Arctic Sea Ice News 2006

During the crucial summer melting season, scientists monitor the condition of the Arctic sea ice for comparison to previous years. For more on the importance of sea ice and how scientists monitor it, please see our Frequently Asked Questions.

Please see our Resources for the Press, at right, for further details and information of interest to journalists.

Ongoing commentary and updates from NSIDC scientists

August 23, 2006 through October 3, 2006, we will post updates as events warrant. To view previous updates, scroll down. For automatic updates, see our RSS Feed.

Credit for content/image use:
National Snow and Ice Data Center

6 September 2006 [top]

Overview of current sea ice conditions
Current sea ice conditions are still below the long-term average and above last year's record. For more details, see below. Sea ice data are obtained from satellites; see Frequently Asked Questions for more about data sources.

Figure 1: Sea ice extent for September 5, 2006

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Current sea ice conditions: September 5, 2006

Figure 1 shows current sea ice extent. Compared to the last report, extent has declined only slightly. Over the past few days,  extent has hovered around 6 million square kilometers (2.3 million square miles).

The unusual polynya in the Beaufort sea is still present. A number of polynyas tend to form in the same place every year, perhaps the best-known being the “Northwater Polynya” in Baffin Bay. Such features are also common along the north coast of Canada. Often, such polynyas form because of upwelling of warm water to the surface. This could be possible here; however, it is more likely caused by atmospheric circulation forcing a local divergence of ice. We have never seen a large polynya in the Beaufort Sea, and it is not entirely clear how it formed.

White indicates areas where sea ice is present. Areas in blue are open ocean, while gray indicates land masses. The pink line shows the average ice extent for September, the end of the summer melt season. The September average is calculated from 1979 through 2000.

Figure 2: Summer melt season Arctic sea ice extent

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Current sea ice conditions in context

Figure 2  shows the updated timeline of sea ice conditions. The slowing of ice loss noted in the report, below, has continued.

If the sea ice were to stop shrinking now, it would probably be the 8th lowest of the 28-year satellite record. However, it is still premature to come to any conclusions. For example, looking back at 2005, it seemed that ice loss had ceased around the second week of September, only to decline again the next week.

Figure 3: August 2006 Arctic temperature anomalies

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Figure 4: August 2006 Arctic sea-level pressure anomalies

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August in review: atmospheric conditions

Figure 3 shows air temperature over the Arctic for August. As in past reports, values show anomalies (in degrees Celsius) compared to long-term average conditions.

We can now confirm that August broke the pattern of unusually warm conditions that had characterized the Arctic from January through July 2006 (see 23 August, below). Temperatures near the pole were actually slightly colder than average (1 to 2 degrees Celsius), inhibiting ice melt in this area. Temperatures along the Eurasian coast were slightly above average.

Figure 4 shows the average atmospheric pressure at sea level for August. The salient feature is a pronounced average low-pressure area just off the pole, shown in dark purple. While such a pattern is fairly common in the summer Arctic, the average low in August was especially strong. Air temperatures beneath such lows are typically colder than average; the results in Figure 3, above, fit this pattern.

Surface winds around the low-pressure system blow counterclockwise. The balance of forces on the ice, when the winds are blowing this way, promotes ice divergence. This spreads the ice over a larger area. Note that clockwise winds promote convergence, packing the existing ice into a smaller area.

The combination of cooler temperatures and counterclockwise winds helps explain the slower sea ice losses in August 2006 as compared to last year, when the central Arctic Ocean was not as stormy. Understanding year-to-year variations in storminess over the Arctic Ocean is a subject of ongoing research at NSIDC.

The NOAA Live from the North Pole Web cam offers photographs showing near-real-time conditions near the pole. The latest image shows low clouds and poor visibility, typical for this time of year. Perhaps conditions may clear in the near future; if so, the Web cam would provide good idea of sea ice conditions in the area.  

30 August 2006 [top]

Overview of current sea ice conditions
Current sea ice conditions are still below the long-term average and slightly above last year's record. For more details, see below. Sea ice data are obtained from satellites; see Frequently Asked Questions for more about data sources.

Figure 1: Sea ice extent for August 29, 2006



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Current sea ice conditions: August 29, 2006

Figure 1 shows current sea ice extent. Sea ice extent continues to decline as the melt season
progresses. The unusual polynya in the Beaufort Sea, noted in the previous report, has gotten somewhat larger. While the ice has retreated poleward of its September average in most places, it is still outside of the September average off the western part of Alaska. The strongest ice retreats since our last report are along parts of the Russian coast.

