Stalagmite growth and palaeo-climate: the numerical perspective

The growth of stalagmites can be approximated by a simple mathematical model, which depends on growth rate and equilibrium radius. These two parameters are controlled by the climate. Temperature variations derived from ice and deep-sea core data, together with models for changes in precipitation and soil cover, are used to derive stalagmite stratigraphies, which reflect the palaeo-climate variations imposed. In general, stalagmite growth is strongly correlated to temperature and the amount of carbon dioxide available in the soil. Furthermore, precipitation is correlated to the stalagmite diameter. However, several assumptions need to be made: (i) A functional relationship between temperature on the one hand and precipitation and soil cover on the other needs to be established. (ii) The kinetics of calcite dissolution and precipitation needs to be assigned, either under soil and epikarst conditions open to the atmosphere or under fractured rock conditions closed from the atmosphere. These assumptions are difficult to access from field data, and therefore a stalagmite stratigraphy can be ambiguous and not easily converted back into an unknown palaeo-climate signal.