New sea ice will appear in a major bay in West Antarctica in the fall of 2025, while old sea ice survives the Southern Hemisphere's summer melt season. As fall descends on Antarctica, sea ice begins its seasonal return,NASA has captured stunning images of new ice growth in the Amundsen Sea.
Scientists are concerned about the persistence of "grease ice" near Pine Island Glacier and Thwaites Glacier, both of which are known for contributing to rising sea levels. The unusual longevity of the region's ice hints at deeper, little-understood ocean processes, such as subsurface heat and ice jams, that are shaping Earth's southernmost waters. This ice will only grow from here, playing a key role in buffering glaciers and supporting marine ecosystems.
In late March 2025, autumn ushered in the Southern Hemisphere, and cool air and water temperatures brought significant changes to Antarctica. One of the most significant changes is the regeneration of sea ice around Antarctica. NASA's Terra satellite used its MODIS (Moderate Resolution Imaging Spectroradiometer) instrument to capture stunning views of new ice forming in the Amundsen Sea in West Antarctica.
This fresh sea ice is likely a type of thin, soft ice known as "grease ice," which appears gray in satellite images. Most of them formed near the fronts of Pine Island Glacier and Thwaites Glacier—two giant glaciers known for their large and accelerating contributions to global sea level rise. However, unlike glacial ice, sea ice is already floating when it forms and does not contribute to sea level rise.
Grease ice is the early stage of sea ice formation and consists of a thin, sticky layer of small ice crystals on the sea surface. It has a gray, oily appearance and is formed when ice floes (tiny needle-like crystals) accumulate and condense into clumps before solid ice sheets form in calm, cold climates.
The new ice comes just weeks after Antarctic sea ice reached its annual minimum, tying it for the second-smallest extent in satellite records. Despite widespread summer melting across much of the Antarctic continent, the ice in Amundsen Bay is unusually persistent. Some of this longer-lasting ice was called multi-year ice, and cracked white patches can still be seen drifting away from the coast.
While scientists are not yet sure why sea ice in the region has remained so strong this year, several factors may have played a role. For example, warm currents flowing from beneath the glacier tongue into the bay affect the amount of melt to varying degrees each year. Additionally, leftover ice from last winter could clog the bay, preventing winds and currents from blowing the ice away.
In stark contrast to the old and new sea ice, several areas of open water appear almost black, including the area directly in front of Pine Island Glacier. These areas are likely ice-free because the water welling up beneath the glacier's ice tongue is relatively warm, and offshore winds can blow away any ice that grows there.
The sea ice has expanded further in the days since this photo was taken, and will continue to thicken and expand during the dark, cold winter months. Sea ice plays an important role along Antarctica's edge, both by providing habitat for animals and by inhibiting wave erosion of the floating fronts of adjacent glaciers and ice shelves.
Compiled from /scitechdaily