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Millennial-length forward models and pseudoproxies of stalagmited18O: an example from NW Scotland
journal contributionposted on 2023-05-18, 14:36 authored by Baker, A, Bradley, C, Phipps, SJ, Fischer, M, Fairchild, IJ, Fuller, L, Spotl, C, Azcurra, C
The stable oxygen isotope parameter 18O remains the most widely utilised speleothem proxy for past climate reconstructions. Uncertainty can be introduced into stalagmite 18O from a number of factors, one of which is the heterogeneity of groundwater flow in karstified aquifers. Here, we present a lumped parameter hydrological model, KarstFor, which is capable of generating monthly simulations of surface water - ground water - stalagmite 18O for more than thousand-year time periods. Using a variety of climate input series, we use this model for the first time to compare observational with modelled (pseudoproxy) stalagmite 18O series for a site at Assynt, NW Scotland, where our knowledge of 18O systematics is relatively well understood. The use of forward modelling allows us to quantify the relative contributions of climate, peat and karst hydrology, and disequilibrium effects in stalagmite 18O, from which we can identify potential stalagmite 18O responses to climate variability. Comparison of the modelled and actual stalagmite 18O for two stalagmites from the site demonstrates that, for the period of overlapping growth, the two series do not correlate with one another, but forward modelling demonstrates that this falls within the range explicable by differences in flow routing to the stalagmites. Pseudoproxy 18O stalagmite series highlight the potential significance of peat hydrology in controlling stalagmite 18O over the last 1000 yr at this site.
Publication titleClimate of the Past
Department/SchoolInstitute for Marine and Antarctic Studies
Place of publicationGermany
Rights statementCopyright 2012 The Authors Licensed under Creative Commons Attribution 3.0 Unported http://creativecommons.org/licenses/by/3.0/legalcode