White indicates areas where sea ice is present. Areas in blue are open ocean, while gray indicates land masses. The pink line shows the average ice extent for September, the end of the summer melt season. The September average is calculated from 1979 through 2000.

Figure 2: Summer melt season Arctic sea ice extent

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Current sea ice conditions in context

Figure 2 shows current sea ice conditions. The rate of ice loss has slowed slightly compared to our last report. If this slowing were to continue, sea ice extent in 2006 would not set a new record low. However, conditions may change over the next few weeks.

Two factors help explain the slower ice loss compared to 2005. First, air temperatures in August have not been especially warm; in some areas, conditions have even been slightly cooler than normal. This contrasts with the unusual warmth from January through July (see last report, below).

Second, low atmospheric pressure, centered slightly off the North Pole, has dominated the area during August. Low pressure favors extensive cloud cover, which in summer moderates temperatures. Finally, the counterclockwise winds that dominate the low-pressure region tend to spread the ice over a larger area. However, the ice will then be present in lower concentrations, with more open water between floes.

We will post a full explanation of August atmospheric conditions in our next update.

23 August 2006 [top]

Overview of current sea ice conditions
Current sea ice conditions are below average and are closely tracking last year's record low. For more details, see below.

Sea ice data are obtained from satellites. See Frequently Asked Questions for more information on data sources.

Figure 1: Sea ice extent for August 22, 2006



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Current sea ice conditions: August 22, 2006

Figure 1 shows current sea ice extent. White indicates areas where sea ice is present. Areas in blue are open ocean, while gray indicates land masses. The pink line shows the average ice extent for September, the end of the summer melt season. The September average is calculated from 1979 through 2000.

We see that over most parts of the Arctic, the sea ice has already retreated poleward of where it should be for an average September. However, the projected sea ice minimum is still several weeks into the future. That said, the ice extent for August 22 is slightly greater than observed last year at the same time (see Figure 2). 2005 was the record minimum sea ice extent.

The Northwest Passage, through the channels of the Canadian Arctic Archipelago, is essentially clear. An unusual polynya, an irregularly shaped area of open water, has appeared north of Alaska in the Beaufort Sea.

Figure 2: Summer melt season Arctic sea ice extent

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Current sea ice conditions in context

As Figure 2 shows, current sea ice extent, shown in solid blue, is well below the average for 1979-2000, which is shown in solid gray. However, slightly more sea ice is present now than this time last year, indicated by the dashed green line.

Figure 3: 2000 to 2005 Arctic temperature anomalies



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Figure 4: 2005 Arctic temperature anomalies



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Figure 5: 2006 Arctic temperature anomalies (January to July)



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Warm temperatures contribute to ice loss

Unusually high air temperatures over the Arctic help to explain the ongoing decline of sea ice.

Why? First, the warmer Arctic is helping to melt more ice in summer, and inhibiting ice growth in the winter. Second, as we begin to lose the sea ice cover, the ocean releases more heat into the lower atmosphere. Put differently, the warmer Arctic leads to less sea ice, and the loss of sea ice contributes to a warmer Arctic.

Figure 3 shows surface air temperature anomalies from 2000 to 2005. The scale goes from red for temperatures strongly above average to blue/purple for temperatures strongly below average. These anomalies show temperatures compared to the average for
1968 to 1996.Temperatures from 2000 to 2005 were from 1 to 3 degrees Celsius (2 to 5 degrees Fahrenheit) higher than average. Note that there are essentially no areas with unusually low temperatures.

Figure 4 shows temperature anomalies for only 2005, which was the record low year for sea ice. For the globe as a whole, 2005 was tied for the warmest year on record. The year 2005 was especially warm in the Arctic, with temperatures 2 to 4 degrees Celsius (4 to 7 degrees Fahrenheit) above normal.

Figure 5 shows that the warm trend has continued in 2006, which does not bode well for the sea ice.

Winds blow the ice away

Strong winds in Fram Strait in September of 2005 seem to have contributed to this summer's declining sea ice.

Fram Strait, between northern Greenland and Svalbard, is the primary region where sea ice flows out of the Arctic Ocean and into the North Atlantic. This transport is strongly determined by the speed and direction of the wind. As pointed out by our colleague, Dr. Ron Kwok at the Jet Propulsion Laboratory in Pasadena, California, especially strong winds in Fram Strait during September 2005 appear to have "flushed" part of the older, thicker ice out of the Arctic. Hence, in spring of 2006, the melt season started with thinner ice, which is more apt to melt during the summer.