1150 year long ice core record of the Ross Sea Polynya, Antarctica

TL;DR

This study analyzes a 1150-year ice core record from Antarctica's Ross Sea Polynya to understand its historical behavior and predict future changes related to climate variability and anthropogenic effects.

Contribution

It introduces the first deep ice core-based proxy for Ross Sea Polynya activity, linking atmospheric Ba fluctuations to polynya dynamics over 1150 years.

Findings

RSP area was smallest during recent times.

RSP fluctuations correlate with Amundsen Sea Low strength.

Historical RSP variability linked to climate oscillations.

Abstract

Knowledge of the past behavior of Antarctic polynyas such as the Ross and Weddell Seas contributes to the understanding of biological productivity, sea ice production, katabatic and Southern Hemisphere Westerly (SHW) wind strength, Antarctic bottom water (ABW) formation, and marine CO2 sequestration. Previous studies link barium (Ba) marine sedimentation to polynya primary productivity (Bonn et al., 1998; McManus et al., 2002; Pirrung et al., 2008), polynya area to katabatic wind strength and proximal cyclones (Bromwich et al., 1998; Drucker et al., 2011), and highlight the influence of Ross Ice Shelf calving event effects on the Ross Sea Polynya (RSP) (Rhodes et al., 2009). Here we use the RICE ice core, located just 120 km from the Ross Ice Shelf front to capture 1150 years of RSP behavior. We link atmospheric Ba fluctuations to Ba marine sedimentation in the summer Ross Sea Polynya, creating the first deep ice core based RSP proxy. RSP area is currently the smallest ever observed over our 1150-year record, and varied throughout the Little Ice Age with fluctuations in Amundsen Sea Low (ASL) strength related with Ross Sea cyclones. Past RSP reconstructions allow us to predict future responses of RSP area to future climate change, which is of special interest considering the recent disappearance of the Weddell Sea Polynya in response to anthropogenic forcing (de Lavergne et al., 2014).