Recent Change—Sea Ice

Abstract

Sea ice conditions in the Baltic Sea have been systematically monitored for more than 100 years. All sea ice-related parameters display large interannual variability, but a change towards milder ice winters has been observed over the past 100 years: in particular, the annual maximum ice extent has decreased and the length of the ice season has become shorter. There is no correlation between consecutive ice seasons because the thermal memory of the Baltic Sea is only 2–3 months. Interannual variabilityVariabilityin sea ice conditions is principally driven by the large-scale atmospheric circulation, described by the North Atlantic Oscillation. In addition to a tendency towards milder winters, the occurrence of severe ice winters has also decreased considerably over the past 25 years.