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Title: Seasonal precipitation variability on Svalbard inferred from Holocene sedimentary leaf wax δ 2 H

Svalbard spans large climate gradients, associated with atmospheric circulation patterns and variations in ocean heat content and sea ice cover. Future precipitation increases are projected to peak in the northeast and to mainly occur in winter, but uncertainties underscore the need for reconstructions of long‐term spatial and temporal variations in precipitation amounts and seasonality. We use lipid biomarkers from four sedimentary lake records along a climatic gradient from western to northeastern Svalbard to reconstruct Holocene water cycle changes. We measured the leaf wax hydrogen isotopic composition of long‐chain (terrestrial) and mid‐chain (aquatic)n‐alkanoic acids, reflecting δ2H of precipitation (δ2Hprecip) and lake water (δ2Hlake), respectively. δ2Hprecipvalues mainly reflect summer precipitation δ2H and evapotranspiration, whereas δ2Hlakevalues can reflect various precipitation seasonality due to varying lake hydrology. For one lake, we used the difference between δ2Hprecipand δ2Hlakeprecip‐lake) to infer summer evapotranspiration changes. Relatively2H‐enriched δ2Hprecipvalues and higher εprecip‐lakein the Early and Middle Holocene suggest warm summers with higher evapotranspiration, and/or more proximal summer moisture. Afterc. 6 cal. ka BP,2H‐depleted δ2Hprecipvalues and lower εprecip‐lakeindicate summer cooling, less evapotranspiration, or more distally derived moisture. Early to Middle Holocene decrease in δ2Hlakevalues in two northern Spitsbergen lakes reflects an increase in the proportion of winter relative to summer precipitation, associated with regional warming and increased moisture supply, which may be due to increased distal moisture supply and/or reduced sea ice cover. Our northern Svalbard δ2Hlakerecords suggest great Late Holocene climate variability with periodic winter precipitation increases or decreases in summer precipitation inflow to the lakes. We find that Holocene summer precipitation δ2H values mainly follow changes in summer insolation and temperature, whereas the seasonal distribution of precipitation is sensitive to catchment hydrology, regional ocean surface conditions, and moisture source changes.

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Medium: X Size: p. 430-452
p. 430-452
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National Science Foundation
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