Impacts and Risks of Global Change - Impact of Global Changes on Mountains: Responses and Adaptation - page 61

Due to much of the cryosphere being at a temperature close to 0°C,
mountain regions are highly sensitive indicators of climate change. This
is manifested by 7000 km² of mountain glaciers having disappeared in the
last four decades of the 20th century. The European glacier extent decreased
30-40% during the 20th century (Haeberli and Beniston 1998, Lamprecht
and Kuhn 2007) and further 30-50% of glacier mass may be lost by 2100
(Maisch et al. 1999). These changes in the cryosphere will have signifi cant
repercussions in the hydrological cycle and alter availability of water and
seasonality of run-off regimes (Ellenrieder et al. 2007). After a period of
increased discharge due to melting, the compensatory discharge of melt
water will wane as glaciers disappear. Coupled with changing seasonality
of precipitation, with less rainfall in summer and more liquid precipitation
in winter this may lead to severe water shortage due to exhausted water
stores. The cryosphere and linked hydrological cycle in mountain regions
is most severely affected by the impacts of a warmer climate and feedbacks
are transferred to other resource areas, i.e., hydro power.
The extreme summer of 2003 in Europe (see Schär et al. 2004) may give a
glimpse of potential future consequences of regional warming to mountain
water cycles. Due to the extreme dry conditions melt water runoff from
Alpine glaciers could hardly compensate the water defi cit in the foreland
river systems, e.g., the upper Danube, where it caused lowest recorded
water levels since more than a century with multiple economic losses due
to very limited river trade or reduced production of electricity at water
power plants along the Danube and its tributaries (EEA 2009).
As at the end of this century (2071-2100), about every second summer
could be as warm (or even warmer) and as dry (or even drier) as the summer
of 2003 (Schär et al. 2004), periods of minimum discharge like in 2003 are
expected to become more frequent (see, e.g., Mauser et al. 2008). Due to
the fact that glacial and snow melt waters will no longer compensate the
missing precipitation, it is very likely that the consequences will be more
serious than in 2003.
Besides this specifi c reaction to global climate change impacts, it is the
unique spatial situation of mountain areas' natural, i.e., meteorological,
hydrological, vegetation, geomorphological conditions that change
dramatically over relatively short distances. Consequently boundaries
between these systems experience drastic shifts due to climate warming
or changing precipitation. These extraordinary spatial variations of
environmental resources mean a tremendous challenge to societies in
mountain areas. Due to the limited utilizable space there are rather restricted
alternatives to the specialized economic situation.
Although there is a common pattern of Global Climate Change
challenges to mountain areas worldwide (e.g., melting of the cryosphere,
increase of natural hazards), it has to be stated that due to the position in