As the Greenland ice cap increased in mass during the Little Ice Age, the sea drew near as the ice grew thick,.

While global average sea level fell due to water displacement from oceans to ice caps between 1400 and 1800 AD, the change in local gravity paradoxically raised coastal sea level by as much as 3 meters, inundating coastal farms and settlements.

Sea-level rise in Southwest Greenland as a contributor to Viking abandonment

Marisa Borreggine https://orcid.org/0000-0001-6015-8721 mborreggine@g.harvard.edu, Konstantin Latychev https://orcid.org/0000-0002-9970-9129, Sophie Coulson https://orcid.org/0000-0001-9353-2054, and Richard B. Alley https://orcid.org/0000-0003-1833-0115Authors Info & Affiliations

Edited by Sarah Woodroffe, Durham University, Durham, United Kingdom; received June 10, 2022; accepted

PNAS

Vikings occupied Greenland from 985 CE to the mid-15th century…

Occupation coincided with a transition from the Medieval Warm Period to the Little Ice Age and Southern Greenland Ice Sheet advance. We demonstrate using geophysical modeling that this advance would have (counterintuitively) driven local sea-level rise of ~3 m (when combined with a long-term regional trend) and inundation of 204 km2.

This largely overlooked process led to the abandonment of some sites and pervasive flooding. Progressive sea-level rise impacted the entire settlement and may have acted in tandem with social and environmental factors to drive Viking abandonment of Greenland.

Abstract

The first records of Greenland Vikings date to 985 CE. Archaeological evidence yields insight into how Vikings lived, yet drivers of their disappearance in the 15th century remain enigmatic. Research suggests a combination of environmental and socioeconomic factors, and the climatic shift from the Medieval Warm Period (~900 to 1250 CE) to the Little Ice Age (~1250 to 1900 CE) may have forced them to abandon Greenland. Glacial geomorphology and paleoclimate research suggest that the Southern Greenland Ice Sheet readvanced during Viking occupation, peaking in the Little Ice Age. Counterintuitively, the readvance caused sea-level rise near the ice margin due to increased gravitational attraction toward the ice sheet and crustal subsidence. We estimate ice growth in Southwestern Greenland using geomorphological indicators and lake core data from previous literature. We calculate the effect of ice growth on regional sea level by applying our ice history to a geophysical model of sea level with a resolution of ~1 km across Southwestern Greenland and compare the results to archaeological evidence. The results indicate that sea level rose up to ~3.3 m outside the glaciation zone during Viking settlement, producing shoreline retreat of hundreds of meters. Sea-level rise was progressive and encompassed the entire Eastern Settlement. Moreover, pervasive flooding would have forced abandonment of many coastal sites. These processes likely contributed to the suite of vulnerabilities that led to Viking abandonment of Greenland. Sea-level change thus represents an integral, missing element of the Viking story.