NASA Images Show New Island Formed by Retreat of Alaska’s Alsek Glacier

NASA satellite imagery has recently unveiled a never-before-seen island in Alaska, formed from melting glacier ice. The island itself was newly created within Alsek Lake when, after a few decades of retreat, the once-connected-to-the-peninsula-end Alsek Glacier became detached from little old Prow Knob. Melting ice and rising water turned something that had once been a junction on the mainland into an island. The transformation is a sign of the large-scale changes that are underway in glacial regions.

Retreat of glaciers, and formation of new islands

As per Space.com report, since 1984, the Alsek Glacier has been retreating at a steady pace of over 3 miles. When the ice melted, water collected in pools; these eventually became Alsek Lake. The glacier once surrounding Prow Knob eventually retreated, leaving Prow Knob surrounded by water.

At the core of the find is a pair of pivotal images taken: one in 1984 snapped by Landsat 5 and another shot up in August 2025 using Landsat 9. These photographs make obvious the extent to which the ice has retreated and water has supplanted where much of this used to be. It is a record not just of retreat, but also of the remaking of the geography in this part of Alaska.

Effects on landscape and stability

As glaciers advance and retreat, so do the landscapes — inflating lakes, precarious ice fronts, new patches of earth. As the ice on land melts and is removed, the front end of a glacier becomes ever less stable, more disposed to large breakoffs (a process called calving).

Broader climate implications

“The appearance of this island is a visual representation that climate change isn't some future catastrophe. Southeast Alaska and the region are undergoing rapid change, fueled by glacier melt that is reshaping hydrology, ecology and geography.