A century of glacier change in the American West
Photos from the USGS, NPS
Andrew G. Fountain
Portland State University
Acknowledgements: NSF, NASA, USGS, and to Matt Hoffman, Hassan Basagic, Thomas Nylen, Mark DeVisser, and
David Percy
Fountain, AGU 2007
Geologic Hazards
debris flows
Oregon Highway 35, Nov 7, 2006
Doug Jones
John Scurlock
Fountain, AGU 2007
Glaciers in the American West
1 : 24,000
3079
1158
450
463
42.5
68.6
8303 glaciers
208
2.6
688 km2
1475
(266 miles2)
73.3
1
0.09
1778
46.2
141
4.8
US Forest Service lands
National Park Service lands
Fountain, AGU 2007
Glaciers
Climate
Local
Meteorology
Surface Mass
And
Energy Exchange
South Cascade Glacier
monitored since 1958
Net Mass Change
Dynamic
Response
Effect on
Landscape
Fountain, AGU 2007, after Meier 1965
Runoff
Changes
In
Geometry
Hundreds of glaciers
Meier,
1965
some
photographed
since 1900
1907
Darwin Glacier
Sierra Nevada
Kings Canyon Nat. Park
August 14, 1907
G.K.Gilbert
2003
August 2, 2003
Hassan Basagic
Fountain, AGU 2007
Grinnell Glacier
Lewis Range, Montana
Glacier National Park
1938
T. Hileman
1981
C. Key
1998
D. Fagre
2006
K. Holzer
Courtesy Glacier National Park, US Geological Survey
Fountain, AGU 2007
Gannett Glacier, WY
Meier, 1951
Fountain, AGU 2007
Fraction of Glacier Area Lost since 1900
25%
46%
31%
66%
24%
30%
42%
40%
52%
US Forest Service lands
National Park Service lands
Fountain, AGU 2007
Glaciers
Trends in Winter
Snowpack since 1950
(Mote et al., 2005)
Mote et al., 2005
Fountain, AGU 2007
1913-1971
5000
Mount Rainier
Elevation (m)
4000
3000
2000
1000
0
-10% 0%
10% 20% 30% 40% 50% 60% 70% 80% 90%
Area Change
1971-2002
5000
Elevation (m)
4000
3000
2000
1000
0
-10% 0%
10% 20% 30% 40% 50% 60% 70% 80% 90%
Area Change
Nylen, 2004
Fountain, AGU 2007
1913-1971
5000
1900 - 1970
Elevation (m)
4000
3000
2000
1000
0
-10% 0%
10% 20% 30% 40% 50% 60% 70% 80% 90%
Area Change
5000
1971-2002
1971-2002
1970 - 2006
Elevation (m)
4000
3000
2000
1000
0
-10% 0%
10% 20% 30% 40% 50% 60% 70% 80% 90%
Area Change
Fountain, AGU 2007
Mount Rainier
4392m
4
Temp (C)
2
0 1084m
-2
2157m
-4
-6
3782m
-8
-10
1890
Fountain, AGU 2007
1900
1910
1920
1930
1940
1950
1960
1970
1980
1990
2000
2010
>3000m
2500-3000m
Red = decreasing trend
Blue = increasing trend
Fountain, AGU 2007
1949 - 2003
1949 - 2003
What’s happening in the Sierra Nevada?
1.
Steep (~30o) small glaciers avalanche snow.
2.
Increasing spring temperatures lengthen
ablation season
Temperature (C)
Temperature (C)
1900
1920
1940
1960
1980
2000
Andrews Glacier
4
Front
Range, Colorado
3 Spring
2
1
0
-1
-2
-3
12
11
0.2
y = 0.017x - 33.8
A
Summer
10
9
8.8
8
7
y = 0.004x + 1.5
6
Temperature (C)
-2
Lyell, east lobe, Basagic, 2006
-3
Winter
-4
-5
-5.4
-6
-7
-8
1900
y = 0.004x - 13.7
1920
1940
1960
1980
Fountain,2000
AGU
2007
Climatically Sensitive and Insensitive Glaciers
1960 USGS
8 SEP 2004
Basagic
Snow accumulati on = S + S '
Ablation = f [R + R ' , T + T ' , H + H ' , W + W ']
where R is the direct ' unabstruct ed ' value
R ' is the topographi cally induced
perturbati on
Fountain, AGU 2007
Glaciers < 3000m
affected by winter and
summer temperatures
25%
46%
31%
66%
24%
30%
42%
40%
56%
Glaciers > 3000m
affected by spring
and summer
temperatures
Fountain, AGU 2007
US Forest Service lands
National Park Service lands
Glaciers
Fountain et al, 2007
Conclusions
Glacier behavior is consistent with
broad climatic trends, however
identifying regional factors requires a
local understanding of the climate and
glacier setting.
The role of local topography is
Important to understanding the
spatially varying response of
glaciers to climate change.
In general, regions of thermally
susceptible snowpacks (near the
melting point) suffer from both increases in winter and summer
temperature increases. Whereas the
small but high elevation glaciers appear
to be responding to spring/summer
temperatures.
Reid Glacier, Nt. Hood
2007 John Scurlock
Fountain, AGU 2007
South Cascade Glacier, WA
1960 USGS
Fountain, AGU 2007
2004 John Scurlock