Mid-Holocene reinforcement of North Atlantic atmospheric circulation variability from a western Baltic lake sediment record

Abstract. Knowledge about the timing, amplitude and spatial gradients of Holocene environmental variability in circum-Baltic region is key to understanding its responses ongoing climate change. Based on a multi-dating proxy approach, we reconstruct changes productivity using total organic carbon (TOC) contents sediments Lake Kälksjön (KKJ) from west–central Sweden spanning last 9612 (+255/-114) years. An exception period 1878 CE until today, which sedimentation was dominated by anthropogenic lake level lowering land use. In-lake higher during periods warmer winters with shortened ice cover prolonged growing seasons. A multi-millennial increase throughout ∼ 9600 years associated progressively northwestern Europe, likely triggered coinciding Northern Hemisphere winter insolation. Decadal centennial KKJ tend correspond more positive North Atlantic Oscillation (NAO) polarity, as reconstructed for 8000 In consequence, assume our decadal record complete provide qualitative NAO polarity. shift towards at 5450 cal BP hypothesized reflect reinforcement NAO-like atmospheric circulation variability, possibly driven vigorous deep-water formation.