I wouldn't pay too much attention to the ice against the Siberian coast - it's thin, covers a relatively small area, and they don't refer to it in the text. Probably best interpreted to mean there will still be some isolated bits in the east Siberian sea which don't have time to melt? Other than that the final pack looks about right, with a thin strip of thicker ice against Greenland/Canada and not much else. It will be wrong, of course, but it won't be very wrong