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Abstract Rapid Arctic warming this century will likely cause major water cycle and atmospheric circulation changes, including weakening mid‐latitude westerly winds and more persistent summer high pressures over Fennoscandia. These conditions can cause drought in northern Europe and extreme rainfall in the Mediterranean region. Uncertainties in the spatiotemporal patterns of these predictions can be partially addressed with records of past climate response to rapid change. The early Holocene collapse of the Northern Hemisphere ice sheets provides a natural experiment to evaluate the climate response to rapid changes in boundary conditions. We analyzed lipid biomarker distributions and hydrogen isotope (δ²H) values from Lake Imandra, Kola Peninsula, to infer Holocene summer temperature and summer precipitation δ²H values. Sensitivity tests of a lake model suggest summer precipitation δ²H values are the main mechanism influencing Lake Imandra δ²H values. Summer precipitation isotope values exhibited a nearly 20‰²H‐depletion between 8.6 and 8.0 ka, with²H ‐enriched values before 8.6 ka and²H ‐depleted values 8.0 ka to present. Maximum warmth occurred from 8.5 to 7.0 ka. Climate model experiments suggest that the early Holocene Laurentide Ice Sheet collapse caused a westward shift of the Fennoscandian summer high‐pressure center. This caused a decrease in the proportion of local,²H‐enriched precipitation falling throughout Fennoscandia and an increase in far‐traveled,²H‐depleted precipitation from the mid‐latitudes, circulation that persisted throughout the Holocene. These results illustrate the sensitivity of climate in Fennoscandia and show that circulation regime shifts can occur in response to changes in boundary conditions far upwind. 

The role of high latitude lakes in storing and processing terrestrial organic carbon export is not well understood. We analyzed a 2.7-meter (m) -long sedimentary record from Eight Mile Lake that extends back 15,700 years to evaluate connections between productivity, organic carbon accumulation and late Quaternary environmental change in central Alaska. We analyzed macrofossil radiocarbon, alongside physical and biogeochemical properties. This dataset includes data from 12 sediment cores collected across Eight Mile Lake. These cores span time frames of 1000 - 15,700 years. This dataset includes bulk physical data, organic matter abundance, biogenic silica abundance, particle size, geochronological information, magnetic susceptibility data and hyperspectral imagery. 

The quantity and preservation of carbon-rich organic matter (OM) underlying permafrost uplands, and the evolution of carbon accumulation with millennial climate change, are large sources of uncertainty in carbon cycle feedbacks on climate change. We investigated permafrost OM accumulation and degradation over the Holocene using a transect of sediment cores dating back to at least c. 6-8 ka, from a hillslope in the Eight Mile Lake watershed, central Alaska. This dataset collected from four permafrost sediment cores includes a variety of biogeochemical datasets including radiocarbon, carbon, nitrogen, particle size, amino acids (concentrations and D:L), bulk density and water content. 

Organic-rich surficial materials of the Arctic are a storehouse of frozen carbon (C) of global consequence. Climate ultimately controls the exchange of carbon between this reservoir and the atmosphere, but the long-term relation between climate and permafrost carbon is highly uncertain. This study draws from climate changes that occurred during the recent geologic past (late glacial and Holocene), which serve as natural experiments, to quantify the long-term (millennial-scale) relation between climate and the mass of carbon that accumulated under distinctly different climate states. Whereas previous studies of the effects of climate changes on permafrost carbon have generally focused on lakes and peatlands of low-lying terrain, this study provides complementary information from upland deposits that mantle hilly terrain, possibly the least-well known component of the arctic frozen organic carbon inventory. The project applies and develops new approaches to investigating the relation between climate and carbon sequestration in an understudied setting and at long time scales by bringing together expertise in Arctic paleoecology, paleoclimatology, surficial geology, geochronology and quantitative geomorphology. This paleo perspective provides a unique approach to help infer how permafrost and its C reservoir may react in the future. 

Abstract The quantity and preservation of carbon‐rich organic matter (OM) underlying permafrost uplands, and the evolution of carbon accumulation with millennial climate change, are large sources of uncertainty in carbon cycle feedbacks on climate change. We investigated permafrost OM accumulation and degradation over the Holocene using a transect of sediment cores dating back to at least c. 6 ka, from a hillslope in the Eight Mile Lake watershed, central Alaska. We find decimeter‐scale organic‐rich (111 ± 45 kg C m⁻³) and organic‐poor (49 ± 30 kg C m⁻³) layers below an upper peat, which store 35% ± 11% and 41% ± 20% of the carbon in the upper 1 m, respectively. In organic‐poor layers, scattered¹⁴C ages of plant macrofossils and higher percentages of degradedAlnusandBetulapollen indicate reworking by cryoturbation and hillslope processes. Whereas organic carbon to nitrogen ratios generally indicate OM freshening up‐core, amino acid bacterial biomarkers, includingd‐enantiomers and gamma‐aminobutyric acid, suggest enhanced degradation prior to 5 ka. Carbon accumulation rates increased from ∼4 to 14 g C m⁻² year⁻¹from c. 8 to 0.2 ka, coinciding with decreasing temperatures and increasing moisture regionally, which may have promoted OM accumulation. Carbon stocks within the upper 1 m average 66 ± 13 kg C m⁻², varying from 77 kg C m⁻²in a buried depression on the upper slope to 48 kg C m⁻²downslope. We conclude that heterogeneity in preserved OM reflects a combination of hillslope geomorphic processes, cryoturbation, and climatic variations over the Holocene.