Caves and palaeohydrology

Speleothems are useful for obtaining precisely dated records of past climate and environmental change on a variety of timescales.

These records of past climate or environmental change are obtained by measuring chemical indicators - or inorganic proxies - preserved within stalagmite calcium carbonate (CaCO₃), such as stable isotopes of oxygen and carbon, and to a lesser extent, trace elements and biomarkers.

Combining an understanding of how climatic and environmental signals are transferred from the surface into speleothems with ways of calibrating these chemical proxies allows researchers to obtain unique records of past climate and environment.

Current Research at UNSW

CWI members Andy Baker, Martin Andersen,  Bryce Kelly, Helen Rutlidge, Katie Coleborn, Gabriel Rau and many collaborators are actively pursuing the latest technologies and techniques for obtaining records of past climatic, environmental and hydrogeological changes from speleothems. These include:

  • Development and application of isotope-enabled lumped parameter models to understand the hydrological uncertainty introduced by the complexities of groundwater flow into stalagmite oxygen isotope records. Collaboration with Dr Chris Bradley, Prof Ian Fairchild and Dr. Mark Cuthbert (University of Birmingham) and Pauline Treble (ANSTO), with publications in the journals Climate of the Past, Quaternary Science Reviews, Geophysical Research Letters, Earth and Planetary Science Letters and Global and Planetary Change. The Karstolution model code can be found here.
  • Understanding the impact of fire on karst processes, in collaboration with Pauline Treble (ANSTO), Prof Ian Fairchild (Birmingham), and colleagues from NSW OEH and Optimal Karst Management with publications in Environmental Earth Sciences, Hydrology and Earth System Sciences, Scientific Reports, Geochimica et Cosmochimica Acta and Global and Planetary Change.
  • The use of novel geostatistical techniques, to better understand drip water hydrology and the climate signal contained within stalagmites, with recent publications in the journal Geophysical Research Letters and applications to a North Atlantic climate reconstruction published in  Scientific Reports.
  • The investigation of decadal time period rainfall variability in Ethiopia using annually laminated stalagmites and high resolution oxygen isotope analyses. Collaboration with the University of Birmingham and UK isotope geosciences facilities, with publication in the journal The Holocene.
  • The establishment of a stable isotope facility at UNSW Analytical Centre for the analysis of the oxygen and carbon isotopes of speleothems.
  • The improved understanding of water movement through the unsaturated zone of fractured limestones through the innovative monitoring of the hydrological variability of stalagmite forming drip waters and use of novel tracers at the Wellington Caves, NSW. Recent publications include the identification of trace element signatures is semi-arid karst drip waters (Geochimica et Cosmochimic Acta), evaporative cooling of dripwaters and the quantification of subsurface evaporative fractionation of oxygen isotopes (Earth and Planetary Science Letters). A recent review paper considers the how modelling the karst vadose zone can be used to better understand speleothem paleoclimate records (Earth-Science Reviews).
  • The development of lignin phenol and GDGT biomolecular proxies in stalagmites, with Alison Blyth (Curtin) and Stuart Khan (UNSW), with publications in Organic Geochemistry and Quaternary Science Reviews.
  • The completion of the research text 'Speleothem Science' by Ian Fairchild (Birmingham) and Andy Baker, published by Wiley-Blackwell in 2012.
  • Co-convening the 6th International Conference on 'Climate Change: the Karst Record' held in the UK in 2011, the 8th International Conference at Austin, Texas in 2017 and running a karst hydrology workshop in the 7th International Conference at Melbourne in 2014.
  • The development of replicated glacial-interglacial timescale records of variations in groundwater recharge in SE Australia using stalagmite proxies, in collaboration with colleagues at ANSTO.

Further information: Professor Andy Baker