In northwest Montana, there's a place where the mountains fold so sharply into each other that it seems as if they were pressed together from above. Glacier National Park is located in this very spot, and for generations, its territory was covered in ice. Hundreds of glaciers stretched across its ridges, coloring every photograph blue-white and imprinting the rocks. Now this image is a document of what is actively disappearing, frame by frame, decade by decade.
What makes this story so astonishing is its speed. Not the geological speed of a global warming, but the speed of a single human lifetime. People alive today first visited a park covered in ice, and upon returning, they found exposed rock where glaciers had once pressed. This is precisely what the visual timeline of Glacier National Park shows us—not gradual change, but transformation in rapid motion.
The park at the time of its founding – 1910
The park at its founding in 1910 (Image courtesy of Pixabay)
An estimated 150 glaciers existed here in 1850, and most of them remained until 1910, when the park was established. The park owes its name largely to its location. Native Americans called the Glacier National Park area "the place of much ice," while other tribes described the park as "the land of shining mountains" because of the bright, reflective snow and ice visible from the plains to the east.
Although the glaciers that formed the park's majestic peaks were part of an ice age that ended about 12,000 years ago, today's glaciers are considered geologically recent, having formed about 7,000 years ago. These glaciers expanded significantly during the Little Ice Age, which began around 1400 AD, and reached their maximum size at the end of that period, around 1850. In other words, in 1910, the park was still located near this peak—a vast frozen archive pressed into the Rocky Mountains.
The first explorations were to map out what was there.
Early Surveying - Mapping What Was (by Carl Gilbert Grove, Public Domain)
After the establishment of Glacier National Park in 1910, the USGS began sending William C. Alden on annual expeditions to the park to survey and map its glaciers and topography. In 1914, the USGS published Alden's report, "Glaciers of Glacier National Park." These early studies provided scientists with a fixed starting point to which they returned again and again as the glaciers receded.
USGS scientists have been studying these glaciers since the late 1800s, building a vast research base documenting the extensive changes in glaciers over the past century. Ongoing USGS research combines long-term data with modern methods to deepen our understanding of the physical processes occurring within glaciers, their impacts on alpine ecosystems, and climate relationships. Paper maps and glass plate photographs taken during these early expeditions are now among the most valuable scientific documents housed in the park.
Grinnell Glacier - The Face of Loss
Grinnell Glacier – The Face of Loss (Image courtesy of Unsplash)
Grinnell Glacier, one of the most photographed glaciers in Glacier National Park, has retreated to the largely shaded upper reaches of its basin. The USGS resurvey project began shooting from the same vantage points and locations, and the visual results are striking. As the glacier retreated, Upper Grinnell Lake formed, and the change in elevation of Grinnell Glacier along the escarpment indicates a decrease in its volume over this period.
Studies of local topographic effects show that variations in glacier geometry, ice thickness, elevation, shading, avalanche input, and wind-blown snow likely explain the unique rate of change for each glacier. Grinnell Glacier is particularly well-documented precisely because it is located at an elevation accessible for hiking—visitors have been photographing it since the early 1900s, creating a continuous photographic record that cannot be reproduced by modeling.
The numbers speak for themselves – from 1966 to the present
The numbers speak for themselves – from 1966 to the present (Image courtesy of Pexels)
In 1966, there were 35 named glaciers in the park. By 2005, seven of them had shrunk to less than 0.1 square kilometers, leaving 27. By 2015, there were 26 named ice masses large enough to be considered glaciers. This half-century-long comparison is one of the most cited in all of American conservation science.
On average, glacier area in the park has decreased by approximately 39 percent since 1966. While the average loss was 39 percent, some glaciers have lost up to 85 percent of their area in the past 50 years. All glaciers in Glacier National Park have decreased in area, although the rate of retreat is uneven. While the differences are significant, the overall trend remains consistent.
Glacier decay – research results for 2023–2024.
Glacier decay – research results for 2023–2024 (Image courtesy of Unsplash)
A U.S. Geological Survey study conducted in late 2023 found that 11 glaciers in Glacier National Park had broken up due to the park's ongoing warming as a result of climate change. For years, it had been expected that the glaciers that give the park its name would melt, reducing their area to a fraction of its original size. Now, a study by Andrew Fontaine, Bryce Glenn, and Christopher McNeil has confirmed that glaciers continue to disappear across the West.
To conduct the study, the team used high-resolution aerial photographs taken between 2016 and 2020, as well as other imagery. Several glaciers have broken up and are considered critically endangered. Furthermore, the Boulder, Fishsure, and Grey Wolf glaciers have been reclassified as perennial snowfields. This reclassification is more significant than it initially appears—a snowfield is not a glacier and does not function as such from an ecological perspective.
