Abstract

Understanding the Holocene/Anthropocene transition along the Greenland coastal margin is important not only for constraining the patterns of environmental variability globally, but also for evaluating the magnitude of recent changes within a longer-term perspective. Diatoms are a widely used tool for reconstructing Holocene environmental changes, as they are ubiquitous, well-preserved, sensitive to a range of environmental variables, and can be used to faithfully reconstruct climatically-relevant lake characteristics over time. Here, two diatom-based records of contrasting anthropogenic change from Greenland are presented: one from the northernmost lake in the world, on the north coast (Kaffeklubben Sø, 83ºN) and one from Lake Igaliku (61ºN), adjacent to a Norse site in southern Greenland. In the North, recent warming has resulted in ice-free conditions (post-1920 AD) that are unprecedented in the context of the last few millennia. In the south, recent agricultural development (post-1975 AD) has fundamentally altered the nutrient dynamics of the lake. These recent changes are unprecedented in the Holocene history of the lake, but also contrast the more muted paleoecological footprint of the Norse landnám (986-1450 AD). Both records show marked anthropogenic changes, but by entirely different pathways (climate vs. land use). The records also demonstrate how diatoms from lake sediments can be used to evaluate the nuances of human perturbations to the high latitude environment within a longer-term perspective.