Arctic sea ice extent averaged for July was the second lowest in the satellite record, after 2007. After a slowdown in the rate of ice loss, the old, thick ice that moved into the southern Beaufort Sea last winter is beginning to melt out.

About the data. Figure 1. Arctic sea ice extent for July 2010 was 8.39 million square kilometers (3.24 million square miles). The magenta line shows the 1979 to 2000 median extent for that month. The black cross indicates the geographic North Pole. Sea Ice Index data —Credit: National Snow and Ice Data Center

High-resolution image Overview of conditions Average ice extent for July was 8.39 million square kilometers (3.24 million square miles), 1.71 million square kilometers (660,000 square miles) below the 1979 to 2000 mean, but 260,000 square kilometers (100,000 square miles) above the average for July 2007, the lowest July in the thirty-two-year satellite record. Stormy, cloudy, and relatively cool weather persisted through the month, which helped slow the rate of ice loss. The daily rate of decline for July was 77,000 square kilometers (29,700 square miles) per day, close to the 1979 to 2000 average of 84,400 square kilometers (32,600 square miles).

Figure 2. The graph above shows daily Arctic sea ice extent as of August 3, 2010. The solid light blue line indicates 2010; dashed green shows 2007; solid pink shows 2006, and solid gray indicates average extent from 1979 to 2000. The gray area around the average line shows the two standard deviation range of the data. Sea Ice Index data —Credit: National Snow and Ice Data Center

High-resolution image Conditions in context Cool, stormy weather this July has made it less likely that the upcoming 2010 sea ice minimum will set a new record. It would take a very unusual set of conditions in August to create a new record low. If the daily rate of decline this August follows the average August rate of decline for 1979 to 2000, the daily sea ice minimum in September would be 5.00 million square kilometers (1.93 million square miles), considerably higher than the record minimum of 4.13 million square kilometers (1.59 million square miles) observed for September 16, 2007. A daily rate of decline identical to 2007 would yield a September minimum of 4.43 million square kilometers (1.71 million square miles); while daily decline rates similar to 2008 (the largest ever observed for August), would yield a September minimum of 4.08 million square kilometers (1.58 million square miles). If the daily rate of decline is similar to 2006, the slowest in recent years, the minimum would be 5.27 million square kilometers (2.03 million square miles).



Figure 3. Monthly July ice extent for 1979 to 2010 shows a decline of 6.4% per decade. —Credit: National Snow and Ice Data Center

High-resolution image July 2010 compared to past years Ice extent for July 2010 was the second lowest in the satellite record for the month. The linear rate of decline of July ice extent over the period 1979 to 2010 is now 6.4% per decade.