Glacier National Park guide · 2 min read
Glaciers and Climate Change
The jagged peaks of Glacier National Park owe their shape to ice. During the last ice age, enormous glaciers ground through these mountains, and most of that ice has vanished over roughly the past 12,000 years.
Their work remains in U-shaped valleys, bowl-shaped cirques, knife-edged ridges called arêtes, and long lakes that stretch outward from the foot of the tallest summits.
The climate has warmed and cooled several times since then. The most recent cold spell, the Little Ice Age, lasted from about 1550 to 1850. The park's glaciers grew and pushed forward during those centuries, though they never came close to their ice age size. They have been retreating since that period ended. By the middle of the twentieth century, comparisons of older maps and photographs gave clear evidence of change among the 150 glaciers once known in the park.
Today the park is a site of landmark scientific research on global climate change. Its shrinking glaciers offer a clear view of how a warming climate is reshaping ecosystems here and around the world. Scientists expect more of the park's precipitation to arrive as rain instead of snow, so the alpine snowpack will keep declining. With less snow building up each winter, the remaining glaciers will keep melting away.
Geography makes the picture more complex. The park straddles the Continental Divide, where warm, wet Pacific air from the west collides with cold, dry Arctic air from the northeast. The western side is milder and wetter, while the higher eastern side sees stronger winds, more sun, and long cold snaps. With more than 7,000 feet of difference between the lowest and highest ground, temperatures generally fall as you climb, creating many microclimates. Snow can fall in any month, and the deep accumulation known as the Big Drift has buried Going-to-the-Sun Road.
