Researchers blame sea-level rise in southwest Greenland for Viking abandonment.

From roughly 985 to 1450, Vikings occupied Greenland, farming and building communities before mysteriously disappearing. A new paper from the Harvard University Department of Earth and Planetary Sciences (EPS) suggests that one factor—the rising sea level—likely played a significant role in their disappearance.

Marisa J. Borreggine, lead author of the paper “Sea-Level Rise in Southwest Greenland as a Contributor to Viking Abandonment,” which was published this week (April 17) in Proceedings of the National Academy of Sciences (PNAS), stated that “there are many theories as to what exactly happened” to drive the Vikings from their settlements in Greenland.

“There’s been a change in the story away from the possibility that the Vikings totally neglected to adjust to the climate and toward contentions that they were confronted with a horde of difficulties, going from social distress to financial strife to policy-centered issues and natural change,” said Borreggine, a doctoral competitor in the Harvard Griffin GSAS in EPS.

“The changing landscape would have been yet another factor that would have posed a challenge to the Viking way of life. Along with these other difficulties,”

 Borreggine, who works in the Mitrovica Group led by Frank B. Baird, Jr. Professor of Science Jerry X. Mitrovica. 

“The shifting landscape would have been yet another obstacle to the Viking way of life.” In addition to these additional challenges,” Borreggine, a member of the Mitrovica Group led by Professor of Science Jerry X. Mitrovica and Frank B. Baird, Jr., stated: “To a tipping point before they abandoned the settlement” was probably the result of this.

The flight of these Viking pioneers matched with the start of the period known as the Little Ice Age, which especially affected the North Atlantic. However, in Greenland, a number of factors combined to have the opposite effect, despite the fact that cooling and freezing may appear to lower sea levels.

Borreggine made the observation that since the waters of the North Atlantic “contribute to that new ice volume, intuition might suggest that sea level should go down.” However, a closer look at previously published geomorphological and paleoclimate data as well as the researchers’ modeling of the growth of ice sheets suggested that the opposite occurred in Greenland, specifically at the Eastern Settlement of the Vikings. “As the ice grows or melts, the process of glacial isostatic adjustment causes changes in the gravitational field, the rotation axis, and crustal deformation,” said Borreggine.

“We were able to apply that analysis of non-uniform sea-level change and more accurate sea-level physics to this longstanding archeological question of ‘Why exactly did Vikings abandon the Eastern Settlement?'” This was a first for this kind of research.

The findings of the researchers were striking: other factors, such as the subsidence of Greenland’s land mass, increased the settlement’s vulnerability to flooding in addition to the fact that sea levels were raised by gravity.

Zeroing in on the time of Viking residence from 1000 to 1450, “there’s as of now a foundation pattern of ocean level ascent after Viking appearance in the Eastern Settlement,” they said. “Since a few thousand years ago, it has been rising. But at the same time, there’s a neighborhood impact: “crustal subsidence, or the sinking of land and the gravitational draw of water toward the developing ice sheet.”

Borreggine remarked, “Not only do you have the ground being pushed down, but you also have the sea surface going up.” It is a double blow.”

Researchers discovered that the settlers experienced “up to 3.3 meters of sea-level rise during their occupation” during this time. That’s two to six times faster than sea level rose in the 20th century. Therefore, it was quite intense,” they stated.

This innovative application of sea-level science and archaeological research into the lives of the Vikings who settled in Greenland gave this compelling story more depth. Borreggine mentioned that the group’s analysis revealed that 75% of Viking sites are within 1,000 meters of a floodplain, pointing to the partially submerged warehouse ruins. She noted, “This flooding was all-encompassing.”

The Vikings’ diet also changed as a result of rising sea levels, as their fields became salty or flooded and they switched from their own agricultural products to more marine-based foods. Borreggine asserted that such a shift demonstrates that “they were attempting to adapt to the rising sea level.”

Mitrovica noted that Borreggine “has shown that in addition to the various challenges the Vikings faced as the climate descended into the ice age, they also faced pervasive flooding—an insight that only someone like Marisa, with deep expertise in the sea-level physics, could have had,” and that this paper “…shows the advantages of interdisciplinary research, bringing ideas from one field to another and contributing powerful new insights.”

Assuming the enduring effect of ocean level ascent sounds recognizable in understanding ebb and flow endeavors to moderate environmental change, Borreggine noticed the equals—aand one significant distinction. “The Vikings didn’t actually have a decision,” she said. “They were unable to halt the Little Ice Age. We can work to reduce the effects of climate change. The Vikings got into it.”

More information: Borreggine, Marisa, Sea-level rise in Southwest Greenland as a contributor to Viking abandonment, Proceedings of the National Academy of Sciences (2023). DOI: 10.1073/pnas.2209615120.

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