Seasonal precipitation variability on Svalbard inferred from Holocene sedimentary leaf wax δ2H

• Published in: Boreas
• Main Authors: Kjellman, Sofia Elisabeth, Thomas, Elizabeth K., Farnsworth, Wesley R., Cowling, Owen C., Allaart, Lis, Brynjólfsson, Skafti, Schomacker, Anders
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2024
• Subjects: Svalbard; Sea ice; Spitsbergen
• Online Access: https://hdl.handle.net/10037/33714; https://doi.org/10.1111/bor.12661

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 δ 2 H of precipitation (δ 2 H precip ) and lake water (δ 2 H lake ), respectively. δ 2 H precip values mainly reflect summer precipitation δ 2 H and evapotranspiration, whereas δ 2 H lake values can reflect various precipitation seasonality due to varying lake hydrology. For one lake, we used the difference between δ 2 H precip and δ 2 H lake (ε precip-lake ) to infer summer evapotranspiration changes. Relatively 2H-enriched δ 2 H precip values and higher εprecip-lake in the Early and Middle Holocene suggest warm summers with higher evapotranspiration, and/or more proximal summer moisture. After c. 6 cal. ka BP, 2 H-depleted δ 2 H precip values and lower εprecip-lake indicate summer cooling, less evapotranspiration, or more distally derived moisture. Early to Middle Holocene decrease in δ 2 H lake values 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 δ 2 H lake records 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 δ 2 H values mainly follow changes in ...