Summary: | Understanding the long term trends in sea ice coverage is important, particularly in thecontext of recent reports of increases in Antarctic sea ice extent. Prior to the satellite era, icecore records have been used as a proxy for past sea ice extent in Antarctica, allowinginvestigations of the natural variability of Antarctic sea ice extent. The Law Dome MSA seaice proxy has been recognised as an important tool for reconstructing sea ice, however notwithout its 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 Antarcticsea ice extent. We also extend the proxy calibration period further back in time by includingreanalysis of old Nimbus I satellite information from the mid 1960s to the mid 1970s. Ourdata suggests that recent reports of increases in Antarctic sea ice extent remain withinnatural variability, a result consistent with attribution and detection studies for this region.
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