A changing Arctic seasonal ice zone: Observations from 1870-2003 and possible oceanographic consequences

Changes in the extent of seasonal ice were investigated using historical and satellite observations for the period 1870–2003. The seasonal ice zone (SIZ) has been gradually expanding since 1870, with a marked acceleration over the past three decades, and has migrated north to encompass all peripheral Arctic seas. The expansion of the SIZ may be increasing the salinity of the upper Arctic Ocean, consistent with recent observations. The migration of the SIZ over continental shelves may also be enhancing the formation rate and salinity of Arctic deep waters, which are subsequently advected to the convective region of the Greenland‐Iceland‐Norwegian Sea, thereby influencing the formation of North Atlantic deep waters and related global thermohaline circulation.