This study presents a comparison of the sea-ice cover of the whole Arctic Ocean with two arctic sectors of different morphology: the Greenland Sea, as a typical “open sea”, and the Beaufort Sea, as a typical “closed sea”. The study refers to the period January 1996–December 2015 and makes use of the Arctic sea-ice concentration data set produced, on a daily basis, by the Institute of Environmental Physics of the University of Bremen. From the whole Arctic data set, two subsets, covering the Greenland Sea and the Beaufort Sea, were extracted. The extent of sea-ice cover was obtained by the sea-ice area (SIA) parameter, which was computed according to the conventional NASA method. Our analysis shows that the strong summer decline of the Arctic SIA in the last 20 years is not observed in the Greenland Sea (the trend of SIA minimum values is $$0.7 \pm 2.0{\rm{ }}{10^3}\,{\rm{k}}{{\rm{m}}^{\rm{2}}}\,{\rm{yea}}{{\rm{r}}^{ - 1}}$$) while it is even greater in the Beaufort Sea.