Autumn Arrives in the Southern Hemisphere

As autumn settled in during late March 2025, significant changes unfolded across the Southern Hemisphere, particularly in Antarctica. The onset of cooler air and water temperatures heralded a crucial phase: the regrowth of sea ice around the southernmost continent.

NASA's Eye in the Sky

Utilizing the MODIS (Moderate Resolution Imaging Spectroradiometer) aboard NASA's Terra satellite, scientists observed the early formation of new sea ice in the Amundsen Sea, particularly noteworthy due to its proximity to the influential Pine Island and Thwaites glaciers. This newly-formed ice, identified as 'grease ice,' presents a distinctive gray hue.

A Critical Observation

This fresh sea ice follows a recent record low in its annual extent across Antarctica, boasting the second-lowest reach in satellite history. Interestingly, the Amundsen Sea Embayment experienced an extraordinary persistence of some sea ice this year, contrasting starkly with the overall decline stretching through the austral summer.

The Mystery of Persistent Ice

Scientists remain puzzled as to why certain areas of sea ice held on longer than expected. Several theories exist, including warm water infiltrating the bay from under the glaciers and residual ice from the previous winter jamming the space, impeding the movement of ice.

A Tale of Contrast

Against the backdrop of newly formed ice, stark patches of open water emerge, particularly in front of the Pine Island Glacier. These dark regions are likely heat-affected zones where warm waters below the glacier's tongue interact with offshore winds to prevent any ice formation.

Looking Ahead: A Winter of Ice Growth

In the days following the satellite's capture of these images, the sea ice expanded even further, poised to continue its thickening and spreading during the frigid, dark winter months. This sea ice is vital for supporting local ecosystems, providing habitats for wildlife, and mitigating wave action that threatens glaciers and ice shelves.