IS THE ARCTIC-OCEAN WARMING

Recent high-quality hydrographic measurements in the Arctic Ocean have revealed a warming of up to 1 K of the Atlantic Layer when compared w ith Russian climatologies of the 1940s to 1970s. About half of this wa rming can be attributed to the different methods by which the two data sets were obtained: the climatologies are based on discrete bottle da ta in the vertical and necessarily involve smoothing in space and time , whereas the modern, quasi-synoptic data are from continuously record ing conductivity-temperature-depth sondes and give much better resolut ion in the vertical. Modern surveys also focused more on boundary curr ent regimes where narrow warm bands of Atlantic Water are present. The remainder of the warming detected can be explained with the following physical arguments: (1) an increased inflow of Atlantic Water in the early 1990s and (2) a higher temperature of this inflowing water. Temp erature time series in the Barents Sea since the beginning of this cen tury suggest that the warming of the early 1990s is not a long-term cl imate signal but, rather, is related to the inherent natural variabili ty of the system with timescales of decades.