Climate Change

CO2 and Temperature correlation chart. A line graph showing to lines mirroring each other until one rises way above the other.
In the past century, human activities have emitted a significant amount of CO2, which is causing the Earth to heat up—and glaciers to melt—at an alarming rate.

Over the last 100 years, the planet’s surface has warmed by about 1.5°F. In recent years, Northwest Montana has warmed at about twice that rate. This rapid rate of warming is melting the park’s glaciers, increasing the severity and likelihood of wildfires, and shifting wildlife habitat.

Three people standing on a lake shore watching a huge wildfire at night.
As the climate warms, projected increases in wildfire frequency and area burned are expected to drive up costs associated with health effects, loss of homes and infrastructure, and fire suppression.

Warmer, drier, conditions increase wildland fire frequency and severity.

A combination of human-caused climate change, land use, and forest management all influence wildfires in complex ways. Over the last century, fire exclusion policies have resulted in higher fuel availability in most U.S. forests. Warmer and drier conditions have contributed to an increase in the incidence and severity of wildfires in the western United States since the early 1980s, a trend that is expected to continue as the climate warms and the fire season lengthens. The expansion of human activity into forests and other wildland areas has also increased over the past few decades. In addition to threatening individual safety and property, wildfire can worsen air quality locally and, in many cases, throughout the surrounding region. This can lead to substantial public health impacts including increased incidence of respiratory illness. Increased wildfire activity is also expected to reduce the opportunity for outdoor recreation activities, affecting quality of life as well as tourist economies.

Shepard Glacier 1911 and 2005
A mountainous glacier. A small mountainous glacier.
Campbell, USGS, 1911
Blase Reardon, USGS, 2005

Fewer and smaller glaciers means less and warmer water.

For generations, Glacier National Park’s ice has provided cold water to countless people and wildlife, but that is changing. The park had over 100 glaciers when it was established in 1910. In 2015, only a couple dozen met the size criteria to be considered active glaciers. Today, they are all melting.

Warmer and more variable winter and spring air temperatures have caused more precipitation to fall as rain rather than snow, and has led to earlier snowmelt in the spring. As this trend continues, reduced winter snowpack and glacial loss will greatly decrease the major sources of groundwater recharge and summer runoff, resulting in a lowering of water levels in streams, rivers, lakes, and wetlands during the growing season.


Fewer glaciers and warmer temperatures means less water for people and agriculture.

The effects of reduced snow and ice pack will be felt in areas far away from the park as well. It is estimated that nearly 50% of freshwater used by humans is from mountains. As temperatures increase, and droughts become more frequent, the demands for agricultural and municipal water use are likely to increase, further reducing available water resources.

Water flowing from dwindling glaciers in the park is used to irrigate wheat, canola, and soy crops in the United States and Canada. Glacier’s waters are also used to generate electricity for millions of people as it passes through dozens of hydroelectric dams in the Columbia River watershed.

A dead fish lies on the bottom of muddy pond.
Waters warmer than 70F can be lethal to Glacier's cold-adapted cutthroat trout. NPS PHOTO

Less cold water is bad for fish and aquatic insects.

Glacial ice keeps river and stream temperatures cold. During the summer, glacial and other perennial ice patches, feed high mountain streams as they melt. As these sources disappear, less cold water is available for the species that rely on it. As water temperature rises, the amount of habitat in streams for invertebrates and fish will be reduced. Additionally, less water in the system will lower groundwater tables, altering riparian vegetation communities. Without glacial melt water, summer water temperatures will rise and may cause the local extinction of temperature sensitive aquatic species. These alterations in temperature could lead to a disruption of the aquatic food chain, which may impact keystone aquatic species such as bull trout.

mountain scene with yellow line drawn through subalpine forest
This photo from the Logan Pass area illustrates upslope movement of treeline during the last 100 years. Trees left of the yellow line are only 80 years old, while those to the right are 500 to 600 years old.

Warmer temperatures mean shifts in where plants can grow.

Alpine areas are known to harbor a rich diversity of rare and endemic plants. Some rare plants are slow to migrate or disperse when compared to annual or invasive plants. Climate change has already altered tree distribution and ranges in Glacier. Over the last century, a warmer climate has shifted the treeline up in elevation with subalpine tree species encroaching into higher elevations.

Alpine plants are generally low-growing and long-living. Because of their remote locations, alpine plant communities have been relatively unaffected by humans in the past, but these changes in vegetative patterns are early warnings of potential harm to plant richness, diversity, and well-being.

A moose swims through water.
Warmer winters could increase parasites, like ticks, that prey on moose.

Warmer temperatures affect wildlife.

Climate change has direct impacts on the movement, migration, and habitats of wildlife. Species that are mobile with large geographic ranges, and are more generalists in their diet, are able to tolerate a wide range of climatic conditions, and will likely better adapt to a changing climate. Specialist species that are not able to tolerate a wide range of climatic conditions may decline as their habitat shifts and shrinks. A species such as the wolverine, which is dependent on persistent spring snow cover for denning, may have less habitat available as warmer temperatures reduce snowpack.

A shuttle bus and a shuttle schedule.


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

A shuttle bus drives toward the camera. Text says Logan Pass.

Reduce your Carbon Footprint

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

Historic image of a person photographing a glacier

Glacier Repeat Photography

All the glaciers in the park are melting. Click here to find out why.

Last updated: August 7, 2020

Contact the Park

Mailing Address:

PO Box 128
West Glacier, MT 59936


(406) 888-7800

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