The Alsek Glacier retreat in Alaska unveils a newly formed island.
Each year, the glaciers recede a little further, releasing water flows that accumulate in increasingly large lakes. Recently, a geographical surprise has been revealed: the birth of a new island.
A mountain trapped in ice
Throughout much of the 20th century, a small mountain called Prow Knob was surrounded by ice, named for its resemblance to the bow of a ship. The ice acted as a wall, keeping the landmass connected to the continent. Aerial photographs from 1960 showed…
By the mid-century, part of Prow Knob had become the shore of Lake Alsek, although the glacier still maintained contact. That connection weakened until, finally, the summer of 2025 marked the definitive separation.
The island that emerged from the thaw
In just a few weeks, between July and August, an island emerged from the thaw. Since 1984, the arms of the Alsek Glacier have retreated more than five kilometers, feeding a lake that has grown from 45 to 75 km².
With less ice support, the edges of the glacier are now more prone to calving, which could further accelerate its retreat.
An unstoppable trend
Together with the neighboring lakes Harlequin and Grand Plateau, the region has seen the extension of its proglacial waters double in four decades. Studies indicate that the trend will continue, exposing new bodies of water —and perhaps more islands— in the coming years.
What may seem like a picturesque geographical accident is actually the visible footprint of a warming planet.
