Epic sea level rise drove Vikings out of Greenland

The Vikings are remembered as fierce fighters, but even these mighty warriors were no match for climate change. Scientists recently found that ice sheet growth and sea level rise led to massive coastal flooding that inundated Norse farms and ultimately drove the Vikings out of Greenland in the 15th century.

The Vikings first established a foothold in southern Greenland around A.D. 985 with the arrival of Erik Thorvaldsson, also known as "Erik the Red," a Norwegian-born explorer who sailed to Greenland after being exiled from Iceland. Other Viking settlers soon followed, forming communities in Eystribyggð (Eastern Settlement) and Vestribyggð (Western Settlement) that thrived for centuries. (At the time of the Vikings' arrival, Greenland was already inhabited by people of the Dorset Culture, an Indigenous group that preceded the arrival of the Inuit people in the Arctic, according to the University of California Riverside).

Around the 15th century, signs of Norse habitation in the region vanished from the archaeological record. Researchers previously suggested that factors such as climate change and economic shifts likely led the Vikings to abandon Greenland. Now, new findings show that rising seas played a key role, by submerging miles of coastline, according to data presented Wednesday (Dec. 15) at the annual conference of the American Geophysical Union (AGU), held this week in New Orleans and online. 

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Between the 14th and 19th centuries, Europe and North America experienced a period of significantly cooler temperatures, known as the Little Ice Age. Under these chilly conditions, the Greenland Ice Sheet — a vast blanket of ice covering most of Greenland — would have become even bigger, Marisa Julia Borreggine, a doctoral candidate in the Department of Earth and Planetary Sciences at Harvard University, said in a presentation at the AGU conference. 

As the ice sheet advanced, its increasing heaviness weighed down the substrate underneath, making coastal areas more prone to flooding, Borreggine said. At the same time, the increased gravitational attraction between the expanding ice sheet and large masses of sea ice pushed more seawater over Greenland's coast. These two processes could have driven widespread flooding along the coastline — "exactly where the Vikings were settled," Borreggine said. 

The scientists tested their hypothesis by modeling estimated ice growth in southwestern Greenland over the 400-year period of Norse occupation and adding those calculations to a model showing sea level rise during that time. Then, they analyzed maps of known Viking sites to see how their findings lined up with archaeological evidence marking the end of a Viking presence in Greenland. 

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Their models showed that from about 1000 to 1400, rising seas around Greenland would have flooded Viking settlements by as much as 16 feet (5 meters), affecting about 54 square miles (140 square kilometers) of coastal land, Borreggine said. This flooding would have submerged land that the Vikings used for farming and as grazing pastures for their cattle, according to the models.

However, sea level rise was probably not the only reason the Vikings left Greenland. Other types of challenges can cause even long-standing communities to collapse, and a perfect storm of external pressures — such as climate change, social unrest and resource depletion — may have spurred the Vikings to abandon their settlements for good, Borreggine said. 

"A combination of climate and environmental change, the shifting resource landscape, the flux of supply and demand of exclusive products for the foreign market, and interactions with Inuit in the North all could have contributed to this out-migration," she said. "Likely a combination of these factors led to the Norse migration out of Greenland and further west."

Originally published on Live Science.