PAGES - Past Global Changes

SISAL - Speleothem Isotopes Synthesis and AnaLysis

Summary

The Speleothem Isotopes Synthesis & Analysis (SISAL) working group will bring together speleothem scientists, speleothem-process modelers, statisticians and climate modelers to develop a global synthesis of speleothem isotopes that can be used both to explore past climate changes and in model evaluation.
Sign up to the SISAL mailing list.
Twitter: @SISAL_wg

Goals

- Identify the current status of speleothem-based paleoclimate reconstructions globally.
- Initiate the compilation of raw data and metadata needed to create a publicly available global database of speleothem δ¹⁸O and δ¹³C records.
- Agree on structure and contents of the global database.
- Discuss how the speleothem data can be used in paleoclimate modeling studies.
- Identify the needs and potential downfalls of these climate archives before the paleoclimate community can use the dataset to feed model simulations in the framework of the next phase of the Coupled Model Intercomparison Project (CMIP6).

Leaders

Laia Comas-Bru (University College Dublin, Ireland) (Lead and mailing list administrator)
Michael Deininger (University of Mainz, Germany)
Sandy Harrison (University of Reading, UK)
Miriam Bar-Matthews (Geological Survey of Israel)
Andy Baker (UNSW Sydney, Australia)
Wuhui Duan (Institute of Geology and Geophysics, Chinese Academy of Sciences, China)
Nicolás Strikis (Universidade Federal Fluminense, Rio de Janeiro, Brazil)

Timeline

Launch			Synthesis

Feb 2017	2018	2019	Feb 2020

Speleothems are secondary cave deposits formed mostly from calcium carbonates (CaCO₃). These climate archives are well distributed worldwide and thus they are not only valuable archives for regional climate but also for continental and inter-continental comparisons. Also, due to the high precision of Uranium-series dating, speleothems provide an opportunity to trace leads and lags of global events. The different types of measurements made on speleothems, including the stable isotopes of oxygen and carbon (δ¹⁸O, δ¹³C) and various trace elements, can be used to reconstruct past changes in the hydrological cycle as well as changes in atmospheric composition.

Speleothems provide a unique opportunity for reconstructing climate drivers and change on various spatial and temporal scales during the last 21,000 years and beyond. These reconstructions can be used to evaluate state-of-the-art climate models that explicitly simulate water and carbon isotopes and/or atmospheric tracers such as dust. There are more than 400 published speleothem records; synthesis of these records, including assessment of the quality and reliability of individual records, is the goal of the SISAL (Speleothem Isotopes Synthesis and AnaLysis) WG.

The map illustrates a state of the art overview of locations of investigated speleothems that were used for palaeoclimate studies (red closed circles); the white closed circles indicate the speleothems, whose datasets are available on the NOAA palaeoclimatology database – these are only 19% of the speleothems pictured here (Feb. 2014). The two pie charts illustrate the spatial and temporal distribution of the speleothems. (Bottom pie chart) 55% of the speleothems grew within the Holocene and 45% are Pleistocene, distributed over two million years; however, most of them grew between MIS 7 and MIS 2. (Top pie chart) 39% of the speleothems grew in Europe; 17% in Asia; 13% in North America; 12% in Oceania; 6% in the Middle East; 5% in South America and 3% Middle America and Africa, respectively (figure adopted and modified from Deininger, 2013).