Predicting the loss of organic archaeological deposits at a regional scale in Greenland.

Across the Arctic, microbial degradation is actively destroying irreplaceable cultural and environmental records that have been preserved within archaeological deposits for millennia. Because it is not possible to survey the many sites in this remote part of the world, new methods are urgently needed to detect and assess the potential degradation. Here, we investigate organic deposits at seven archaeological sites located along the dominating west-east climatic gradient in West Greenland. We show that, regardless of age, depositional history and environmental conditions, all organic deposits are highly vulnerable to degradation. A state-of-the-art model that simulates the effect of future climate change on degradation indicates that 30-70% of the archaeological fraction of organic carbon (OC) could disappear within the next 80 years. This range reflects the variation within the climatic gradient and the future climate scenario applied (RCP 4.5 and RCP 8.5). All archaeological deposits are expected to experience a substantial loss, but the most rapid degradation seems to occur in the continental inland areas of the region, dominated by dry and warm summers. This suggests that organic remains from the Norse Viking Age settlers are especially under threat in the coming years.

Footprints from the past: The influence of past human activities on vegetation and soil across five archaeological sites in Greenland.

Climate change has irrevocable consequences for the otherwise well-preserved archaeological deposits in the Arctic. Vegetation changes are expected to impact archaeological sites, but currently the effects are poorly understood. In this article we investigate five archaeological sites and the surrounding natural areas along a climate gradient in Southwest Greenland in terms of vegetation types, above- and below-ground biomass, soil geochemistry and spectral properties. The investigations are based on data from site-sampling and optical remote sensing from an unmanned aerial vehicle (UAV) and satellites. Results show that the archaeological sites are dominated by graminoids with approximately two times more above- and below-ground biomass than the surrounding areas, where the vegetation is more heterogeneous. This difference is associated with a 2-6 times higher content of plant available phosphorus and water extractable nitrate and ammonium in the archaeological deposits compared to the surrounding soil. Furthermore, the vegetation at archaeological sites is less affected by the regional climate variations than the surrounding natural areas. This suggests that soil-vegetation interactions at archaeological sites are markedly different from the natural environment. Thus, the long-term vulnerability of buried archaeological remains cannot be assessed based on existing projections of Arctic vegetation change. Finally, the study demonstrates that vegetation within archaeological sites has distinct spectral properties, and there is a great potential for using satellite imagery for large scale vegetation monitoring of archaeological sites and for archaeological prospection in the Arctic.