Reconstruction of climate at the Norse Settlements of Greenland over the last two millennia using organic biomarkers in lake sediments

The climate in southern Greenland is a key area for reconstructions of the North Atlantic Oscillation, a major pattern of northern hemisphere climate, and is also linked to Atlantic Meridional Overturning Circulation changes, an important oceanic process controlling north Atlantic climate, which recent studies suggest has been weaker over recent decades than at any time in the last 1000 years. This is also the region where Norse settlements were abandoned by the early-15th century; many questions still remain about the causative factors. Although climate change is often cited as the reason for settlement failure, this explanation rests on a very poorly constrained scientific foundation and other explanations have also been proposed. Inferences about climatic conditions in the region often have been derived from far distant sources, generally at high elevations on the Greenland Ice Sheet, where climatic conditions are completely different. This project will produce records with multidecadal (15-25 year) resolution from the study region, spanning the last 1500-2000 years. This will be accomplished using new organic geochemical techniques and will contribute to the calibration and understanding of these methodologies. This project will partially support a productive young scientist (Prof. Isla Castaneda) during the formative years of her career. It will also provide support for the training of a graduate student. The principal investigators (PIs) will contribute to a University of Massachusetts summer program designed to engage 12 to 18 year old girls, most from under-represented or low income groups, in STEM fields. The PIs and the supported graduate student will participate in university-sponsored middle and high school teacher training programs. Finally, undergraduate honors students often participate in the activities of co-PI's lab. She expects that a number of honors theses and senior projects will result from the research associated with this project. All of this contributes to development of the nation's STEM workforce. The project will continue an established international collaboration with French scientists. The disappearance of the Norse communities in Greenland and its potential linkage to climate change have significant human interest upon which the PIs propose to capitalize. Their outreach activities include composing articles for popular science magazines and development of a project web site. It is also anticipated that the PI will continue his productive interactions with the local media, both print and electronic. This project will generate new high resolution, quantitative records of temperature and hydrology for the past 2,000 years from lakes in coastal regions of southern and southwestern Greenland, an area that has important links to the broader climate dynamics of the North Atlantic. It also will shed light on climatic fluctuations during the period of Norse settlement in the region. Novel organic geochemical techniques will be used for past temperature reconstruction (branched glycerol dialkyl glycerol tetraethers) and for estimates of changes in evaporation (leaf wax deuterium isotopes) over time.