Twentieth century sea-ice trends in the Ross Sea from a high-resolution, coastal ice-core record

We present the first proxy record of sea‐ice area (SIA) in the Ross Sea, Antarctica, from a 130 year coastal ice‐core record. High‐resolution deuterium excess data show prevailing stable SIA from the 1880s until the 1950s, a 2–5% reduction from the mid‐1950s to the early‐1990s, and a 5% increase after 1993. Additional support for this reconstruction is derived from ice‐core methanesulphonic acid concentrations and whaling records. While SIA has continued to decline around much of the West Antarctic coastline since the 1950s, concurrent with increasing air and ocean temperatures, the underlying trend is masked in the Ross Sea by a switch to positive SIA anomalies since the early‐1990s. This increase is associated with a strengthening of southerly winds and the enhanced northward advection of sea ice. Key Points Sea ice in the Ross Sea was stable between the 1880s and 1950s After 1950, sea ice area in the Ross Sea began to decline An increase from the 1990s onward is related to changing atmospheric circulation