Sea Ice and Freshwater Ice Assessments

2012 Arctic Sea Ice

Michael Key

University of Wisconsin-La Crosse

25 June 2013

On September 16, 2012, satellite imaging showed Arctic sea ice was at its lowest extent since 1979, plunging past the previous record low of 4.17 million sq km set in the summer of 2007. The minimum extent in 2012, recorded at 3.41 million sq km, is well below the 1979-2010 average of 6.14 million sq km and is the lowest extent from the past six years. The six-year period of 2007-2012 is significant because it marks the six lowest seasonal ice extents in the satellite record (NSIDC).

The month of June experienced a loss of sea ice extent averaging about 170,000 sq km/day. The first half of August 2012 saw extreme losses of 100,000-150,000 sq km of ice per day compared to the month’s average extent loss of ~60,000-70,000 sq km/day. The decrease in ice extent began stabilizing slightly around mid-August.

Interestingly, air temperatures and other weather conditions over the Arctic were less conducive to ice loss in 2012 than in 2007, but a lengthy and powerful storm system over the Chukchi Sea contributed to the mechanical disintegration of large sections of thin, first-year ice. The storm would likely have had a significantly smaller impact on ice loss if the extent were still composed of thicker multi-year ice, which is stronger than the comparatively weak seasonal ice that has become more prevalent in recent years.

Continuing into the winter of 2012, average sea ice extent for the month of December was only 12.2 million sq km, approximately 1.16 million sq km below the 1979-2000 average, making it the second lowest extent for the month on satellite record. Parts of the Kara and Barents seas remained ice-free through the end of the month. Arctic sea ice gain in December was limited to 2.33 million sq km, which is also far below the 1979-2000 average for the month.

Recent research suggests that the steady decline of sea ice extent could play a role in snowier winters and cooler spring times in the northern hemisphere (cf., Tang et. al., 2013). Rising air and water temperatures have an effect on atmospheric circulation, including changes to the jet stream, which plays a vital role in global weather.

Sources

• NSIDC Sea Ice News
• Tang, Q., X. Zhang, X. Yang, and J. Francis, 2013, Cold winter extremes in northern continents linked to Arctic sea ice loss , Environ. Res. Lett., 8, doi:10.1088/1748-9326/8/1/014036.