Temperature as a driver of change
Temperature as a Driver of Change (bobfamiliar, Flickr, CC BY 2.0)
An analysis of meteorological data from western Montana shows rising summer temperatures and a decline in winter snowpack, which forms and supports glaciers. Since 1900, the average annual temperature in the park and surrounding region has increased by 1.33 degrees Celsius, 1.8 times the global average. This multiplier effect is significant—the park is not only warming with the planet, it is warming faster than most of the rest of the world.
The rate of warming has accelerated sharply since 1980, and the park has warmed by about 0.8 degrees Fahrenheit per decade since then. Although Montana's precipitation has remained unchanged, warmer winters are bringing more glacier-eroding rain than glacier-forming snow. This shift from snow to rain during the winter months is one of the more subtle, yet most damaging, changes in the system.
What did meltwater support?
What did meltwater support? (Image courtesy of Pixabay)
Glaciers play a vital role in the park's ecosystems, especially during the summer months. They provide a source of cold, clean water, as runoff cools stream temperatures during the driest and hottest periods of summer after the seasonal snowpack disappears. Without this cold buffer, stream temperatures rise, stressing species adapted to subzero water.
The U.S. Fish and Wildlife Service has listed the western glacier stonefly and the meltwater stonefly as threatened species, both listed as endangered. These insects inhabit only cold streams fed directly by glacial meltwater. The park is considered a habitat for a wide variety of plant and animal species and is home to some of the last remaining populations of endangered species, such as brown bears and bull trout, as well as ecologically important species such as bighorn sheep and black bears.
Fire comes into play
Fire appears in the picture (Image courtesy of Pexels)
Ice and fire have become a dual theme in Glacier National Park. In the Northern Rockies, earlier snowmelt has contributed to increased fire frequency and intensity, adding approximately 76 additional days to the fire season. In 2003, Glacier National Park experienced its worst fire season on record, burning 13 percent of the park's million acres.
In the northern Rockies, large wildfires are now occurring ten times more frequently than in 1970, and they cover approximately 45 times the area they once did. During the time period captured by these repeat images, it's clear that Swiftcurrent Glacier has retreated, while a wildfire has destroyed a patch of trees at the base of Swiftcurrent Mountain. This single image tells two stories: the retreat of cold and the advance of fire.
Visiting and closing period
Visit and closing window (Image courtesy of Pexels)
In 2024, more than 3.2 million visitors passed through one of Glacier's entrances, nearly 300,000 more than in 2023. This was only the fourth year in which visitor numbers exceeded 3 million, approaching the 2017 record of 3.3 million. Many of these visitors come specifically to see what may be lost for future generations.
The increase in recreational visitors occurred outside the traditional peak season: Glacier National Park recorded record numbers in May, September, and October. These figures convey a certain urgency. March 2025 was designated World Glacier Day as part of the UN's International Year of Glacier Conservation, reflecting the rapid and accelerating loss of glaciers. In 2023 and 2024, for the first time, all 58 glaciers included in the Global Reference List had negative mass balance. The park's glaciers are part of a global, not just regional, rethink.
Future Prospects – What Do Monitoring and Research Say?
Future Outlook – What Monitoring and Research Say (Image courtesy of Unsplash)
The USGS Benchmark Glacier Project conducts glaciological research and collects field data on individual North American glaciers, including Sperry Glacier in the park. This data provides direct evidence of glacier change, and the extent of future ice loss depends on the trajectory of greenhouse gas emissions. It is this last point that leaves the picture truly unresolved.
In 2024, Glacier National Park received over $1.9 million in Inflation Relief Act funding to continue bison reintroduction efforts, inventory cultural resources impacted by climate change, and protect and restore whitebark pine. The U.S. Geological Survey (USGS) describes the continued retreat and loss of ice mass from smaller glaciers in the park as inevitable—the rate of this process remains unclear. Meanwhile, researchers estimate that some glacial ice in Glacier National Park will disappear between 2030 and 2080 if current climate conditions continue unabated.
Conclusion: Living Archive
Conclusion: Living Archive (europeanspaceagency, Flickr, CC BY-SA 2.0)
The visual chronology of Glacier National Park is also a testament to scientific patience. USGS photographers, who returned to the same mountain ranges year after year, using the same coordinates as the 1911 photographers, created something rare: a continuous visual record of a landscape in motion.
Comparing photographs from the mid-19th century with modern images, we find abundant evidence that the park's glaciers have retreated significantly since 1850. This data tells us more than just about ice. It also reveals information about water, wildlife, fires, temperatures, and the relationship between the place that gave it its name and the characteristics that gave it its name.
The park won't disappear. Its mountains, lakes, and wildlife remain extraordinary. But every summer that passes without restoration adds another frame to this timeline—another image of exposed rock where ice once pressed. The archive continues to grow, whether we look at it or not.
The article "The Changing Landscapes of Montana's Glacier National Park: A Visual Timeline" first appeared in The Garden Magazine.