Glaciers around the world are in retreat, but not Alaska’s Hubbard Glacier. It’s steadily advancing into Disenchantment Bay, threatening to block the entrance to Russell Fjord and disrupt life in the nearby town of Yakutat.

Top image: Hubbard Glacier, July 22, 2014.

Scientists have been tracking the growth of Hubbard Glacier since 1895, and since that time it has made contact with Gilbert Point, once in 1986 and again in 2002. But in both instances, the natural dam was breached by the mounting water pressure, returning the fjord to normal levels.

Hubbard Glacier, July 13, 2002.

NASA’s Earth Observatory explains why this glacier is so unique:

According to Leigh Stearns, a glaciologist at the University of Kansas, Hubbard’s advance is due to its large accumulation area; the glacier’s catchment basin extends far into the Saint Elias Mountains. Snow that falls in the basin either melts or flows down to the terminus, causing Hubbard to steadily grow. In addition, Hubbard is building up a large moraine, shoveling sediment, rock, and other debris from Earth’s surface onto the glacier’s leading edge. The moraine at the front gives the glacier stability and allows it to advance more easily because the ice does not need to be as thick to stay grounded. (If it is thin, it can start floating and will not necessarily advance.)

New research by Stearns suggests the fjord could permanently close sometime between 2025 and 2043 — a development that could have profound consequences for the nearby town of Yakutat, whose residents are dependent on the fjord’s marine life.

Google Maps.

Hubbard Glacier, July 13, 2002.

More at NASA’s Earth Observatory.

Image credits: NASA Earth Observatory images by Joshua Stevens, using Landsat data from the U.S. Geological Survey and Hubbard Glacier data provided by Marcy Davis of The University of Texas at Austin.