A record of Antarctic sea ice extent in the Southern Indian Ocean for the past 300 yr and its relationship with global mean temperature

Abstract. 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 70° E–100° E for the period 1708–2000 A.D. Annual MS⁻ concentration positively correlates in this sector with satellite-derived SIE for the period 1973–2000 (P < 0.05). The 293 yr 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. However, after the 1980s there is a change in phase between Antarctic SIE and global temperature change, with both increasing. This paradox is probably attributable to the strong anomaly in the Southern Annular Mode (SAM) in the recent three decades.