Hydrological modelling of stalagmite δ18O response to glacial-interglacial transitions

Abstract

Stalagmite delta O-18 series currently provide the most robustly dated characterization of glacial terminations. However, uncertainties associated with the stalagmite delta O-18 proxy record arise due to the complexity of flow within karst aquifers. Here we use an integrated climate-soil-groundwater lumped parameter hydrological model to demonstrate the range of potential stalagmite delta O-18 hydrological responses to significant global climate changes. Pseudoproxy stalagmite delta O-18 series were generated for millennial length model simulations, using general circulation model time-slice data for 12, 11, and 10ka for eastern China. Our model demonstrates that the variability within published delta O-18 records from Chinese stalagmites falls within that of modeled pseudoproxy series. We utilize model output to (i) quantify hydrological uncertainty (specifically the relative importance of changing precipitation amount, isotopic composition, and water balance); (ii) identify any nonstationarity in delta O-18 variability and its relationship to climate change; and (iii) demonstrate the processes that produce low-frequency power in stalagmite delta O-18.