Sea Ice Extent

July's Northern Hemisphere Sea Ice extent
July's Northern Hemisphere
Sea Ice Extent plot

According to the National Snow and Ice Data Center (NSIDC), the Northern Hemisphere sea ice extent — which is measured from passive microwave instruments onboard NOAA satellites — averaged for July 2011, was 7.92 million square kilometers (3.06 million square miles), 21.55 percent below the 1979-2000 average. This is the smallest July Arctic sea ice extent since records began in 1979 — 210,000 square km (81,000 square miles) smaller than the previous record July low set in 2007. July 2011 marks the 15th the consecutive July and the 122nd consecutive month with below-average Arctic sea ice extent. July Arctic sea ice extent has decreased at an average rate of 6.8 percent per decade.

During the first half of July, Arctic sea ice extent declined rapidly, dipping below the extent from the same period in 2007 — the year the record low sea ice minimum extent was set. However, weather conditions near the end of the month slowed the melting, and on July 31st, the Arctic ice extent was 6.79 million square kilometers (2.62 million square miles) — slightly larger than the same day in 2007. For the month of July, most regions of the Arctic experienced below-average ice coverage, with the exception of the East Greenland Sea, where near-average ice coverage was observed.

July's Southern Hemisphere Sea Ice extent
July's Southern Hemisphere
Sea Ice Extent plot

The July 2011 Southern Hemisphere sea ice extent was 0.54 percent below the 1979-2000 average. This is the 12th smallest (22nd largest) July Southern Hemisphere sea ice extent on record. The July 2011 Antarctic sea ice extent was significantly smaller than the July 2010 extent, which was the largest on record at 4.84 percent above average. July Antarctic sea ice extent has increased at an average rate of 0.8 percent per decade, although there is considerable interannual variability. During July, Antarctic sea ice continued its annual growth cycle, after reaching its annual minimum extent at the end of February.

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, Monthly Global Snow and Ice Report for July 2011, published online August 2011, retrieved on May 6, 2024 from https://www.ncei.noaa.gov/access/monitoring/monthly-report/global-snow/201107.