Overview of conditions
Sea ice extent averaged over the month of June 2009 was 11.48 million square kilometers (4.43 million square miles). This was 420,000 square kilometers (162,000 square miles) above the record low for that month, which occurred in June 2006, and 700,000 square kilometers (270,000 square miles) below the 1979 to 2000 average.
Conditions in context
Through most of June, ice extent tracked close to two standard deviations below the long-term mean and just above the levels observed in 2007. By the end of June 2009, ice extent was 337,000 square kilometers (130,000 square miles) higher than extent at the end of June 2007.
During June, the Arctic Ocean lost a total of 2.05 million square kilometers (792,000 square miles) of ice, an average decline of 68,300 square kilometers (26,400 square miles) per day.
Figure 3. Monthly June ice extent for 1979 to 2009 shows a decline of 3.3% per decade. —Credit: National Snow and Ice Data Center
June 2009 compared to past Junes
Compared to previous Junes, ice extent in June 2009 was extremely close to the last two years, falling within 30,000 square kilometers (12,000 square miles) of the June extent in 2007 and 2008. The long-term trend indicates a decline of 3.3% per decade, an average of 40,100 square kilometers (15,500 square miles) of ice per year.
Figure 4. The map of sea ice concentration from AMSR-E from July 5, 2009 shows low ice concentrations in the Laptev Sea, where atmospheric temperatures have been particularly warm in the month of June. NASA AMSR-E data.—Credit: From National Snow and Ice Data Center courtesy IUP, University of Bremen, Germany
Warm conditions speed regional melt
In June, the Arctic saw warm temperatures over the Laptev Sea and the northern Beaufort Sea, while the Atlantic sector of the Arctic was slightly cooler than normal. The warm temperatures in the Laptev Sea corresponded to quickly declining ice concentrations in the area. The decline can be seen in sea ice concentration analyses produced at the University of Bremen using NASA Advanced Microwave Sounding Radiometer-Earth Observing System (AMSR-E) data. We expect this region to become largely ice-free in the next few weeks.
Figure 5. The map of sea level pressure (in millibars) from June 1 to 30, 2009 shows high pressure (red) over the northern Beaufort Sea and a weak low (purple) centered over Novaya Zemlya. —Credit: From National Snow and Ice Data Center courtesy NOAA/ESRL Physical Sciences Division
Southerly winds promote warmth
The warmth in the Laptev Sea is consistent with a pattern of southerly winds in these areas, which can be linked to the area of low atmospheric pressure centered just north of Novaya Zemlya Island. Note also the strong high-pressure cell (an anticyclone) over the northern Beaufort Sea.
This contrast between high and low pressure is broadly similar to the atmospheric circulation pattern that set up in 2007. In 2007, that pattern contributed to a significantly accelerated decline in ice extent during July, and a record minimum low in September. Will the same acceleration in ice melt occur this year? If so, a new record low minimum extent becomes more likely. So far, an acceleration has not been observed. As July progresses, the Arctic sun gets lower on the horizon, incoming solar energy decreases, and the chances of such a rapid decline become less likely.
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