Melting Glaciers

Grinnell Glacier 1910 and 2017
A mountainous glacier. A small mountainous glacier.
Morton J. Elrod, K. Ross Toole Archives, 1910
Lisa McKeon, USGS, 2017

In 1966, the park had 35 named glaciers large enough to be considered active. By 2015, only 26 named glaciers remained. The average area reduction was 39 percent, though some lost as much as 85 percent. This trend of glacier retreat is expected to continue as temperatures rise.

Why are the park’s glaciers shrinking? Glaciers shrink when summer melting outpaces winter snow. Despite occasional big winters or frigid months, the glaciers are melting as long term average temperatures increase. Ice core records from polar regions show that Earth’s average temperature and the amount of carbon dioxide in the atmosphere change in tandem. In the past century, human activities have emitted a significant amount of carbon dioxide, which is causing the Earth to heat up—and glaciers to melt.
Learn more from the U.S. Geological Survey. 

When will all the park’s glaciers be gone? A geospatial model, published in 2003, predicted that two of the park’s largest glaciers would become inactive by 2030 if carbon dioxide levels continued to rise. For several years, those glaciers actually melted faster than the rate predicted by the model, prompting researchers to refine analysis of glacier retreat with more physical detail. These recent studies have revealed the real world complexity of mountain landscape change. Though the park’s glaciers are all getting smaller, variations in snow avalanches, ice flow dynamics, and ice thickness cause some glaciers to shrink faster than others. Sometimes a glacier will retreat very quickly where it was thinly and widely spread, only to shrink much more slowly when only the shaded, high elevation ice remains. Some small remnant ice may persist late into the 21st century or even beyond, depending on how and when we act.  

A man stands on a cliff with a camera.
Morton J. Elrod photographing Chaney Glacier in 1911.

Visualizing the Change

The United States Geological Survey (USGS) started the Repeat Photography Project in 1997 with a systematic search of Glacier's archives for historic photographs of glaciers in the park. They found many images to work with from early photographers such as Morton Elrod, T.J. Hileman, Ted Marble, F.E. Matthes, and others who scoured the park to publicize its beauty and earn their livings. The USGS scientists then hiked the historic images into the field to rephotograph them from the exact same vantage point.

Historically and today, photographing the glaciers can only occur in a narrow window in late August and early September after the previous winter's snow has melted from the ice and before the first snows of autumn. It is only in the late summer season that the glaciers can be clearly seen.
Jackson Glacier 1911 and 2009
A mountainous glacier. A small mountainous glacier.
Morton J. Elrod, K. Ross Toole Archives, 1911
Lisa McKeon, USGS, 2009
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?

Blackfoot and Jackson Glacier 1914 and 2009
A mountainous glacier. A small mountainous glacier.
E. C. Stebinger, GNP Archives, 1914
Lisa McKeon, USGS, 2009
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? 

Boulder Glacier 1932 and 1988
A glacier with people standing on and around it. An empty gravel mountainous landscape.
George Grant, GNP Archives, 1932
Jerry DeSanto, K. Ross Toole Archives, 1988
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. 

Sperry Glacier 1930 and 2008
A mountainous glacier. An empty gravel mountainous landscape.
Morton J. Elrod, K. Ross Toole Archives, 1930
Lisa McKeon, USGS, 2008
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 1911 and 2005
A mountainous glacier. A mountain with some snow and ice. A red line outlines where a glacier used to be.
Campbell, USGS, 1911
Blase Reardon, USGS, 2005
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.

Thunderbird Glacier 1907 and 2007
A mountainous glacier. A small mountainous glacier.
Morton J. Elrod, GNP Archives, 1907
Dan Fagre, USGS, 2007
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. 

Grinnell Glacier 1926 and 2008
A glacier with people standing on and around it. A small mountainous glacier.
Morton J. Elrod, K. Ross Toole Archives, 1926
Lisa McKeon, USGS, 2008
What makes a good photo to re-photograph? The large boulder in front of Grinnell Glacier was used by Morton J. Elrod and other scientists as a baseline to measure the retreat of the glacier. The boulder is now referred to as “Elrod’s Rock” and the glacier has retreated a half mile from this point. Grinnell Glacier was and still is one of the most photographed glaciers in the park. In the early 1900s, park visitors were able to hike or horseback ride eight miles up the Many Glacier Valley to see this glacier. Today, this is a strenuous, but still popular hike once the snow has melted from the trail in late summer.

Grinnell Glacier 1911 and 2008
A mountainous glacier. A mountain landscape with some snow and ice.
T. W. Stanton, USGS, 1911
Lisa McKeon, USGS, 2008
George Bird Grinnell described this wall of ice as being 1,000 feet high in 1887. As of 2008, the wall of ice was gone and Grinnell Glacier is no longer visible in the contemporary photograph. Salamander Glacier, now separate, lies along the wall below the ridgeline. Perched on the upper left wall is the small, rounded Gem Glacier. Although its area has remained stable, the glacier is losing volume.

Do all glaciers melt at the same rate? No, variations in snow avalanches, ice flow dynamics, and ice thickness cause some glaciers to shrink faster than others, but one thing is consistent: all the glaciers have receded since 1966. The trend of retreat, apparent here at Glacier National Park, is also seen around the world.

Grinnell Glacier 1938 and 2016
A person stands on top of a glacier in a lake with mountains in the background. A mountain lake with snow and ice on a mountain in the background.
T. J. Hileman, GNP Archives, 1938
Dan Fagre, USGS, 2016
The person standing on top of Grinnell Glacier in the 1938 photograph taken by T.J. Hileman gives the viewer a sense of the huge scale. Repeating the historic image today, and including the person for scale, would require a boat. 

People stand in front of a glacier below a mountain.

How to See a Glacier

With a little effort you can see a glacier with your own eyes here. Some are visible from the road and others require a day hike.

People walk around a bright lake with a glacier and mountains in the background.

Glacial Geology

Once you know what to look for, viewing Glacier's landscape can seem like reading a textbook on the geologic effects of glaciation.

People stand on a beach and look at a wildfire.

Climate Change

Global warming is melting the park’s glaciers, increasing the severity and likelihood of wildfires, and shifting wildlife habitat.

People load onto a shuttle bus.

Reduce Your Carbon Footprint

Many people fall in love with Glacier and then want to reduce their footprint.

A green plant sprouts from ashes.


Learn about what Glacier National Park is doing to reduce carbon emissions.

Last updated: July 3, 2019

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West Glacier, MT 59936


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