrived at the tail end of the medieval warm period, built houses of sod and stone, and began farming and raising animals. At the time, Greenland was uninhabited (Inuit peoples have lived there for at least 4,500 years, but appear to have abandoned the island prior to the Viking arrival, returning a few centuries later, perhaps leading to intercultural conflict). The Vikings hunted walrus seasonally in the north, selling the tusks to traders from Europe, where the ivory was in great demand. This lucrative trade maintained a steady exchange of goods and information between Europe and the remote outpost.
Borreggine’s study focused on the Eastern settlement, which included about 500 farms situated at the southernmost tip of the island. The farms were built about 4 kilometers from each other, but not very far from the margins of the ice sheet that covers most of the island. (A study of the Western Settlement, located nearer the hunting grounds in the north, says Borreggine, found that Vikings farms there were as close as two to five kilometers from the forward edges of the ice.)
Around the year 1250, with the advent of the Little Ice Age, the climate began deteriorating rapidly. With dropping temperatures, the growing season would have shortened, increasing the need for animal fodder during the lengthening off-season. The increasing mass of the ice sheet led to two critical changes in the local environment. First, the sheer weight of the glacier deformed the Earth’s crust, causing the land beneath to sink. At the same time, the glacier’s growing mass exerted an increasing gravitational pull on the nearby ocean, raising the sea-level locally. Fully 204 square kilometers of the Eastern Settlement, Borreggine and her colleagues found, flooded by the latter stages of the Viking occupation. About 60 percent of the farms were within 500 meters of the flooding, and about three quarters of them were within 1,000 meters. With a wall of ice and rock at their backs, and the grasslands before them being gradually swallowed by the sea, the farmers’ marginal existence would have become increasingly tenuous.
The encroaching sea was not the only challenge they faced, Borreggine emphasizes. “In terms of how the Vikings were impacted by the deteriorating conditions, it’s important to realize that they did try to adapt.” As farmers, “They weren’t necessarily relying on marine resources when they arrived. But archaeological research has shown that they did transition from a more land-based diet to one more marine-based throughout their occupation.” Drought may have played a role, and the Vikings were “also experiencing a lot of social and political and economic struggles.” The discovery of other sources of ivory in places like India, for instance, may have contributed to the Greenlanders’ growing isolation. “So, sea level rise is an important factor in the conditions that they were experiencing during their occupation,” Borreggine continues, “but it’s one of many factors that made Viking life difficult in the Eastern Settlement.”
The last written record of Viking life in the Eastern Settlement was of a wedding at Hvalsey Church in 1408, when a local woman named Sigrid married the captain of a visiting ship from Iceland, and returned home with him. Nothing further was heard from Greenland thereafter, and when regular contact with Europe was reestablished in 1721, no sign remained of the settlers’ fate.
Although the ocean has since retreated (as the ice sheet thins today and the land rebounds), says Borreggine, there are still some Viking sites across Western Greenland that are underwater. “It would be really interesting to be able to date all of the settlements,” beginning at the coast and ranging inland, “to see if there was an orderly retreat,” as some archaeologists have theorized. “That would support the idea that they were slowly trying to adapt as best as they could” to a rising sea.