Climatic variability of the ice extent of the Barents Sea and its individual areas

Abstract

The ongoing decrease in the ice coveren is one of the main consequences of global climate change. The Barents Sea, as part of the North European basin, is an area that is one of the first to react to these changes. According to the AARI database, before the start of the current century the ice extent in the winter season varied from 600·103 km2 to 900·103 km2 in different years, while over the past 20 years the lower border has dropped to 350·103 km2. At the same time, the ice extent in the summer season has decreased more than 3 times. The aim of the article is to study the statistical structure of the longterm variability of the ice extent on the basis of the latest data, in order to identify the patterns of change characteristic of individual areas of the Barents Sea over the past decades. The main research methods include basic statistics, linear trend, stationary assessment, autocorrelation and the correlation coefficient. The work contains numerical estimates of the trend component for all the parts of the water area. The maximum contribution of the linear trend is due to the northeastern region and comprises 63 %. The maximum seasonal fluctuations are characteristic of the southeastern region, with almost complete freezing in winter (up to 99 %, as in the northeast) and complete clearing in summer and the absence of old ice. The same area has the least connection with the other parts (R less than 0.25) and the variability of its characteristics depends to a greater extent not only on the circulation of cold Arctic waters and the entry of warm Atlantic water, but also on river runoff. The north-eastern region is characterized by the capacity for retaining the “memory” of the previous state for more than 5 years, which indicates the highest inertia of the factors making for the variability of the ice extent. The speed of reducing the ice coveren because of melting is estimated at 1.76·103 km2/month, while the rate of increase in the ice extent as a result of ice growth is estimated at 1.26·103 km2/month. Accordingly, the ice melts faster than it has time to grow, which leads to a decrease in the ice extent.