Adaptation to Climate Change in Mountain Regions: Global Significance of Marginal Places - Impact of Global Changes on Mountains: Responses and Adaptation - page 143

Exacerbating the effect of the vertical change gradient is the circumstance
that total available space becomes less along this gradient. If one moves
upwards in mountains, less and less area is available for ecosystems and
societies that depend on them. In all mountains the drive upwards on
the slopes ultimately ends with a summit. This means that not only do
temperature-dependent systems need to be able to rapidly move upwards
they are also running out of space. For example the snow leopard habitat
in the Himalaya has found to be affected by climate change induced shifts
of the tree-line. As a result of the upwards shift a recent study (Forrest et
al. 2012) has shown that the snow leopard habitat might shrink by 30%.
The principal repercussions of the vertical distribution of ecosystems in
mountain regions, i.e., volatility to change and diminishing available space
as one moves upwards, provide the physical basis for an understanding of
the effect of climate change and the way its impacts precipitate in mountain
regions and the societies they host.
Impact of climate change on the natural environment
It is expected that with continued climate change increases in mean
annual air temperature are considerably higher in mountain regions than
elsewhere. Given that the benchmark for dangerous global warming of
2°C increase of global average air temperature seems increasingly likely
to be exceeded (e.g., Allison et al. 2009) this is alarming for all mountain
dwellers. For example temperatures on the Tibetan Plateau are expected to
rise substantially more (Rupa et al. 2006), which would have catastrophic
effects for the Greater Himalayan people and ecosystems (Xu et al. 2009,
Anderson and Bowe 2008, Hansen et al. 2008, Solomon et al. 2009). Indeed
it can already empirically be shown that in some mountain areas warming
trends and anomalies are elevation dependent (Giorgi et al. 1997, Matulla
et al. 2004), and temperatures increase more rapidly in higher altitudes
(e.g., in the Alps). That means that on top of the more fragile situation of
vertically organized ecosystems as described above, the changes in one
of the principal impacts of climate change, i.e., temperature, are more
pronounced in mountain regions. Extremes in impact and vulnerability,
in driver and in capacity to respond, combine.
Mountain regions are highly sensitive indicators of climate change. This
is manifested by 7,000 km² of mountain glaciers that have disappeared in
the last four decades of the 20th century (Nogués-Bravo et al. 2007). 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 (Haeberli 1999, Maisch et al. 1999, Zemp et al.
2006). These changes in the cryosphere will have signifi cant repercussions
in the hydrological cycle and alter availability of water and seasonality