The Law Dome MSA sea ice proxy record: analysis of modern satellite data and re-examination of archival satellite imagery

Understanding the long term trends in sea ice coverage is important, particularly in the context of recent reports of increases in Antarctic sea ice extent. Prior to the satellite era, ice core records have been used as a proxy for past sea ice extent in Antarctica, allowing investigations of the natural variability of Antarctic sea ice extent. The Law Dome MSA sea ice proxy has been recognised as an important tool for reconstructing sea ice, however not without it’s limitations. Here, we present an updated record for the Methanesulphonic acid (MSA) data from the Law Dome site (to 2013) and investigate the recent changes in Antarctic sea ice extent. We also extend the proxy calibration period further back in time by including reanalysis of old Nimbus I satellite information from the mid 1960s to the mid 1970s. Our data suggests that recent reports of increases in Antarctic sea ice extent remain within natural variability, a result consistent with attribution and detection studies for this region.