As we continue to progress into the summer months, we begin to monitor and watch ice melting across the Arctic. More sunlight and warmer conditions help melt Arctic ice each year from about May through early September. Then, around October each year, sea ice extent begins to grow again as the winter months approach. In 2012, sea ice maximum occurred on March 20, and afterwards Arctic sea ice underwent a loss of 11.83 million square kilometers (4.57 million square miles), the largest Arctic summer ice loss since satellites began monitoring sea ice continuously in 1979. In June 2013, ice extent across the Arctic was below average once again, although nowhere close to the record ice loss seen last year at this time.
According to the National Snow and Ice Data Center (NSIDC) in Boulder, Colorado, average sea ice extent for June 2013 was 11.58 million square kilometers, or 4.47 million square miles. Overall, this means that sea ice extent is approximately 310,000 square kilometers (120,000 square miles) below the 1981 to 2010 average (the new baseline period) of 11.89 million square kilometers (4.59 million square miles).
The ice was melting more slowly than at this time last year, but it started to melt faster around the end of June, 2013. Temperatures across the region were slightly below average as low pressure was centered over the Arctic throughout June. This atmospheric pattern was almost opposite of what we saw last year when the record-breaking melt occurred across the Arctic. The ice extent dropped an average of 70,300 square kilometers (27,000 square miles) per day through the month of June, slightly higher than the 1981 to 2010 average. Since record keeping began in 1979, June 2013 is ranked as the 11th lowest sea ice extent for the month of June.