An assessment of Antarctic ice sheet dynamics from a Pliocene polar paleoclimate archive

The potential impact of East Antarctic Ice Sheet (EAIS) response to warming over the next century is of major concern, particularly due to its influence on sea level rise. Efforts to understand its impact are limited due to the restrictions of short-term modeling, as well as the assumption that all ice behaves similarly across the EAIS, meriting the need for further study over longer time periods. The early Pliocene (5.33-2.58 Ma) is the most suitable period of time in which to assess EAIS dynamics because of its similarity to modern tectonic configuration and similar CO2 estimates (~400 ppm). Due to a paucity of records, the present study expands on the existing knowledge of ice sheet dynamics by providing a reconstruction of ice-rafting history in a previously unstudied sector of the EAIS. The aim of this study is to evaluate the behavior of the Wilkes Land ice sheet and whether its response is part of a continental response or on a smaller, local scale. A high-resolution record of ice-rafting history in the Wilkes Land region from IODP Site U1359 was used to (1) identify periods of advance and retreat during the early Pliocene, (2) determine the orbital variations within the ice-rafting record, (3) assess the effects of warming on the interaction between the ice sheet and Southern Ocean during the Pliocene Climatic Optimum and (4) evaluate the behavior of the EAIS during early Pliocene warmth through regional correlation. A time series analysis to assess the orbital variations of the ice sheet determined a transition from obliquity forced to precession forced variability of ice-rafting ~4.6 Ma. Concurrently, geochemical analysis revealed enhanced downwelling may have lead to greater venting of CO2 during deglaciation, accompanied by higher productivity in response to increased iron-bearing dust fertilization. A regional correlation shows that the ice sheet was susceptible to warming during the Pliocene Climatic Optimum, as opposed to the later mid-Pliocene Warm Period, where the ice sheet remained in a retreated position.