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Preliminary Conclusions Summarizing the major preliminary results of this study we conclude that: (1) Relative sea level monthly data from the 71 tide gauges in the Barents, Kara, Laptev, East Siberian and Chukchi Seas have been analyzed in order to estimate the rate of sea level change and major factors responsible for this process in the Arctic Ocean. (2) The Arctic Ocean sea level time series have well pronounced decadal variability which corresponds to the variability of the North Atlantic Oscillation index. Because of the strength of this variability and the relatively short sea level time series, our assessments of sea level trends remain somewhat uncertain. In spite of this limitation, we have employed statistical methods together with numerical models and estimated the contributions of various factors to the observed sea level change. By subtracting the influence of these factors from the observed regional rate of sea level rise we have been able to estimate the rate of sea level rise due to increase of the global ocean mass that is presumably due to the melting of land ice. (3) During the period 1954-1989 the average rate of relative sea level rise over the seas of the Russian Arctic has been 0.185 cm/year This is within range of the rate that has previously been inferred using tide gauge data for the global ocean as a whole (IPCC, 2001). It is also essentially the same as the rate for the Global Ocean recently inferred by Peltier (2001). (4) In the Arctic, the contribution to the observed rate of sea level rise from the steric effect is 0.064 cm per year. This is smaller than the rate of ocean thermal expansion estimated for the global ocean in IPCC (2001). In the Arctic Ocean, changes in salinity are more important for sea level variability than changes in temperature, and the combination of freshening of the Arctic Seas with warming and salinization of the Atlantic layer therefore leads to the rise of sea level along coastlines and the fall of sea level in the central parts of the Arctic Basin. (5) The contribution of the inverse barometer effect to the Arctic Ocean sea level rise is 0.056 cm per year. This is the highest rate of sea level rise among any of the estimates of this factor presented in IPCC (2001) for various regions. (6) The estimated rate of sea level rise due to the effect of wind is 0.018 cm per year, but it varies significantly from region to region. In the Arctic, this effect is due to the gradual decrease of the sea level atmospheric pressure over the Arctic Ocean and therefore to the more strongly cyclonic atmospheric circulation. (7) The contributions of river runoff, evaporation and precipitation to sea level change in the Arctic Ocean are very small and their cumulative effect is negligible. On the other hand, the P-E estimates over the Arctic Ocean are less accurate than the other investigated factors. (8) The residual term of the sea level rise balance assessment, 0.048 cm per year, may be due to the increasing of the Arctic Ocean and global ocean mass associated with melting of ice caps and small glaciers and with adjustments of the Greenland and Antarctica ice sheets to the observed climate change. |