Sea Ice
Monitoring sea ice changes in polar regions
Sea Ice Bulletin
Analysis of sea ice extent, volume and concentration in the Arctic and Antarctic regions. Using the Operational Mercator global ocean analysis system this seasonal bulletin provides insights about the regional and global sea ice annual cycle.
Latest Bulletins
When seawater freezes, a layer of ice forms on the surface of the ocean. The polar Arctic and Antarctic regions hold the largest amount of sea ice on the planet. Following a seasonal cycle, sea ice in these regions grows to its maximum extent in the winter and melts away in the summer.
Sea ice annual cycle in the Arctic Ocean and in the Southern Ocean (2000).
Why it matters?
Sea ice plays an important role in ocean circulation and in regulating the Earth’s climate. The planet’s Albedo, or the ability to reflect sunlight, is heavily influenced by the amount of sea ice. Ice’s white colour, has high reflectivity, which helps the Earth bouncing a substantial portion of incoming solar radiation back into space.
©XavierBoymond
Arctic
The Arctic region is warming more than 2x faster than the global ocean.
As a result, the sea ice in the Arctic is melting rapidly. Since 1979, the Arctic region lost an average of 4% of sea ice per decade.
During the Summer months, the drop in sea ice is specially significant, with an average of sea ice loss of 12,6% per decade.
Arctic Sea ice extent between 1993 and 2025.
Increasing warming in the region is leading to a drastic reduction in sea ice volume.¹
Sea ice volume informs on the total amount of sea ice – both thickness and area – providing information on the amount of ice that survives from year-to-year.
According to the Intergovernmental Panel on Climate Change (IPCC), at a high emissions scenario, it is expected that the Arctic will become sea ice free (an area of sea ice below 1 million km²) during the summer months before 2050.
Antarctic
Antarctic sea ice extent between 1993 and 2025.
In 2023, Antarctic sea ice reached the lowest extent ever recorded.
Sea ice cover in the Antarctic ocean region has presented high variability from year-to-year, without a clear trend since 1979. However, in 2016 the region seems to have entered a new state of low sea ice.
In 2023, sea ice levels in the Southern Ocean reached record-lows since the beginning of satellite records. Although there is still not a significant trend in sea ice extent and volume in the region, the last few years have registered continuously low sea ice values.
How is sea ice measured?
Due to its remoteness, extreme temperatures and ice-full passages, polar regions are difficult to access; hindering the collection of in-situ (direct) measurements in these areas of the globe, which are scarce. Due to the development of satellites, sea ice has been continuously observed since1979.
Ocean numerical models, mathematical representations of the ocean, provide information about sea ice variables and dynamics between the air and sea (sea ice concentration, thickness and sea ice temperature).
Sea Ice
Sea Ice Extent
It’s the area covered by a significant amount of sea ice. Scientists define a threshold of at least 15% sea ice concentration (km²).
Sea ice Concentration
Percentage (%) of sea ice cover within the data grid cell
Sea Ice Volume
Derived from sea ice concentration and sea ice thickness information integrated over a respective area (km³).
