Glacier Shrinkage and Effects on Alpine Hydrology
A.G. Fountain, H.J. Basagic, D.H. Clark
Supported by the US Geological Survey, NSF BCS-0351004; NASA NNGO4GJ41G
South Cascade Glacier, WA
1960 USGS
2004 John Scurlock
Glacier Effects
on
Basin Runoff
Variability
Runoff Delay
Timing of peak runoff
Peak Delay
Fountain and Tangborn, 1985
Limit of Downstream Effects
Matt Hoffman
L*
Number of Glaciers in the American West
~1712
National Park Service lands
192
1225
US Forest Service lands
Glaciers
23
191
34
52
1
Total Glacier Area
~553 km2
National Park Service lands
49.9
417
US Forest Service lands
Glaciers
18.5
54.1
2.1
11.5
0.1
Cummulative Number of Glaciers
Size Distribution of Glaciers
Rocky Mountain
National Park
10000
1000
100
10
1
0.1
1.0
10.0
100.0
Area (km2)
(km2)
1000
Frequency (number)
900
800
700
600
500
400
300
200
100
0
0.1 0.3 0.6 1.0 1.6 2.0 2.5 3.2 4.0 5.0 6.3 8.0 10 13 16
Area (km2)
(km2)
South Cascade Glacier, 1960
Glacier Shrinkage
Tyrolian data courtesy of F. Paul
Geography, University Zurich-Irchel
Grinnell Glacier
Glacier National Park, 1938 - 1998
1938
T.J. Hileman
1998
D. Fagre
Bahr and Meier
1000
3.0
2.5
2.0
100
1.5
1.0
10
0.5
0.1
1.0
10.0
0.0
100.0
1000
900
1.0
0.9
800
700
0.8
0.7
600
500
400
0.6
0.5
0.4
300
200
0.3
0.2
100
0
0.1
0.0
0.1 0.3 0.6 1.0 1.6 2.0 2.5 3.2 4.0 5.0 6.3 8.0 10 13 16
2
Area(km
(km2)
Area
)
Total Volume Loss (m weq)
2
Area (km
(km2)
Area
)
km3
3.5
Cummulative Volume Loss
4.0
1
Number
Total
Glacier Volume Loss
Cummulative Number of
Glaciers
10000
Colorado Front Range - John Achuff
Norrland Sweden
Approximate Values of Glacier Change
1960’s to current
National Park
North Cascades
Mount Rainier
Olympic
Yosemite-Sequoia
-Kings
Glacier
Rocky Mountain
Number of
Glaciers
321
100 (26)
165
Area
km2
117 ±1
93
34
Δ Area
km2
Δ Volume
km3
m
-8 ±1
-2
-2
-0.8 ±0.1
-0.18
-0.07
7
2
2
45
6
-2
-0.03
5
127
33
-3
-0.08
2
-0.3
-0.003
2
28
1.4
Wheeler Peak
Great Basin National Park
Matt Hoffman
Matt Hoffman
Matt Hoffman
Rock Glacier Distribution
National Park Service lands
US Forest Service lands
?
Glaciers
Regions with debriscovered Glaciers
?
?
Matt Hoffman
Rock Glaciers / Buried Ice
(population not well known,
effects not well known)
Clean glacier
Rock-covered glacier
L. Mattson
Mount Sopris, CO
Conclusions
1. Hydrologic influence (variability, delay of seasonal peak) imposed
by glaciers extend roughly 5 glacier “lengths” downstream. Effects
melt volume and water quality can extend much further.
2. The “small” glaciers (<1 km2) account for almost half of the glacier
area in the west and half of the melt water volume. They seem to
be changing the most, yet are the least studied and hardest to define.
3. Debris-covered glaciers appear to be very common and are largely
unrecognized sources of melt water. They may effectively double
the area of ice present in a given region.