Rapid Coupling Between Southern Hemisphere Climate Changes and East
Antarctic Subglacial Water Dynamics during MIS 5e
Abstract
The continent-wide hydrologic system below the Antarctic Ice Sheet helps
regulate ice sheet dynamics and controls the biogeochemical fluxes from
the continent to the Southern Ocean. Yet, the paucity of well dated,
long-term records describing the evolution of Antarctic subglacial
meltwater flow on centennial to millennial scales limits our ability to
test potential feedbacks between ice motion, climate, and basal
hydrology. Here we present a ten-thousand-year record of basal water
dynamics and chemistry from ~110 ka sediment-bearing
calcite precipitates that formed beneath the East Antarctic Ice Sheet
during MIS 5e. Time series of sediment frequency and grain size indicate
that subglacial meltwater flushing becomes more vigorous within decades
of millennial-scale Southern Hemisphere warming events. Similarly,
shifts in calcite geochemical composition record climate-driven changes
in subglacial water provenance during these warm periods. The
synchronized and sustained (>1 ka) changes in Antarctic basal
hydrology with climate indicate rapid impact of climate forcing on
subglacial water drainage systems. This connection between climate
change and Antarctic basal hydrologic flow represents a potentially
important feedback that can affect ice volume and nutrient discharge to
the Southern Ocean on geologic timescales.