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| Titel |
Changes in area and volume of all Swiss glaciers over the last 25 years |
| VerfasserIn |
Mauro Fischer, Matthias Huss, Martin Hoelzle |
| Konferenz |
EGU General Assembly 2014
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 16 (2014) |
| Datensatznummer |
250086353
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| Publikation (Nr.) |
 EGU/EGU2014-200.pdf |
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| Zusammenfassung |
| Since the mid-1980s, glaciers in the European Alps have shown widespread and accelerating
mass losses. These glacier changes have been investigated in several studies both focusing on
area and length changes as well as on volume losses. Because the Alps are dominated by
relatively small glaciers, we argue that a sound analysis of glacier elevation changes can
only satisfactorily be done if source data of sufficient quality is available. For the
Swiss Alps, these prerequisites are now given with the new Swiss Glacier Inventory
INVGLAZ10MF derived by manual digitization from high-resolution (50cm) aerial
orthophotographs and a new digital elevation model swissALTI3D of the same acquisition
dates.
By comparing the DHM25 level1 Digital Elevation Models (DEMs) acquired during the
1980s with the swissALTI3D DEMs from 2008-2011 and combining the former with the
1973 inventory and the latter with the 2010 inventory, we present glacier-specific changes in
area, surface elevation, volume and geodetic mass balance for every single glacier in
Switzerland. Because there are – depending on the individual acquisition dates of the
source data – significant differences in the observation period over which glacier
elevation changes have been derived by DEM differencing, we present an approach to
temporally homogenize resulting changes. This is necessary for directly comparing
individual glaciers or glacierized catchments. Furthermore, we validate our results using
volume changes calculated over the same periods from photogrammetrically derived
DEMs.
According to the latest Swiss Glacier Inventory, the total area still glacierized in
Switzerland by 2010 amounts to 944 km2 (-28% or 366 km2 since 1973). Very small glaciers
(< 0.5 km2) account for 82% of the total number, but in relative terms even more glacierized
area (and volume) belongs to fewer glacier entities compared to 1973. Observed area changes
are largest between 2800-2900 m a.s.l. and still significant even above 3500 m
a.s.l.
The resulting geodetic mass balance data reveals that the area-weighted mean of 1420 still
existing glaciers amounts to -0.73 m w.e. a-1 for our reference period 1986/87-2009/10. For
some main hydrological catchments the mean mass balances range from -0.60 m w.e. a-1 for
more maritime areas on the north-facing slopes of the Alps to -1.17 m w.e. a-1 for more
continental and inner-Alpine valleys in the southeast of Switzerland. Our comprehensive
dataset shows that there is no significant correlation between average glacier surface area and
geodetic mass balance. However, the surface slope of the glacier tongue (lowermost 10%),
median glacier elevation and mean aspect can – to some extent – explain the observed mass
changes. The overall volume loss calculated over the analyzed period is -22.1 km3. |
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