Repeat Photos of Jackson Glacier, 1914–2024: Shrinking, but Not on Schedule

Glacier National Park has always been a place of change, which makes it a special place to watch and study the power of climate change — natural and otherwise. Repeat photographs, taken from the same spot years apart, show it plainly.

Jackson Glacier and Mount Jackson in 1914, photographed by William Alden of the U.S. Geological Survey. A version of this picture appeared on the cover of Alden's 1914 USGS report.

The same view in 2020. NPS.

Side by side, the two show how dramatically Jackson Glacier has shrunk since the park's early years.

Alden's report, Glaciers of Glacier National Park, 1914.

In that report Alden wrote: "Glacier National Park derives its name and much of its interest from the presence of many small glaciers. Very much of the grandeur of its wonderful Alpine scenery, the final sculpturing of the great mountain valleys and of the amphitheaters at their heads, and the production of the basins of its many beautiful lakes are due to the action of the more extended glaciers of the past."

The predictions

Watching the glaciers shrink, many scientists predicted they would disappear.

• 2003: Researchers Myrna Hall and Daniel Fagre published a paper in BioScience on two of the park's glaciers, Blackfoot and Jackson. Hall had written a computer model (GLACPRED) that projected advance or retreat decade by decade from 1990 to 2100, from melting rates in historical measurements.
• The model predicted that, if melting continued at the same rate, the two glaciers would be gone by 2030 — and it was thought that most of the park's smaller glaciers would likely be gone by then too.
• But it was an early model: it didn't account for glacier volume and other physical factors that affect melting, and it covered only those two glaciers, not every glacier in the park.
• 2009: A new look found Blackfoot and Jackson seemed to be melting faster than predicted, and the date was informally moved up to 2020.
• The dates spread widely online and appeared on exhibits around the park. As 2020 neared and it was clear the glaciers would still be there, the predictions were taken down.

What actually happened

Jackson and Blackfoot glaciers did not disappear by 2020. In fact, they retreated relatively little between 2009 and 2020.

Taking a repeat photo of Jackson Glacier from the moraine, September 3, 2009. USGS.

The same spot on August 29, 2020. NPS.

Satellites agree with the photos. Outlines traced from satellite images show the glacier's footprint did shrink, but only a little: about 5% of its area melted away between 2005 and 2015.

Jackson Glacier's outline in 2005 (red) and 2015 (blue); the red edges are the area lost. NPS.

Photos from Going-to-the-Sun Road in 2021 and 2024 show no noticeable change in the glacier's main body.

Jackson Glacier from a distance, August 31, 2021. Image from the National Park Service's page.

The same view, September 4, 2024. Image from the National Park Service's page.

Why glaciers shrink at different speeds

All of the park's glaciers are getting smaller — but not at the same rate. Differences in snow avalanches, ice flow and ice thickness make some shrink faster than others. A glacier can retreat very quickly where its ice is thin and spread wide, then shrink much more slowly once only the shaded, high-elevation ice remains.

Jackson Glacier in 1911, 2009 and 2020. Image from the National Park Service's page.

The first two photos above show the glacier pulling back hundreds of feet between the earliest picture and 2009; the last shows little change between 2009 and 2020 — good news for anyone who likes seeing ice on the mountains.

Still shrinking

Blackfoot and Jackson have slowed down, but they are still shrinking, and the latest measurements show that every glacier in the park is getting smaller. Between 1966 and 2015, every named glacier lost area — some more than 80%.

• A 2019 study counted 82 glaciers in the park of at least 0.1 km² (Martin-Mikle and Fagre, 2019).
• In 2015, Miche Wabun, Whitecrow and Thunderbird glaciers each covered 26 acres. The named glaciers are only part of the park's permanent snow and ice.

Jackson Glacier from its lateral moraine, September 3, 2009. USGS.

The same view, August 29, 2020. NPS.

Every sign points to the park's glaciers continuing to shrink, just not all at once. Depending on how much the climate warms, Glacier National Park may remain a place to watch glaciers melt for years to come.

Taking a repeat photograph. Image from the National Park Service's page.

Sources

Based on "Repeat Photos of Jackson Glacier," part of the series Photographing Change in Glacier National Park, National Park Service; a work of the United States government in the public domain. The NPS article cites Alden, Glaciers of Glacier National Park (USGS, 1914); Hall and Fagre, "Modeled Climate-Induced Glacier Change in Glacier National Park, 1850–2100" (BioScience, 2003); Martin-Mikle and Fagre (2019); Fagre, McKeon and Fountain's glacier margin time series (USGS ScienceBase, 2017); and Christopher White, The Melting World (2013).