Cave atmosphere controls on stalagmite growth rate and palaeoclimate records

Abstract Cave atmosphere P CO 2 partially controls calcite deposition on stalagmites by changing the thermodynamic drive of drip water to deposit calcite. The dissolved carbon dioxide contained in karstic percolation water is generally controlled by the soil P CO 2 , and this CO 2 will degas in any void spaces with a lower P CO 2 , including caves. If void space P CO 2 is higher than the P CO 2 of the water, dissolution may occur. Measured cave air P CO 2 ranges of several caves in different climate regimes suggest that soil temperature is a major control on cave air P CO 2 , but that the observed trend deviates from the modelled trend when soil carbon dioxide production is moisture-limited. Calcite deposition models illustrate how soil and cave air P CO 2 can influence stalagmite growth rates, and demonstrate how gradual temperature changes can skew the geochemical proxy signal in stalagmites in favour of certain seasons and eventually can result in total cessation of growth.