Sea Ice Extent

August 2013Sea Ice ExtentAnomaly
per decade
(35 years)
million km²million mi²Year(s)million km²million mi²
Northern Hemisphere6.012.32-6.53%-11.51%Largest30th19838.193.16
Southern Hemisphere18.667.20+4.60%+0.90%Largest1st201318.667.20

Data Source: National Snow and Ice Data Center (NSIDC). Period of record: 1979–2013 (35 years)

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 August 2013 was 6.09 million square km (2.35 million square miles), 15.65 percent below 1981-2010 average, and the sixth smallest August Arctic sea ice extent on record. The sea ice extent during August 2013 was 1.38 million square km (533,000 square miles) larger than the record low monthly extent of August 2012. Despite the below-average Arctic sea ice extent, this was the largest August extent since 2009. Over the course of the month, the rate of ice loss was slightly faster than average. August marks the last full month of Arctic sea ice loss, with the annual sea ice minimum and the beginning of the growth season typically occurring in mid to late September. Over the long-term, the Arctic is losing August sea ice at an average rate of 10.66 percent per decade. Most regions of the Arctic experienced below-average sea ice during the month, with the exception of the East Siberian Sea, which had near-average ice coverage.

The August 2013 Southern Hemisphere sea ice extent was 18.92 million square km (7.31 million square miles), 4.47 percent above the 1981-2010 average. This marked the largest August Antarctic sea ice extent on record, surpassing the previous record large August extent of 18.85 million square km (7.28 million square miles) that occurred in 2010. August Southern Hemisphere sea ice extent is increasing at an average rate of 0.77 percent per decade, with substantial interannual variability.

When combining the Northern Hemisphere and Southern Hemisphere sea ice extents, the globally-averaged sea ice extent during August was 25.01 million square km (9.66 million square miles). This was 1.26 percent below the 1981-2010 average and the 13th smallest global August sea ice extent since records began in 1979 and the largest August global sea ice extent since 2004.

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

[ top ]

Citing This Report

NOAA National Centers for Environmental Information, Monthly Global Snow and Ice Report for August 2013, published online September 2013, retrieved on July 20, 2024 from