Glacier Repeat Photos

In 1910, Morton Elrod documented how Grinnell Glacier’s mass filled the basin and how the glacier was then joined with the ice apron we now call the Salamander (right). Close inspection of Gem Glacier (top-center) reveals a loss of thickness and volume over the years as well. 

Although melting glaciers are the most visible indicators of climate change in the mountains, the entire mountain ecosystem is responding. Using both repeat photography and tree-ring studies, scientists have documented that trees are growing faster, becoming taller and filling in the spaces in between trees. Young seedlings have established and are surviving in areas where deep snowpack and harsh weather conditions had previously excluded them. How do you think this vegetation change will impact wildlife?

Jackson Glacier was once part of Blackfoot Glacier, one of the largest glaciers in the park. By 1939 the expanse of Blackfoot Glacier had receded and separated into two distinct basins, giving rise to the separate names of Jackson and Blackfoot glaciers. Along with the glacial recession evident from this pair, can you pick out another big change? 

This is one of the earliest photographs repeated from the park that shows the disappearance of glacial ice. It helped to start the current Repeat Photography Project. The 1932 photograph shows a guide, wearing chaps, and three clients next to the ice cave. This was one of the popular multiday routes during the heyday of horseback trips through the park and underscores the charisma that glaciers had for early park visitors. Boulder is now too small to be considered active. 

Repeating Elrod’s 1930 photograph from the exact spot was impossible since it was shot from the elevated surface of the now receded glacier. The terminus of the glacier has retreated beyond the field of view, but these images give a sense of the glacier’s extent and mass early in the twentieth century. Sperry Glacier is a benchmark glacier for USGS scientists. Scientists use its measurements of annual change as a baseline to compare with other glaciers and to predict future changes.

Shepard Glacier is now less than 25 acres in size and is therefore no longer considered an active glacier. As the park's glaciers melt, the effects will be felt far downstream. Glaciers store about 70% of the world’s freshwater. They regulate stream temperatures and maintain stream flow during late summer and drought periods when other sources are depleted. Without glacial meltwater, summer water temperatures will increase and may stress temperature sensitive species, such as aquatic insects and native trout.

Acquiring the 2007 photograph of Thunderbird involved some serious scrambling on cliffs and made USGS scientists admire Morton J. Elrod, the original photographer, who carried much heavier and bulkier gear over the same terrain. Using arial imagery, scientists know that Thunderbird melted from 33 acres in 1966 to 26 in 2015, a loss of 21%, putting it very close to the inactive cutoff of 25 acres.