Sea ice diatoms in ice cores, a novel proxy for reconstructing past Antarctic sea ice changes

Antarctic sea ice plays a key role in modulating regional and global climate. Over the last decade, Antarctic sea ice has presented a rapid decline. However, observational records are short, hindering our ability to directly assess the wider context of the recently observed changes. In the absence of long direct observations, ice core proxy records have the potential to yield valuable information about past environmental changes over long timescales.

In this study, we present multiple records of sea ice diatoms preserved in a set of ice cores retrieved from two sub-Antarctic islands within the seasonal sea ice zone and two coastal Antarctic Peninsula sites. The abundance of sea ice diatoms preserved in ice core layers strongly correlates with spring sea ice concentration upwind from the ice core sites. This strong relationship highlights the sea ice diatom abundance preserved in ice layers as a novel Antarctic sea ice concentration proxy.