A global Bayesian temperature calibration for lacustrine brGDGTs

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Authors

Pablo Martinez Sosa, Jess Tierney, Ioana Cristina Stefanescu, Emily Dearing Crampton-Flood, Bryan N Shuman, Cody Routson

Abstract

Despite widespread use of branched glycerol dialkyl glycerol tetraethers (brGDGTs) for paleo-temperature reconstruction, no global calibration for their application in lakes has been generated since improved analytical methods have allowed for the separation of the structural isomers. This is a substantial obstacle for the application of this tool as soil calibrations underestimate temperature values when applied to lake sediments. Here, we present a comprehensive dataset (N = 261) of lacustrine brGDGT distributions spanning a wide range of geographical locations, environmental temperatures, and lakewater pH values. Empirical Orthogonal Function (EOF) analysis on the fractional abundance of brGDGTS indicates that temperature exerts a strong control (explaining 86% of the variance) on the lipid distribution. However, the influence of water chemistry is less clear, as pH and conductivity have a weak influence on brGDGT distributions. We use our dataset to generate a new Bayesian temperature calibration, which has an R²= 0.85 and RMSE = 2.8°C. Application of this new calibration to a previously published lake core record demonstrates that it generates values comparable with instrumental observations. Our new calibration facilitates the use of lacustrine brGDGTs to reconstruct continental temperatures, a vital piece of information for understanding past climates.

DOI

https://doi.org/10.31223/X5PS3P

Subjects

Biogeochemistry, Climate

Keywords

Bayesian statistics, lakes, brGDGTs, calibration

Dates

Published: 2020-11-13 18:42

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License

CC BY Attribution 4.0 International

Additional Metadata

Conflict of interest statement:
None

Data Availability (Reason not available):
Data is currently being submitted to Pangea, but link is not yet available

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