Sea ice extent in the Barents Sea and Fram Strait

Last updated 7 May 2022

It is important to monitor the extent of sea ice because it is vital for the climate in the Arctic and globally, and because it sets important limits for the ecosystems in the Arctic. The sea ice extent in the Barents Sea and the Fram Strait is presented here. The extent in April is presented because it is usually at its maximum then, and in September, as that is when it is usually at its minimum. The data presented here are derived from satellite monitoring, which began in 1979.

Status and trend

Many scientific publications document the decrease in the sea-ice extent in the Arctic, and many studies have shown that the most dramatic changes have been in the Russian part of the Arctic, particularly in the Barents Sea. The sea ice extent in the Barents Sea is calculated in a box delimited by 72°N and 82°N and longitudes 10°E and 60°E. In the Fram Strait, it is calculated in a box delimited by 70°N and 82°N and longitudes 20°W and 15°E.

Barents Sea

In most years, the maximum extent of sea ice in the Barents Sea is in April, and the minimum in September. The minimum and maximum months vary somewhat more in the Fram Strait, but MOSJ has chosen to display the same months here as for the Barents Sea.

The Barents Sea is characterized by great variation from year to year. The main development in the ice extent during the monitoring period has been a clearly negative trend. Based on a least-squares linear regression, the rates of decadal decrease in April and September were -9.8% and -17.7%, respectively. The time series (1979–2021) for the ice extent in April shows 5 years (1979, 1981, 1987, 1998 and 2003) with distinctly high values and 7 (2006, 2007, 2008, 2012, 2015, 2016 and 2021) with distinctly low values. The minimum extent in April was in 2016, and in 2015 and 2021 were the second and the third lowest extent, respectively.

In September, there are 5 years (1982, 1989, 1993, 2003 and 2014) when the ice extent in the Barents Sea was particularly large and 11 years (1979, 1984, 1996, 2001, 2004, 2011, 2012, 2013, 2018, 2020 and 2021) when it was especially small. The greatest extent of sea ice throughout the period was measured in April 1981 and the least in September 2013 and 2020 (practically the same values). September 2021 was the second lowest sea ice extent in the Barents Sea since 1979.

Fram Strait

The ice extent in the Fram Strait also varies greatly from year to year. Both April and September show a declining trend during the monitoring period. The year when the ice extent was at its maximum in April, 1986, was 2 years after a marked decrease in the April extent in 1984. Since then, the pattern has generally been that years with an above average ice extent succeed years with a below average ice extent, and the year-to-year variation has decreased. The lowest sea ice extent in April between 1979 and 2021 was found in 2004, followed by levels observed in 2018 and 2021  (second and the third lowest extent, respectively).

In September, the ice extent varies considerably from year to year throughout the period. The lowest minimum extent since 1979 in September was detected in 2021, followed by levels in 2004 and 2017, practically the same values, sharing the second lowest extent.

Based on a least-squares linear regression, the rates of decadal decrease in April and September were -6.5% and -10.5%, respectively.

Causal factors

Higher sea and air temperatures result in less sea ice. A declining trend in the ice cover over large parts of the Arctic has been seen ever since satellite measurements began in 1979. As the ice extent in the Fram Strait is also strongly affected by processes in the Arctic Ocean, the ice extent in the Barents Sea is a more robust indicator for climate development. Ocean currents, such as the influence of Atlantic water reaching the Barents Sea, and precipitation also influence the sea ice.

Consequences

Sea ice plays an important role for the radiation balance on the Earth. Snow-covered sea ice can reflect almost 80% of the incoming solar energy, whereas open water absorbs 90%. Warming of the Arctic can thus lead to melting of the sea ice, which in turn results in more energy being taken up and the Arctic becoming still warmer.

In addition, some ecosystems and species are entirely dependent upon the sea ice. Some marine organisms live only in ice-covered waters, and whales, seals and polar bears are dependent upon the sea ice in their life cycles.

About the monitoring

It is important to monitor the sea-ice extent because it is vital for the climate in the Arctic and globally, and because it sets important limits for the ecosystems in the Arctic. Since monitoring by satellite monitoring started in 1979, a declining trend for the sea-ice extent in the Arctic is observed. Monitoring is important because conditions for sea ice are a key indicator for measuring the rate of climate change, and positive feedback mechanisms are also connected to the extent of sea ice. A reduction in sea ice changes the Earth’s radiation balance and can alter or displace the arctic ecosystems.