Holocene Regional Ice History of Southwest Greenland: Driver of Viking Out-Migration?

The first record of Norse Viking sites in Greenland is from 985 A.D. in Eystribygð (the Eastern Settlement) and Vestribygð (the Western Settlement), where Erik the Red and fellow Icelandic migrants settled after his exile. Archaeological evidence, including skeletal remains, churches, and trash heaps (middens), reveals how Vikings lived up until ~1405 A.D. The disappearance of this community from Southwest Greenland in the early 15^th century without any explanation in the written record remains enigmatic. The leading theory suggests that the shift from the climate of the Medieval Warm Period (MWP, ~900-1350 A.D.) to the Little Ice Age (LIA, ~1350-1850 A.D.) forced Viking out-migration when environmental conditions became unfavorable for continued settlement. The effects of the MWP and LIA were geographically variable, however, and this shift may not have impacted this region. Indeed, glacial geomorphology and paleoclimate research suggests the Southwestern Greenland Ice Sheet (GIS) re-advanced through much of the Holocene, reaching peak size during the LIA. We propose that Vikings migrated away from Greenland primarily as a response to regional sea-level rise driven by growth of the southwestern GIS. The re-advance of the GIS would have caused a rise in sea level near the ice margin due to the increased gravitational attraction between the large ice mass and the nearby sea surface, in addition to crustal subsidence. We will test this hypothesis by applying a time-varying spatiotemporal dataset of ice cover in Greenland over the Holocene into a state-of-the-art ice age sea level model and comparing the results to well-dated dated archaeological evidence. This idea is supported by the presence of underwater ruins and drowned beaches, which imply that farming, a primary mode of subsistence at the time, became untenable as the local environmental conditions changed. This study further reveals the potential role of sea level in the disappearance of Norse Vikings from Greenland, alongside environmental and socio-political factors.