New research led by PhD student Ruthie Halberstadt definitively resolves a long-standing discrepancy in the geologic record that pitted studies of marine ice-sheet behavior against those that reconstructed past conditions on land. The research, published recently in the journal Geology, and funded by the National Science Foundation and the National Environment Research Council, lends additional weight to evidence that the Antarctic Ice Sheet is sensitive to small changes in CO2 levels and that, in the past, large portions of the ice sheet could have disappeared under CO2 levels similar to today.