The extent of sea ice around Antartica and the Arctic should be a sensitive indicator of climatic change at the poles. In his Perspective, Wolff highlights the report of Curran et al ., who have compared a potential chemical proxy for sea ice extent from an ice core with satellite records for sea ice extent in the nearby ocean. Finding good agreement, the authors extended the proxy record to 1840. They conclude that sea ice was stable from 1840 to 1950, but has decreased sharply since then. Wolff warns that the results do not seem to echo any clear temperature trend from meteorological stations in this region. Nevertheless, this intriguing evidence for recent climate change calls for rapid investigation of similar data from around Antarctica.