There is a lot less thick ice in the Arctic than there was in 1979. Alarmists mindlessly spew that it melted in the summer sun, but that is incorrect.
Most multi-year sea ice is lost during the winter, not the summer. Strong winter winds blow it out into the North Atlantic, where it quickly melts. Most of the thick ice was lost during the winters between 1988 and 1996, due to unusual winds.
This coincided with a period of high ENSO.