Subglacial Precipitates Record Antarctic Ice Sheet Response to Southern Ocean Warming

Subglacial calcite precipitation is thought to occur in East Antarctica during periods when warm Southern Ocean waters access the ice sheet margin. Here we present an expanded precipitate archive that includes a continent-wide compilation of 38 new and previously reported calcite ²³⁴U-²³⁰Th ages with isotopic compositional data. These data are interpreted to record periods when interior meltwaters are exported to the ice sheet margins as a result of ice acceleration and thinning. An assessment of coincidence between ²³⁴U-²³⁰Th dates, ranging from 16 to 256 ka, and peaks in Southern Ocean temperature yields a statistically significant correlation. Additional comparison of precipitate dates and climate data finds that calcite formation and ice acceleration cluster within periods of enhanced millennial scale climate variability as well as high global ice volume. This sensitivity to background climate is consistent with the hypothesis that these factors exert some control on ice sheet response to changes in climate.