1. Holocene hydroclimate variability of the Baltic region inferred from stable isotopes, d-excess and multi-proxy data at lake Nuudsaku, Estonia (NE Europe).
- Author
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Eensalu, Mariliis, Nelson, Daniel B., Buczynska, Anna, Rach, Oliver, Luoto, Tomi P., Poska, Anneli, Klein, Eric S., and Stansell, Nathan D.
- Subjects
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STABLE isotopes , *HOLOCENE Epoch , *CLIMATE sensitivity , *GLOBAL warming , *FOSSIL pollen , *OXYGEN isotopes , *HUMIDITY - Abstract
Long-term hydroclimate records provide an opportunity to understand potential drivers of the past, and give context to modern and future climate warming. A wide variety of proxy data now allow for reconstruction of climate variables that were not previously possible. Here we present a multi-proxy dataset including n -alkane δ2H (δ2H n-alk) values from an open-basin lake in Estonia to reconstruct past hydroclimate conditions for the eastern Baltic region. We complement our sedimentary δ2H n-alk data with existing carbonate-based oxygen stable isotope (δ18O) data to derive deuterium (d -) excess. We present multiple isotopic records and reconstructed relative humidity (ΔRH) values over the Holocene, and link these with modern precipitation δ2H and δ18O values to guide the interpretation of the paleo-proxies. Fossil pollen and chironomid-based temperature reconstructions, as well as biogeochemical data provide additional information for inferring past environmental changes. Our results indicate that the middle Holocene in Estonia had on average 6 ± 3% higher RH values than the late Holocene. The δ18O and δ2H values were also higher during the middle Holocene, which we interpret as increased warm season precipitation. Our reconstructed d -excess values were relatively higher during the middle Holocene, indicating a more northerly or cold source water origin, in comparison to the late Holocene. In addition to the paleoclimatic significance, our results show how multiple quantitative proxies can be combined to characterize hydroclimate sensitivity to changes in relative humidity, temperature and moisture source. • Combined H and O isotope proxies permit d -excess and RH reconstructions. • Sedimentary biomarkers in the eastern Baltic region reflect Holocene hydroclimate. • Higher relative humidity and d-excess values recorded during the middle Holocene. • Relative humidity changes were modeled and quantified using n-alkane proxy. • Northerly moisture sources were dominant in Estonia during the late Holocene. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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