Human Diet and Subsistence Patterns in Norse Greenland AD C.980—AD c. 1450: Archaeological interpretations

Prolonged drying trend coincident with the demise of Norse settlement in southern Greenland

Declining temperature has been thought to explain the abandonment of Norse settlements, southern Greenland, in the early 15th century, although limited paleoclimate evidence is available from the inner settlement region itself. Here, we reconstruct the temperature and hydroclimate history from lake sediments at a site adjacent to a former Norse farm. We find no substantial temperature changes during the settlement period but rather that the region experienced a persistent drying trend, which peaked in the 16th century. Drier climate would have notably reduced grass production, which was essential for livestock overwintering, and this drying trend is concurrent with a Norse diet shift. We conclude that increasingly dry conditions played a more important role in undermining the viability of the Eastern Settlement than minor temperature changes.

Arctic Archaeology and Climate Change

An enduring debate in the field of Arctic archaeology has been the extent to which climate change impacted cultural developments in the past. Long-term culture change across the circumpolar Arctic was often highly dynamic, with episodes of rapid migration, regional abandonment, and—in some cases—the disappearance or wholesale replacement of entire cultural traditions. By the 1960s, researchers were exploring the possibility that warming episodes had positive effects on cold-adapted premodern peoples in the Arctic by ( a) reducing the extent of sea ice, ( b) expanding the size and range of marine mammal populations, and ( c) opening new waterways and hunting areas for marine-adapted human groups. Although monocausal climatic arguments for change are now regarded as overly simplistic, the growing threat of contemporary Arctic warming to Indigenous livelihoods has given wider relevance to research into long-term culture–climate interactions. With their capacity to examine deeper cultural responses to climate change, archaeologists are in a unique position to generate human-scale climate adaptation insights that may inform future planning and mitigation efforts. The exceptionally well-preserved cultural and paleo-ecological sequences of the Arctic make it one of the best-suited regions on Earth to address such problems. Ironically, while archaeologists employ an exciting and highly promising new generation of methods and approaches to examine long-term fragility and resilience in Arctic social-ecological systems, many of these frozen paleo-societal archives are fast disappearing due to anthropogenic warming.

North Atlantic variability and its links to European climate over the last 3000 years

The subpolar North Atlantic is a key location for the Earth's climate system. In the Labrador Sea, intense winter air-sea heat exchange drives the formation of deep waters and the surface circulation of warm waters around the subpolar gyre. This process therefore has the ability to modulate the oceanic northward heat transport. Recent studies reveal decadal variability in the formation of Labrador Sea Water. Yet, crucially, its longer-term history and links with European climate remain limited. Here we present new decadally resolved marine proxy reconstructions, which suggest weakened Labrador Sea Water formation and gyre strength with similar timing to the centennial cold periods recorded in terrestrial climate archives and historical records over the last 3000 years. These new data support that subpolar North Atlantic circulation changes, likely forced by increased southward flow of Arctic waters, contributed to modulating the climate of Europe with important societal impacts as revealed in European history.

Climate challenges, vulnerabilities, and food security

This paper identifies rare climate challenges in the long-term history of seven areas, three in the subpolar North Atlantic Islands and four in the arid-to-semiarid deserts of the US Southwest. For each case, the vulnerability to food shortage before the climate challenge is quantified based on eight variables encompassing both environmental and social domains. These data are used to evaluate the relationship between the "weight" of vulnerability before a climate challenge and the nature of social change and food security following a challenge. The outcome of this work is directly applicable to debates about disaster management policy.

Glacier maxima in Baffin Bay during the Medieval Warm Period coeval with Norse settlement

The climatic mechanisms driving the shift from the Medieval Warm Period (MWP) to the Little Ice Age (LIA) in the North Atlantic region are debated. We use cosmogenic beryllium-10 dating to develop a moraine chronology with century-scale resolution over the last millennium and show that alpine glaciers in Baffin Island and western Greenland were at or near their maximum LIA configurations during the proposed general timing of the MWP. Complimentary paleoclimate proxy data suggest that the western North Atlantic region remained cool, whereas the eastern North Atlantic region was comparatively warmer during the MWP-a dipole pattern compatible with a persistent positive phase of the North Atlantic Oscillation. These results demonstrate that over the last millennium, glaciers approached their eventual LIA maxima before what is considered the classic LIA in the Northern Hemisphere. Furthermore, a relatively cool western North Atlantic region during the MWP has implications for understanding Norse migration patterns during the MWP. Our results, paired with other regional climate records, point to nonclimatic factors as contributing to the Norse exodus from the western North Atlantic region.