The summer period is distinguished by a general decrease of the sea ice in the Russian Arctic. However, difficult ice conditions may form in the local areas and some sea regions during the autumn-winter period.
“Rapid reduction of the ice coverage in the Arctic Ocean results directly from the global temperature increase and climate change. Increase in the clearwater areas during the summer season has positive economic effect: more ships can sail across the Northern Sea Route without icebreakers, which makes a positive impact on the increase of the freight flow. But for the natural climate system, an increase in the clearwater areas in the summer results in heat accumulation in the ocean. This means that nature itself is exacerbating the warming trend. At the same time, analysis of the data over a long period of regular observations suggests that the warming factors in Arctic latitudes sharply intensified in early 2000s show a slowdown in recent years. Rising temperatures, shrinking ice cover and other climate change factors tend to stabilise,” said Alexander Makarov, Director of the Arctic and Antarctic Research Institute.
In 2021, advection of warm air masses and positive mean monthly air temperature anomalies prevailed in the polar region. The mean annual temperature changes in the polar region were 2.9°С above the norm, which was 1.1°С lower than in 2020.
Positive temperature anomalies were observed along the Northern Sea Route of the Arctic seas of Russia. The largest changes were observed in the Laptev and Kara Seas, and the smallest – in the Chukchi and East Siberian Seas. Compared to 2020, the mean air temperature along the Northern Sea Route decreased by 2.9 °С – from 4.9 °С in 2020 to 2.0 °С in 2021.
Changes in the Atlantic water temperature in the Arctic Ocean during the reporting period fully correspond to the values of the previous year, which shows that there is neither a positive nor a negative temperature trend. For the first time for the last eight years, there was detected decrease by 0.13°С of the maximum temperature of the Atlantic waters.
The trend towards a significant reduction of the ice coverage in the Arctic Ocean preserves. Over the past 50 years, the ice area in the winter season has decreased by 700 thousand square kilometres, and in the summer one – by 2.7 million square kilometres, which is larger than the size of Greenland island.
At the end of the winter season, ice thickness in some coastal areas, for example, in the southwestern part of the Kara Sea, in the area of Novosibirsk islands and in the coastal central part of the East Siberian Sea, was close to the mean multiyear values, growing up to 150-200 cm. This is more than during the previous years, and it is associated with the overall air temperature decrease in the winter season.
The ice area estimated for the end of the increasing period (early May) and the end of the breakup period (early October) is 13.5 and 5.1 million sq. km, respectively. The ice volumes in the Arctic Ocean calculated for these dates amount to 24.0 and 5.8 thousand cubic km. Thus, the decrease in ice area and the ice volume during the summer season amount to 8.4 mln sq km and 18.2 thousand cubic km, respectively.
Development of ice conditions in 2021 preserved the last decade’s trend. Following the abnormally easy development of ice conditions in 2012, we observed in all subsequent years, including 2021, development of a moderately low ice coverage (by 5-10 percent less than the mean multiyear values) throughout the year, except for the summer season. During the summer period, the ice coverage significantly reduced and light ice conditions formed (the ice coverage anomaly was 25–30 percent less than the long-term mean values). However, in the autumn season (October-December), the ice areas increase rapidly, and the sea is covered with young ice literally in 10-20 days.
The late start of ice formation in the autumn season, and, at the same time, large intensity of its development in the 2020 November-December, resulted in the ice cover rapid increase, but slow growth of its thickness. The area of fast ice (the fixed ice near the coasts of the continents and islands) in all the Russian Arctic seas was less than the mean multiyear values, except for the fast ice in the western part of the East Siberian Sea. In mid March, the total area of fast ice in the Russian Arctic seas was 500,000 sq. km, compared to the norm of 586,000 sq. km, which was 15 percent less than the multiyear average. At the same time, in the western part of the East Siberian Sea, fast ice was developed by 25 percent more than the norm.