Geologic Publications for Mount Rainier

Spatial and temporal variations of glaciers (1913-1994) on Mt. Rainier and the relation with climate

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Author(s): Thomas H. Nylen

Category: PUBLICATION
Document Type: M.S. Thesis
Publisher: Portland State University
Published Year: 2004
Volume:
Number:
Pages: 128
DOI Identifier:
ISBN Identifier:
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Abstract:
Databases have been constructed for the purpose of studying glacier changes at Mt. Rainier. Glacier cover on Mt. Rainier decreased 18.5% (112.3 km² to 88.1 km²) between 1913 and 1971 at a rate of about -0.36 km² a^-1. The total area in 1994 was 87.4 km², which equates to a rate of -0.03 km² a^-1 since 1971. Glaciers with southerly aspect lost significantly more area than those with a northerly aspect, 26.5% and 17.5% of the total area, respectively. Measured and estimated total volumes for Mt. Rainier glaciers also decreased. From 1913 to 1971 the total volume decreased 22.7% from 5.62 km³ to 4.34 km³ and from 1971 to 1994 decreased 3.1% to 4.21 km³. Nisqually Glacier shows three cycles of retreat and advance but an overall loss of 0.44 km² since 1931. Cross-correlation with snowfall suggests about a decade response time for the glaciers.

The pattern of terminus change through this century has been consistent between the glaciers. Between 1913 and the late 1950s, the major glaciers were retreating, with an average retreat of 1,318 m. Following this period and up to the early 1980s the glaciers advanced an average distance of 390 m. Since 1980, the terminus positions of all but three glaciers, Emmons, Winthrop and Cowlitz, retreated.

Though the response has been similar, spatial variations exit in the magnitude of response. Southern glaciers, which are on average smaller decreased in area, volume and length more than the northern glaciers. The northern glaciers decreased in area by 17.5%, while the southern glaciers decreased by 26.5%. As for the terminus positions, the southern glaciers retreated on average 1,957 m, which is approximately three times as far as the average for the northern glaciers. The spatial variations in area and volume of the glaciers are caused primarily by differences in incoming solar radiation, size and elevation range. With more solar radiation the southern glaciers have smaller mass balances and over time cause spatial differences in the size of the glaciers. Smaller glaciers appear to be more sensitive to climate changes than larger glaciers because they have smaller elevation ranges.

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In Text Citation:
Nylen (2004) or (Nylen, 2004)

References Citation:
Nylen, T.H., 2004, Spatial and temporal variations of glaciers (1913-1994) on Mt. Rainier and the relation with climate: M.S. Thesis, Portland State University, 128 p..