Documented record · well documented
Arctic Ocean (basin-wide)
September minimum sea-ice extent · Arctic
The National Snow and Ice Data Center recorded an Arctic September minimum extent of about 3.39 million km² — the lowest in the satellite record, which begins in 1979.
Why a record is measured against the place
A number on its own says very little. 3.39 million km² would be unremarkable in one climate and unthinkable in another. What makes a record matter is its distance from what that place, at that time of year, has historically produced — its own normal.
Not Normal expresses that distance in standard deviations (σ) from a thirty-year baseline. Two σ above normal is reached in roughly 1 year in 44 under the baseline climate; four σ above, roughly 1 year in 32,000.
Modelled demonstration series · not observed data
The same place on the field
Not Normal carries a modelled 75-year series for Arctic Ocean (basin-wide) (September minimum sea-ice extent) that demonstrates the reasoning above. It is synthesised from published climatology, not observed, and is kept apart from the documented record on this page.
The season here
September is when Arctic ice reaches its annual minimum — the number that summarises how much survived the melt season.
Other documented records
Open Arctic Ocean (basin-wide) on the field →