Records when referring to an entire year rarely refer to a record extreme. For example, when they say that 2016 was the hottest year on record, they don't mean

Records when referring to an entire year rarely refer to a record extreme. For example, when they say that 2016 was the hottest year on record, they don't mean that the hottest day of the year was hotter than the hottest day of any other year. They mean that the average was hotter than the average for other years. I expect sea ice extent would be similar.