Arctic sea ice extent arrives at its minimum

On September 19 and 23, Arctic sea ice appeared to have reached its seasonal minimum extent for the year, at 4.59 million square kilometers (1.77 million square miles). This ties 2018 with 2008 and 2010 for the sixth lowest minimum extent in the nearly 40-year satellite record. 
 

Please note that this is a preliminary announcement. Changing winds or late-season melt could still reduce the Arctic ice extent, as happened in 2005 and 2010. NSIDC scientists will release a full analysis of the Arctic melt season, and discuss the Antarctic winter sea ice growth, in early October.

Overview of conditions

On September 19 and 23, 2018, sea ice extent dropped to 4.59 million square kilometers (1.77 million square miles), tying for the sixth lowest minimum in the satellite record along with 2008 and 2010. This appears to be the lowest extent of the year. In response to the setting sun and falling temperatures, ice extent will begin expanding through autumn and winter. However, a shift in wind patterns or a period of late season melt could still push the ice extent lower.

The minimum extent was reached 5 and 9 days later than the 1981 to 2010 median minimum date of September 14. The interquartile range of minimum dates is September 11 to September 19. This year’s minimum date of September 23 is one of the latest dates to reach the minimum in the satellite record, tying with 1997. The lateness of the minimum appears to be at least partially caused by southerly winds from the East Siberian Sea, which brought warm air into the region and prevented ice from drifting or growing southward.

This year’s minimum extent ranked behind 2015 (fifth lowest), 2011 (fourth lowest), 2007 and 2016 (tied for second lowest), and 2012 (lowest). Moreover, the twelve lowest extents in the satellite era have all occurred in the last twelve years.

Conditions in context

This year’s minimum set on September 23 was 1.20 million square kilometers (463,000 square miles) above the record minimum extent in the satellite era, which occurred on September 17, 2012, and 1.63 million square kilometers (629,000 square miles) below the 1981 to 2010 average minimum extent.

Twelve lowest minimum Arctic sea ice extents (satellite record, 1979 to present)

Values within 40,000 square kilometers (15,000 square miles) are considered tied. The 2017 value has changed from 4.64 to 4.67 million square kilometers (1.80 million square miles) when final analysis data updated near-real time data.