An ice-core record of Antarctic sea-ice extent in the southern Indian Ocean for the past 300 years

The differing response of ice extent in the Arctic and Antarctic to global average temperature change, over approximately the last three decades, highlights the importance of reconstructing long-term sea-ice history. Here, using high-resolution ice-core records of methanesulfonate (MS–) from the East Antarctic ice sheet in Princess Elizabeth Land, we reconstruct southern Indian Ocean sea-ice extent (SIE) for the sector 62–92° E for the period AD 1708–2000. Annual MS– concentration positively correlates in this sector with satellite-derived SIE for the period 1979–2000 (r² = 0.25, P < 0.02). The 293 year MS– record of proxy SIE shows multi-decadal variations, with large decreases occurring in two warm intervals during the Little Ice Age, and during the 1940s. It is very likely that the global temperature is the controlling factor of Antarctic sea-ice variation at the centennial scale, although there has been a change in phase between them in recent decades.