Bellingshausen Sea ice extent recorded in an Antarctic Peninsula ice core

Annual net accumulation ( A n ) from the Bruce Plateau (BP) ice core retrieved from the Antarctic Peninsula exhibits a notable relationship with sea ice extent (SIE) in the Bellingshausen Sea. Over the satellite era, both BP A n and Bellingshausen SIE are influenced by large‐scale climatic factors such as the Amundsen Sea Low, Southern Annular Mode, and Southern Oscillation. In addition to the direct response of BP A n to Bellingshausen SIE (e.g., more open water as a moisture source), these large‐scale climate phenomena also link the BP and the Bellingshausen Sea indirectly such that they exhibit similar responses (e.g., northerly wind anomalies advect warm, moist air to the Antarctic Peninsula and neighboring Bellingshausen Sea, which reduces SIE and increases A n ). Comparison with a time series of fast ice at South Orkney Islands reveals a relationship between BP A n and sea ice in the northern Weddell Sea that is relatively consistent over the twentieth century, except when it is modulated by atmospheric wave patterns described by the Trans‐Polar Index. The trend of increasing accumulation on the Bruce Plateau since ~1970 agrees with other climate records and reconstructions in the region and suggests that the current rate of sea ice loss in the Bellingshausen Sea is unrivaled in the twentieth century.