Global Snow and Ice - September 2018


Sea Ice Extent

September 2018 Sea Ice Extent
1981-2010
Anomaly
Trend
(per decade)
Rank
(out of 40 years)
Records
million km2 million mi2 Year(s) million km2 million mi2
Northern Hemisphere 4.71 1.82 -26.52% -12.48% Largest 34ᵗʰ 1980 7.67 2.96
Smallest 7ᵗʰ 2012 3.57 1.38
Southern Hemisphere 17.88 6.90 -3.30% +0.54% Largest 39ᵗʰ 2014 19.76 7.63
Smallest 2ⁿᵈ 1986 17.68 6.83
Globe 22.59 8.72 -9.28% -2.81% Largest 40ᵗʰ 1980 26.49 10.23
Smallest 1ˢᵗ 2018 22.59 8.72

Data Source: National Snow and Ice Data Center (NSIDC). Period of record: 1979–2018 (40 years)

According to the National Snow and Ice Data Center (NSIDC), the Northern Hemisphere (Arctic) sea ice extent — which is measured from passive microwave instruments onboard NOAA satellites — averaged for September 2018 was 4.71 million square km (1.82 million square miles), 1.70 million square km (656,000 square miles), or 26.5 percent, below the 1981-2010 average. This was the seventh smallest September Arctic sea ice extent on record. This was also 1.14 million square kilometers (440,000 square miles) above the record low recorded for September 2012. The ice contracted at a faster rate early in September, reaching its annual minimum extent on the 19th and again on the 23rd. The double minimum date was due to ice melting in parts of the East Siberian, Laptev, and Chukchi Seas while it was expanding in Beaufort, Kara, and Barents Seas. September Arctic ice extent is decreasing at an average rate of 12.5 percent per decade.

The Arctic sea ice reached its annual minimum extent on September 19th and again on the 23rd at 4.59 million square km (1.77 million square miles). This tied with 2008 and 2010 for the sixth lowest minimum extent in the 40-year satellite record and was 1.20 million square km (463,000 square miles) larger than the record set in 2012. The minimum extent occurred five and nine days later than the 1981-2010 median date. September 23rd is one of the latest dates on record for the minimum to occur.

The September Southern Hemisphere sea ice extent was 17.88 million square km (6.90 million square miles), which was 610,000 square km (240,000 square miles), or 3.3 percent, below the 1981-2010 average. This was the second smallest September Southern Hemisphere sea ice extent on record with only the September extent being smaller in 1986 at 17.68 million square km (6.83 million square miles). Antarctic sea ice expanded erratically during September with ice loss during the first half of the month and ice expanding the second half of the month, reaching the annual maximum extent in early October at the fourth smallest maximum extent. Additional information on the annual maximum will be available in the October report. Southern Hemisphere September sea ice extent is increasing at an average rate of 0.5 percent per decade, with substantial inter-annual variability.

For further information on the Northern and Southern Hemisphere snow and ice conditions, please visit the NSIDC News page.

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Citing This Report

NOAA National Centers for Environmental Information, State of the Climate: Global Snow and Ice for September 2018, published online October 2018, retrieved on November 14, 2018 from https://www.ncdc.noaa.gov/sotc/global-snow/201809.

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