Historic Glacier Changes in the American West
A.G. Fountain, H. Basagic, K. Jackson, M. Hoffman
Supported by NSF, NASA, USGS, NPS
South Cascade Glacier, WA
1960 USGS
2004 John Scurlock
Cummulative Mass Change (m weq)
South Cascade Glacier
Summer
Mass Balance
+
Winter
-
0
-4
-8
-12
-16
-20
-24
1955
US Geological Survey
1965
1975
1985
1995
2005
Trends in Winter Snowpack
(Mote et al., 2005)
80%
60%
40%
20%
Hypothesis: These trends in
snowpacks imply similar glacier
Changes.
Tasks
1. where are the glaciers?
2. how are they changing?
3. why are they changing?
8303 glaciers
Glaciers in the American West
1 : 24,000
3079
1158
450
463
42.5
688 km2
68.6
208
2.6
1475
73.3
1
0.09
1778
46.2
141
4.8
US Forest Service lands
National Park Service lands
Glaciers
3000
Area Distribution
Number
2500
2000
1500
1000
500
0
2.5
3
3.5
4
4.5
5
5.5
6
LogArea
Area(m)
(m2)
6.5
7
7.5
South Cascade Glacier, 1960
1958
Medicine Bow Range, CO
Hoffman
250 m
Clark Peak, Medicine Bow Range, CO.
- An
Hoffman
1999
Annual Precipitation (mm
Colder Dry Climates
8000
All Glaciers
7000
Wyoming
Warmer Wet Climates
California - Sierra Nevada
Cascades
Cascades
Cascades
Oregion
Idaho
Montana - Beartooth
6000
Colorado
5000
Montana - other
Oregon - Wallowa
4000
3000
2000
1000
0
-5
0
5
10
Annual Mean Temperature (C)
15 -5
0
10
Annual Mean Temperature (C)
Historic
Maps
Colder Dry
Climates
5
Gridded
Climate Data
PRISM
15
Beartooth, MT
Wind River, WY
Lewis
Range, MT
CO
North
Cascades
Sierra
Nevada
1998
Grinnell Glacier, MT
1938
Data Sources
For
Glacier Change
1907
T.J. Hileman
D. Fagre
August 14, 1907
G.K.Gilbert
2003
August 2, 2003
1960 USGS
South Cascade Glacier, WA
2004 John Scurlock
Darwin Glacier, CA
Hassan
Basagic
Satellite Imagery
ASTER
Mt Hood
DOQ
BrokenTop subscene 1967
RESULTS
1960s – current
~1900 - current
US Forest Service lands
National Park Service lands
Glaciers
1925
1950
1975
2000
1900
100%
2
80%
Fractional Area
2
Area (km )
1900
2.5
1.5
1
0.5
0.7
1950
1975
2000
Glacier Area Changes
60%
40%
20%
0%
0
1925
Coe
Eliot
Ladd
Cascades, OR
Collier
Newton Clark
White River
(Keith Jackson)
100%
Fractional Area
Area (km2)
0.6
0.5
0.4
0.3
0.2
75%
50%
Lyell West
East Lyell
25%
0.1
Sierra Nevada, CA
Lilliput
1925
1950
1975
1900
2000
100%
3.0
75%
Fractional Area
Area (km2)
Goddard
0%
4.0
2.0
1.0
0.0
1900
Darwin
Picket
0.0
1900
Conness
1950
1975
2000
1925
1950
1975
2000
50%
25%
0%
1925
(Hassan Basagic)
1900
Vulture Glacier
Swiftcurrent Glacier
Sperry Glacier
Lewis Range, MT
Grinnell Glacier
Sperry Group
1925
(Thanks to Dan Fagre)
1950
1975
2000
10
1.0
8
0.8
Fractional Area
Area (km2)
Total Glacier Area Changes
6
4
0.6
0.4
2
0.2
0
0.0
1900
1925
1950
1975
2000
1900
`
Oregon Cascades
Sierra Nevada
Lewis Range
1925
1950
1975
2000
Mt. Rainier, Driedger, ~1980
