The Southern Ocean marine ice record of the early historical, circum-Antarctic voyages of Cook and Bellingshausen

Abstract. The circum-navigations of Cook’s Second Voyage (1772–1775) and Bellingshausen (1819–1821) were attempts to find any great southern land mass poleward of ~50° S and consequently involved sailing for three or two summers respectively in polar latitudes around Antarctica. Extensive sea ice eventually blocked each voyages’ southern probes, although Bellingshausen, unknowingly at the time, saw the Antarctic continent. However, these attempts meant sea-ice and iceberg records from the early historical period were collected near simultaneously from around much of Antarctica. Here, these records are extracted from journals, analysed, and compared to each other and the modern satellite record of both forms of marine ice. They generally show an early historical period with a more northerly record of both forms of marine ice than normal for today, but to a geographically varying degree. However, the early historical period in the Pacific sector of the Southern Ocean saw marine ice generally within the range of modern observations for the same time of year, but the Weddell Sea and Indian Ocean marine ice, particularly on Cook’s voyage, then extended several degrees further north than in today’s extreme ice years.