Glacier recession since the Little Ice Age: Implications for water storage in a Rocky Mountain landscape

Abstract

Glaciers have significant influence on hydrology, vegetation, and wildlife in mountainous regions, and are receding globally. To quantify the impacts of sustained glacier loss, we mapped a complete set of glacier areas from the Little Ice Age (LIA) using very high-resolution satellite imagery (30 cm) within Glacier National Park (GNP), Montana, a region that encompasses 4098.81 km2 in the northwestern United States. We measured glacier change across the park using LIA glacier area as a baseline and then estimated change in glacier area and volume over time. An estimated 146 glaciers existed within the current boundaries of GNP during the LIA. By 2005, only fifty-one (35 percent) persisted. Nearly 90 percent of LIA glaciers had lost more than 50 percent of their area by 2005. This decrease in glacier area equates to an estimated ice volume loss of 1.52 km3, or 1.37 km3 of water storage, roughly equivalent to 90 percent of Lake McDonald, the largest lake in the park. Understanding rates of deglaciation and implications for water storage and use can assist local resource managers and downstream communities in planning for change.

Keywords

• glacier
• moraine
• recession
• little ice age
• climate change
• imagery