SISALv2: a comprehensive speleothem isotope database with multiple age–depth models

Characterizing the temporal uncertainty in palaeoclimate records is crucial for analysing past climate change, correlating climate events between records, assessing climate periodicities, identifying potential triggers and evaluating climate model simulations. The first global compilation of speleothem isotope records by the SISAL (Speleothem Isotope Synthesis and Analysis) working group showed that age model uncertainties are not systematically reported in the published literature, and these are only available for a limited number of records (ca. 15 %, n = 107/691). To improve the usefulness of the SISAL database, we have (i) improved the database’s spatio-temporal coverage and (ii) created new chronologies using seven different approaches for age– depth modelling. We have applied these alternative chronologies to the records from the first version of the SISAL database (SISALv1) and to new records compiled since the release of SISALv1. This paper documents the necessary changes in the structure of the SISAL database to accommodate the inclusion of the new age models and their uncertainties as well as the expansion of the database to include new records and the qualitycontrol measures applied. This paper also documents the age–depth model approaches used to calculate the new chronologies. The updated version of the SISAL database (SISALv2) contains isotopic data from 691 speleothem records from 294 cave sites and new age–depth models, including age–depth temporal uncertainties for 512 speleothems. SISALv2 is available at https://doi.org/10.17864/1947.256 (Comas-Bru et al., 2020a).
The design and creation of v2 of the database were supported by funding to Sandy P. Harrison from the ERCfunded project GC2.0 (Global Change 2.0: Unlocking the past for a clearer future; grant no. 694481) and the Geological Survey Ireland Short Call 2017 (Developing a toolkit for model evaluation using speleothem isotope data; grant no. 2017-SC-056) award to Laia Comas-Bru. Sandy P. Harrison and Laia Comas-Bru received additional support from the ERC-funded project GC2.0 and from the JPI-Belmont project “PAlaeo-Constraints on Monsoon Evolution and Dynamics (PACMEDY)” through the UK Natural Environmental Research Council (NERC). Laia Comas-Bru and Belen Martrat received support from the CSIC scientific international collaboration programme I-LINKA20102 IBCC-lo2k. Kira Rehfeld and Denis Scholz acknowledge support by the Deutsche Forschungsgemeinschaft (DFG; codes RE3994/2-1 and SCHO 1274/11-1).