Continuous records of human-environment interaction in the Lofoten Islands of Arctic Norway based on fecal lipids and alkenone paleothermometry

Throughout the Holocene, prehistoric human populations adapted to environmental changes, including those caused by temperature and sea level variations. Proxy-based records of landscape use and climate variability help us understand how ancient societies responded during times of change. Specifically, concentrations of fecal lipids in lake sediment cores can provide documentation of human and livestock presence and population changes within a watershed. Combining continuous fecal lipid-based records of human activity from lake sediment cores with climate reconstructions from the same cores allows us to evaluate past human-climate-landscape interactions at local to regional spatial scales. The Lofoten Islands of Arctic Norway (68°N) have been inhabited since at least 5500 cal yr BP, with intensive agricultural activities beginning around 2500 cal yr BP. The archipelago is located off the coast of Arctic Norway, making it sensitive to changes in regional ocean circulation patterns; furthermore, isostatic adjustment has led to local sea level lowering of 2-3m during the late Holocene. The climate sensitivity and long history of human occupation in the Lofoten Islands makes for an interesting case study of past human-environment interactions. D'Anjou et al., 2012, reported that fecal lipid concentrations in one lake near the former chieftain center of Borg on the island of Vestvågøy fluctuated with tree-ring based climate records from Northern Scandinavia. Here, we build on this work by analyzing fecal lipids in sediment cores from a suite of five lakes within the main agricultural valley of Vestvågøy. Chronologies for each sediment core have been determined through radiocarbon dating of plant macrofossils, with the longest record reaching the Younger Dryas. We find that, following human settlement, total fecal lipid concentrations in sediment from multiple lakes increased by more than an order of magnitude. Ongoing work will increase the resolution of the fecal lipid records to sub-centennial scale. Furthermore, we will present a new local summer temperature record spanning the agricultural period using lacustrine alkenone unsaturation ratios. Together, these new records will shed light on past changes in climate in Arctic Norway, and how climate and sea level variations impacted local human history.