Alarming Findings: Glaciers in the Western United States Are Disappearing

A recent study by Portland State University has uncovered the alarming disappearance and transformation of glaciers in the Western United States. The inventory, updating a mid-20th-century record, found that many glaciers have vanished or no longer qualify as glaciers. This loss poses serious environmental challenges, including affecting water flow and contributing to sea level rise.

Glaciers in the Western United States are disappearing. 

A recent study by researchers at Portland State University has revealed significant changes in glaciers. The findings include the complete disappearance of certain glaciers, the cessation of movement in others, and a reduction in size for some below the minimum threshold of 0.01 square kilometers. Additionally, the study identified certain formations as rock glaciers, which are essentially rocky debris containing ice within their pores.

Detailed Inventory by PSU Researchers

Andrew Fountain, a geology professor emeritus at PSU, and research assistant Bryce Glenn, inventoried glaciers and perennial snowfields in the western continental U.S. using aerial and satellite imagery between 2013 and 2020. The inventory, published in the journal Earth System Science Data, identified 1,331 glaciers and 1,176 perennial snowfields. 

It updates a mid-20th century inventory, derived from U.S. Geological Survey topographic maps made over a 40-year span, and provides a baseline for estimating future changes amid a warming climate.

“Glaciers are disappearing and this is a quantification of how many around us have disappeared and will probably continue to disappear,” Fountain said.

Excluded Glaciers and Environmental Impact

The new inventory excludes 52 of the 612 officially named glaciers because they are no longer glaciers. The official names are those listed in the federal Geographic Names Information System — the nation’s repository for the names and locations of landscape features. Milk Lake Glacier in Washington’s Mt. Baker-Snoqualmie National Forest and Wyoming’s Hooker Glacier have disappeared altogether; 25 were instead classified as perennial snowfields, which unlike glaciers don’t move; 18 had areas smaller than the commonly used threshold of 0.01 square kilometers or roughly the size of two football fields side-by-side; and seven were considered rock glaciers.

The loss of glaciers impacts more than aesthetics. Glaciers act as a natural regulator of streamflow, Fountain said. They melt a lot during hot dry periods and don’t melt much during cool rainy periods. As glaciers shrink, they have less ability to buffer seasonal runoff variations and watersheds become more susceptible to drought. Retreating glaciers also leave behind sharp, steep embankments on either side, which can collapse and result in catastrophic debris flows. Globally, the loss of glaciers is also a major contributor to sea level rise.

Fountain’s co-authors are Bryce Glenn, a PSU alum and research analyst, and Christopher McNeil, a geophysicist with the USGS’ Alaska Science Center. Looking ahead, the group is studying the volume change of the glaciers to see how much ice they’ve lost since the USGS mapping.

Missing Glaciers: List of officially named glaciers not classified as glaciers and excluded from the final inventory

Reference: “Inventory of glaciers and perennial snowfields of the conterminous USA” by Andrew G. Fountain, Bryce Glenn and Christopher Mcneil, 15 September 2023, Earth System Science Data.
DOI: 10.5194/essd-15-4077-2023