The chart shows the time series for the five lowest years of September Arctic sea ice extent.

2020 came in second

https://nsidc.org/data/seaice_index/images/daily_images/N_iqr_timeseries.png

This is only the second time in the 40 years we have had satellite monitoring of sea ice that the minimum dropped below 4 million sq kilometers.

In the first week of September, sea ice extent took a sharp downward turn, exceeding the pace of decline for any previous year during that period, and placing the 2020 sea ice minimum firmly as second lowest—after 2012—in the 42-year continuous satellite record. Pulses of warm air from north-central Siberia are responsible for the late downward trend. Sea ice decline has slowed in the past few days, and the annual minimum is imminent.