Arctic sea ice 2013. Observations before the melt season
Written by Brian Hansen og Susanne Hanson
18th June, 2013
DMI, Centre for Ocean and Ice
- The summer sea ice extent is almost 30% smaller than in the early 1980’s. The winter extent has also declined, with approximately 10 % having disappeared
- The extent of multi-year ice, and thereby the thickness of the sea ice, has also been significantly reduced.
- The ice extent at the end of the melting season (September) in 2012 set a new record: it was the lowest extent observed since the beginning of satellite surveys in 1979. Compared to the average extent over the period 1979 to 2000, the 2012 extent was reduced by 49%.
- The ice extent in May 2013 followed the evolution from the previous years and was below the average for the period 1979 to 2000. Compared to this average, there was about 500,000 km2 less sea ice in May 2013.
The Arctic sea ice in the later years
The sea-ice extent at the end of the melting season in 2012 set a new record: It was the lowest extent observed since the beginning of satellite surveys in 1979. Compared to the average extent over the period 1979 to 2000, the 2012 extent was reduced by 49% (1).
Since the 1980's, the summer minimum of the Arctic sea-ice area has been reduced by almost 30%, as seen over the past few years. The ice-covered area in summer is decreasing at twice the rate for the winter area. Nevertheless, the winter area is also decreasing. Here, almost 10% has disappeared. A trend line based on satellite data from OSISAF shows that the winter sea-ice cover is being reduced by 43,000 km2 per year and the summer ice cover by 98,000 km2 per year (2). This has the consequence that an increasing amount of the Arctic sea ice is new, thin, first-year ice.
The total volume of ice is thus decreasing even faster than can be seen from satellites.
Observations in the first months of 2013
The mean temperature in the Arctic north of 80° N in the winter of 2013 and in the earliest spring months has generally been normal, with fluctuations both above and below the climatological mean. In the latter half of April and in early May, there was a small temperature rise, but from then on until mid-June, the mean temperature has remained under the climatological mean. The temperature has not yet risen over the melting point, as it did by this time in 2012.
The ice extent for winter and spring 2013 until mid-June reflects the temperature evolution.
It follows the trend from previous years and is 500,000 km2 below the average for the period 1979 to 2000. The large reduction in 2012, which began about June 1, has not yet been seen in 2013. Although the ice extent is low, its extent in mid-June 2013 is almost 500,000 km2 larger than on the same date in 2012. In round numbers, it is halfway between the mean ice extent and the record minimum year of 2012.