Few people ever see the alpine glaciers in Southwest Alaska's Ahklun Mountains. If current melting trends continue, no one will see them.
The obscure glaciers, hanging on the upper reaches of the mountains in the northeast corner of remote Togiak National Wildlife Refuge, are melting at a rate that would make them disappear entirely by the end of this century, according to a new study.
Analysis of mapping and aerial photos dating back to the 1950s shows that they have shrunk by nearly half in the past five decades, said the study by researchers from the U.S. Fish and Wildlife Service and Northern Arizona University. Ten of the 109 Ahklun Mountains glaciers mapped by the U.S. Geological Survey in the 1970s have already disappeared, and the rest are on pace to do so in the coming decades, according to the study, available online in the Journal of Fish and Wildlife Management.
Unlike the large and famous blue-white glaciers of Southeast Alaska and Prince William Sound, the meager Ahklun glaciers get little attention.
"These are kind of small, out-of-the way glaciers, and that's what makes them wonderful for this kind of study," said Pat Walsh, the supervisory biologist at the Togiak National Wildlife Refuge and lead author of the study.
Visitors who come to the refuge are generally focused on activities like fishing, boating and wildlife viewing, not ice-hunting, and there is no easy way to get to the glaciers without aircraft. Even many locals seem to be unaware of them, said Walsh, who has been working at the Togiak refuge for 14 years and studying the glaciers for about half that time.
"If I were to ask people in Dillingham, I know some people aren't aware of the existence of these glaciers," he said.
The Ahklun glaciers are nestled in concave cirques and other high-altitude sites. They are somewhat similar to the ice remnants of the small and imperiled high-altitude glaciers found in the U.S. Rocky Mountain region. In Montana, for example, Glacier National Park is expected to lose all of its glaciers by 2030 -- perhaps a decade earlier than that.
But several thousand years ago, the Ahklun glaciers were more like the big sheets and rivers of ice found elsewhere in Alaska. About 20,000 years ago, they were part of an ice sheet that extended about 6,000 square miles, Walsh said.
The current melt-out is not the first time the Ahklun glaciers have pulled a disappearing act. About 9,000 years ago, after the last Ice Age ended, the glaciers retreated to the mountains' highest elevations, according to previous studies. Over the next 6,000 years, even those remnants may have melted out, according to the new study.
Then the glaciers reformed and built up to their recent maximum at the end of the mid-19th century, Walsh said. That glacial growth coincided with a period is known as the "Little Ice Age," a cooling period that lasted a few hundred years.
While the Ahklun glaciers never grew back to anything close to the size of the ice cap that existed 20,000 years ago, they were much bigger in the 19th century than they are now, extending about a kilometer (0.6 miles) beyond today's termini, Walsh said.
Eventually, even the big Alaska glaciers that currently draw thousands of cruise-ship passengers will follow the Ahklun glaciers' lead, he said.
"This is a look into the future," he said.