Changes in Atlantic water properties: an important factor in the European Arctic marine climate

The advection of warm Atlantic water (AW) through the Nordic Seas and its transformation (cooling and freshening) is one of the most important climatological processes in the region. Time-series of hydrographic observations in the northern Nordic Seas and the Fram Strait region are presented and analysed. Significant variability in the properties of AW has been observed in recent years. A 15-year time-series of summer observations indicate positive trends in salinity and temperature and two 5–6-year cycles. The northward advance of AW in 2006 was an unprecedented event. The position of the warm-water tongue shifted more than 350 km to the north, and temperatures in the West Spitsbergen Current reached the highest values ever recorded. These changes in AW temperature, heat content, and northward transport had a strong influence on the oceanic climate and sea-ice conditions north of Svalbard. These oceanic signals led to environmental changes that confirm the primary role of the ocean in shaping the climate of the region.