Glaciers shrinking

by Cat Urbigkit

Greg Kerr of the University of Wyoming gave the Wyoming Water Development Commission and the Wyoming Legislature's Select Water Committee an alarming overview of the glacial melt problem occurring in the Wind River Mountains at a meeting last week in Pinedale.

Kerr explained that the Wind Rivers are home to 63 glaciers covering 17 square miles, including seven of the 10 largest glaciers in the Rocky Mountains.

Although no recent research on our receding glaciers has been conducted, Kerr explained that in the late 1980s, UW researchers looked at Gannett Glacier, which covers 1.4 square miles, and the Dinwoody Glacier, covering 1.2 square miles.

Kerr emphasized the importance of these two glaciers, pointing out that when the study was done, Gannett and Dinwoody received 30 percent of visitors to the Wind River Range, which amounted to about 23,000 visitors per year in 1989. The glaciers are popular for fishing, mountain climbing and backpacking, as well as acting as water storage reservoirs, contributing to downstream flow in late summer and fall.

Kerr said researchers used a variety of techniques to assess glacial melt, including repeat ground photography, aerial photo analysis, ice radar measurements and measuring glacial runoff.

Comparing photographs of the Dinwoody Glacier taken in 1935 and 1998, demonstrates glacial decline. A second set of photos, in 1988 and 1999, show continued decline. Another set of 1935 and 1988 photos show a large expanse of ice gone, including an entire ice sheet. Kerr said that the photographs show less decline at higher elevations, but a decline nonetheless.

Aerial photographs taken in 1958 and 1983 show differences in ice elevations as well as the surface area covered by the glaciers. Kerr said that researchers estimate the depth loss due to melt at 61 feet for the Gannett Glacier, and 77 feet at Dinwoody, since 1958. Kerr explained that the water equivalent loss was 48,000 acre-feet at Gannett and 52,000 acre feet at Dinwoody.

"This is two glaciers of 63," Kerr explained.

The loss at Dinwoody is about the same amount of water stored in Guernsey Reservoir, he said.

Researchers calculated that glacial extent declined 36 percent from 1950 to 1999, a period of 49 years, but the most loss, at 24.74 percent, was from 1989 to 1999

"That's a significant amount in 10 years," Kerr said.

Kerr explained that with the glaciers in decline, there would be changes in runoff, creating supply issues. He suggested that this is a factor water managers need to consider in future planning.

Kerr pondered the effect of the recent drought on the glaciers in the Wind Rivers, suggesting that it may have accelerated the ongoing decline. He also wondered if weather modification projects, such as cloud seeding, could help slow the decline by acting as an insulator.

Kerr reported that in 2002, U.S. Geologic Survey scientists sampled glacial ice cores in the Wind Rivers, and determined that the average air temperature in the high elevations may have increased by more than 6 degrees Fahrenheit in the last five years.

"These rates of warming are substantially higher than for the U.S. as a whole," Kerr said.

Kerr urged more research directed at understanding the Wind River's glaciers, adding, "we may have glaciers that are already gone."

Kerr is expected to present a research-funding request to WWDC and the legislature for consideration during the upcoming budget session.