Satellite records go back to 1979 [https://www.theguardian.com/world/2020/oct/22/alarm-as-arctic-sea-ice-not-yet-freezing-at-latest-date-on-record https://www.t

Satellite records go back to 1979 [https://www.theguardian.com/world/2020/oct/22/alarm-as-arctic-sea-ice-not-yet-freezing-at-latest-date-on-record https://www.theguardian.com/world/2020/oct/22/alarm-as-arcti...], but there appear to be ground based observations from earlier years that corroborate the abnormality of the current year.