Climate Change is Changing Glacier National Park

Glacier National Park (GNP) in western Montana is on the verge of losing its namesake features to climate change. Given this fact, I made a point to visit the park this summer to see what remains of its famous glaciers before they completely melt away.

According to the National Park Service, the area that is now GNP was home to 150 glaciers at the end of the Little Ice Age in 1850. Today, because of rising global temperatures, only 25 remain and most are mere vestiges of what they once were. Looking ahead, if the current rate of melting continues, all of the park’s glaciers are expected to disappear by 2030, if not sooner.

Glaciers are dynamic entities that respond to changes in temperature and precipitation. They advance when more snow accumulates in the winter than melts in the summer. When this process is reversed, they retreat. Sadly, the new norm in GNP includes warmer summers and a decreasing snowpack.

The USGS, which monitors the park’s glaciers, reports that the mean annual temperature in GNP has increased 1.33°C (2.4°F) since 1900. That is nearly twice the global average. The park also now sees 16 fewer days each year with below-freezing temperatures. These warmer conditions mean that more precipitation is falling as rain rather than snow.

Beyond aesthetic changes to the landscape, the shrinking glaciers and reduced snow pack mean less melt water for the region and therefore warmer and drier summers. This, in turn, affects soil moisture and the proliferation of wildfires. It also has serious ramifications on the availability of fresh water for drinking and irrigation.

In arid regions, like the American West, people depend on mountain run-off from melting glaciers and winter snow packs for the majority of their fresh water. In western Montana, according to the NPS, snowmelt accounts for 60-80% of the annual freshwater supply. As temperatures rise and the stores of this precious resource dwindle, competition for it is expected to increase.

But, glaciers are not the only things changing in GNP. As the atmosphere heats up and the ice retreats, the park’s various ecosystems are also being reshaped. Sub-alpine trees are moving upslope replacing alpine meadows, for example. This changing distribution of vegetation affects the type of wildlife the park can support. While some animals can adapt and move upslope with their habitat, others, like the pika – a small furry relative of the rabbit who lives at high elevations and cannot survive temperatures above 75°F – already live at the end of their range and have no place to go.

The NPS has no plans to change the name of Glacier National Park.

"Repeat Photography", a USGS project, documents the changes to GNP's glaciers over the years. Credit: USGS/NPS

Images of Sperry Glacier from “Repeat Photography”, a USGS project, that documents the changes to GNP’s glaciers over the years. Credit: USGS/NPS