Mendenhall Glacier: A Retreating Record

The Mendenhall Glacier, thirteen miles from downtown Juneau, has retreated approximately two miles since nineteen fifty. The lake that has formed in the space the glacier formerly occupied did not exist when the photographs from the nineteen fifties were taken. The lake is there because the ice is not.

Alaska holds more glacial ice than the entire contiguous forty-eight states combined, roughly seventy-five thousand glaciers covering approximately twenty-nine thousand square miles. It is losing that ice faster than anywhere else in North America. The rate of loss is not uniform and not linear: it is accelerating.

The Mendenhall is one of the more accessible examples of this process. There is a visitor center with a window facing the glacier, and the glacier is visibly different from the photographs on its walls. The photographs were taken within living memory. The difference between them and the present view is a two-mile recession, a lake, and the exposure of bedrock that has not seen daylight in several thousand years.

Glaciologists use the term retreat to describe what is happening, which is accurate but passive. The glacier is not retreating. It is melting. The distinction matters because retreat implies the glacier might come back. Under current projections, the Mendenhall will lose a significant fraction of its remaining volume within the lifetime of people alive today.

The Juneau Icefield, which feeds the Mendenhall and dozens of other glaciers in the region, is one of the largest icefields in North America. What happens to it will determine what this valley looks like when the children visiting the visitor center today bring their own children here.