South Cascade Glacier, Fountain, 1984
Local Effects
Lyell, east lobe, Basagic, 2006
Colorado Front Range, Byerly, USGS, before1923
Equilibrium Line Altitude (ELA)
SnowAccumulation (z) = Ablation (z)
(direct, wind, avalanche)
= Heat balance
= RN + Hs + HL
Locally
deformed
ELA
Land
Surface
Growth Shrinkage
5000
Elevation Range
1913-1971
Elevation (m)
4000
3000
2000
1000
Error 1σ
0
-0.10 0.00 0.10 0.20 0.30 0.40 0.50 0.60 0.70 0.80 0.90
Thomas Nylen
Fractional Area Change
Keystone-Mast Collection
5000
1971-2002
Elevation (m)
4000
3000
2000
1000
0
-0.10 0.00 0.10 0.20 0.30 0.40 0.50 0.60 0.70 0.80 0.90
Fractional Area Change
1909
1916
1937
1962
Andrews Glacier
2001
Tyndall Glacier
1916
140
Photo: Herbert T. Cowling
Collection: RMNP Archives
120
1937
100
Photo: Larry Mayo
Collection: National Snow &
Ice Data Center
3
Area (m x 10 )
Andrews Gl.
2
80
60
Tyndall Gl.
1962
Photo: C.O. Harris
Collection: RMNP Archives
40
20
0
1885 1895 1905 1915 1925 1935 1945 1955 1965 1975 1985 1995 2005
Year
Matt Hoffman
2000
Photo: John Achuff
Collection: --
1925
1950
1975
2000
1900
100%
2
80%
Fractional Area
2
Area (km )
1900
2.5
1.5
1
0.5
0.7
1950
1975
2000
Glacier Area Changes
60%
40%
20%
0%
0
1925
Coe
Eliot
Ladd
Cascades, OR
Collier
Newton Clark
White River
(Keith Jackson)
100%
Fractional Area
Area (km2)
0.6
0.5
0.4
0.3
0.2
75%
50%
Lyell West
East Lyell
25%
0.1
Sierra Nevada, CA
Lilliput
1925
1950
1975
1900
2000
100%
3.0
75%
Fractional Area
Area (km2)
Goddard
0%
4.0
2.0
1.0
0.0
1900
Darwin
Picket
0.0
1900
Conness
1950
1975
2000
1925
1950
1975
2000
50%
25%
0%
1925
(Hassan Basagic)
1900
Vulture Glacier
Swiftcurrent Glacier
Sperry Glacier
Lewis Range, MT
Grinnell Glacier
Sperry Group
1925
(Thanks to Dan Fagre)
1950
1975
2000
60%
40%
20%
Fraction of Glacier Area Lost since 1900
66%
31%
24%
30%
40%
60%
360
10
320
8
280
6
240
4
200
2
160
0
120
-2
80
-4
40
-6
Temperature (C)
12
-8
1920
1940
1960
1980
2000
Year
12
10
160
8
6
120
4
2
80
0
-2
40
Temperature (C)
Precip (cm)
400
0
1900
200
Precip (cm)
-4
-6
0
1900
200
-8
1920
1940
Summer temp
1960
1980
2000
Year
12
10
8
160
120
6
4
Winter precip
2
0
80
40
-2
Winter temp
-4
-6
0
1900
-8
1920
1940
1960
Year
1980
2000
Temperature (C)
5-year running mean
Precip (cm)
PRISM
reconstructed
data
Conclusions
Glacier change in the West does not
conform to the expectation based on
trends in winter snow pack.
Climatic variations within regions
need to be examined carefully to
deduce glacier response.
The role of local topography warping
the equilibrium surface is crucial
and is important for understanding
the varying response of glaciers to
climate change.
This understanding is important for
interpreting past climate records
derived from glaciers throughout
the west.
Lyell, east lobe, Basagic, 2006