Climate variability of the Common Era (AD 1-2000) in the eastern North American Arctic: Impacts on human migrations

摘要

The eastern North American Arctic has a complex 5000-year prehistory, during which many human population movements occurred over great distances. Archaeologists have interpreted these movements as resulting from many factors, however the effects of climate change are often hypothesized as primary drivers that can "push" human groups to leave some regions, or "pull" them to move to others. Here, we examine climate change at the regional scale over the Common Era using Arctic paleoclimate data derived from a wide suite of biological proxies and geochemical tracers. We consider available statistical composites of high resolution (sub-decadal) paleo-temperature reconstructions for the Arctic region, as well as local-scale reconstructions at century or sub-century scale resolution in three focal regions of archaeological significance relevant to population movements: Victoria Island, Foxe Basin/Baffin Island, and the High Arctic (Ellesmere Island/Northwestern Greenland). We emphasize the two most widespread, though variable, climate change events characteristic of this period: the Medieval Climatic Anomaly and Little Ice Age in the second millennium AD; we also evaluate the evidence for the Roman Warm Period and Dark Ages Cold Period in the first millennium AD, as context for later events. We integrate information on the timing and magnitude of these events across the Canadian Arctic Archipelago, and assess the degree to which they coincide with current understanding of major population movements, with particular emphasis on three migration episodes. First, the expansion of Late Dorset Paleo-Inuit to the Central and High Arctic beginning in the late first millennium AD is plausibly linked to warming temperatures of the MCA. Second, the migration of Thule Inuit from Alaska to the Eastern Arctic beginning ca AD 1250 is not linked to warmer temperatures as previously hypothesized, and is therefore more likely related to social factors in Alaska. Third, the abandonment of northern regions and new settlement of southern regions by Inuit in the mid-second millennium AD is likely linked to a combination of cooling climate and increasing availability of European trade goods. Together, these three case studies indicate that linkages between climate change and migration are complex, variable, and mediated through social and economic factors.