In the Alps, glacier cover was shrinking by 35 % from 1850 to the 1970s and
another 22 % by 2000 (Paul et al. 2004) and also in the Caucasus a severe mass loss
is evident since the little ice age (Zemp et al. 2008). In Central Europe, front
variations of glaciers are observed at 764 glaciers with an average time length of
65 years. But to determine the direct reaction of a glacier to climate change, ice
volume changes – the so called glacier mass balance – have to be observed. In the
mid latitudes, the mass balance of a glacier is mainly dependent on winter precipitation (accumulation) and summer temperature (ablation) which are measured
separately in spring and autumn. In Central Europe, these measurements are
available for 43 glaciers with an average number of observations of 20 years
(Zemp et al. 2008). One of the longest time series of mass balance is measured at
the Vernagtferner (46
52
0 N/10
49
0 E) in Tyrol, Austria (Fig. 3.5).
Direct measurements of both, winter and summer mass balance were initiated in
1964 (Reinwarth and Escher-Vetter 1999). Winter, summer and annual mass
balance since then are presented Fig. 3.5. The annual mass balance trend is negative
with some positive years in the 1980s and beginning 1990s and a prominent
negative peak in 2003 where a heat wave in Europe heavily accelerated the icemelt.
While the winter mass balance shows just a slight decreasing over the full period,
ice losses in summer are increasing considerably in the same time.
The trend of negative mass balances is therefore mainly caused by enhanced
melt in summer while changes in winter accumulation have only small influence.
The time series of area changes at Vernagtferner is even longer and documents a
glacier shrinking from 11.6 km
2 in 1889 to 7.9 km
2 in 2010.
Fig. 3.5 Winter, summer and annual mass balance of the Vernagtferner in Austria for the period
1964/65 to 2009/10
40
J. Stagl et al.
another 22 % by 2000 (Paul et al. 2004) and also in the Caucasus a severe mass loss
is evident since the little ice age (Zemp et al. 2008). In Central Europe, front
variations of glaciers are observed at 764 glaciers with an average time length of
65 years. But to determine the direct reaction of a glacier to climate change, ice
volume changes – the so called glacier mass balance – have to be observed. In the
mid latitudes, the mass balance of a glacier is mainly dependent on winter precipitation (accumulation) and summer temperature (ablation) which are measured
separately in spring and autumn. In Central Europe, these measurements are
available for 43 glaciers with an average number of observations of 20 years
(Zemp et al. 2008). One of the longest time series of mass balance is measured at
the Vernagtferner (46
52
0 N/10
49
0 E) in Tyrol, Austria (Fig. 3.5).
Direct measurements of both, winter and summer mass balance were initiated in
1964 (Reinwarth and Escher-Vetter 1999). Winter, summer and annual mass
balance since then are presented Fig. 3.5. The annual mass balance trend is negative
with some positive years in the 1980s and beginning 1990s and a prominent
negative peak in 2003 where a heat wave in Europe heavily accelerated the icemelt.
While the winter mass balance shows just a slight decreasing over the full period,
ice losses in summer are increasing considerably in the same time.
The trend of negative mass balances is therefore mainly caused by enhanced
melt in summer while changes in winter accumulation have only small influence.
The time series of area changes at Vernagtferner is even longer and documents a
glacier shrinking from 11.6 km
2 in 1889 to 7.9 km
2 in 2010.
Fig. 3.5 Winter, summer and annual mass balance of the Vernagtferner in Austria for the period
1964/65 to 2009/10
40
J. Stagl et al.