The geochemistry of cave calcite deposits as a record of past climate

Cave calcite deposits, and stalagmites specifically, are proving to be critical recorders of paleoclimate. Stalagmites develop from the slow accumulation of calcite deposited after the degassing of carbon dioxide from percolation water in caves. Stalagmites are therefore theoretically capable of recording the hydrochemistry of every drip of water that impacts their surface, but complications involving hydrology, cave air PCO2 variability, intra-aquifer processing, and petrography preclude straightforward interpretation. Nevertheless, stalagmite climate proxy records using stable isotopes, particularly of oxygen, are reconstructing the timing, structure, and in some cases magnitude of climate shifts worldwide. Trace element to calcium ratios in stalagmite are a promising new proxy for both independent reconstruction of climate and for supporting oxygen isotope ratios. Extensive monitoring of individual cave sites is required to most accurately interpret stalagmite proxy records.