AMHERST, Mass. – Faculty and graduate students from the Climate System Research Center at the University of Massachusetts Amherst have returned to campus with sediment core samples lifted from the lakes of southern Greenland. Funded by the National Science Foundation, their investigation of the sediment cores will provide new data on temperature change over the last 1,500 years in a region linked to the broader climate dynamics of the North Atlantic. Their findings may also shed light on the folklore associated with Viking farmsteads that were abandoned in the 15th century.
Center director Raymond Bradley, Ph.D. student Greg DeWet and master’s student Daniel Miller spent several weeks in Greenland during summer collecting the sediment cores. Naja Motzfeldt, an Eskimology scholar from the area, acted as an impromptu translator for 71-year-old Christian Egede, a farmer and traditional accordion player who traces his ancestors through seven generations back to Norway. His grandfather re-established a sheep farm in southern Greenland in 1914.
Referring to the remains of multiple Norse farms visible on the coastal hillsides, Egede told the team, “Nobody knows why the Norsemen disappeared. It might be climate change, or there might have been a war between the Norsemen and the Inuit people, and the Inuit won this war. But nobody really knows why.”
As Bradley explains, “Archaeological and historical sources paint a picture of relatively successful communities relying on farming and marine resources that provided an adequate economic foundation for many generations of settlers. Churches were built, and in total around 20,000 people over the course of several hundred years settled in this area - maybe 3 or 4,000 at its maximum. People will say, ‘Oh, it got cold and they died,’ but in fact the evidence for that is pretty limited. There aren’t any long-term paleoclimate records from this area. We hope to find out more.”
Bradley says in the lab they will “look at the sediments for a specific proxy that people haven’t used before in this area, which is to look at organic biomarkers, or molecular compounds, that are produced by bacteria that live in the lake and in the soils around the lake, and also by algae that live in the water column. These organisms change their chemical composition, the membrane structure, as a response to temperature. We’ll look at these compounds and try to reconstruct how the temperature changed over time.”
As the geoscientists point out, the climate in southern Greenland is a key area for reconstructing the North Atlantic Oscillation, a major pattern of northern hemisphere climate, and is also linked to Atlantic Meridional Overturning Circulation changes, an important ocean process controlling North Atlantic climate. They add that studies suggest this seawater circulation factor has been weaker in recent decades than at any time in the last 1,000 years, in the same region where the Norse settlements were abandoned.
A new website is being planned by the researchers to explain changes in North Atlantic climate and the history of human migration across the region. It will connect the general public with different aspects of the scientific research. The project supports a geosciences doctoral student and undergraduates from the Commonwealth Honors College who are learning modern biogeochemistry techniques and applying them to a fascinating archaeological problem, Bradley says.