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the majority of mountain regions of the world (Kadota et al., 1997; Liu et al., 2002; Paul et al., 2004;
Aizen et al., 2006b; Surazakov et al., 2007) in response to a rapid increase of air temperature and
changes in precipitation partition (rain instead of snow) at high mountains.
Permafrost and periglacial zone
Extensive distribution of permafrost, water thermal erosion and snow chemical weathering are
characteristic elements of periglacial high elevated mountain areas, implying two main processes:
frost action – wedging, heaving, trusting, and cracking, that all serve to prepare bedrock or soil for
erosion, while mass movements transport the loosened debris. The combination of such factors
results in geomorphic features that are unique to high elevated periglacial areas, i.e. hillslope
erosion and modified landforms. The dominated role of permafrost in periglacial landform is
apparent. In some high elevated mountainous areas the volume of stored ground ice is comparable
to that of modern glaciers, accounting for up to 20% of the total runoff (Gorbunov et al., 1997;
Vilesov and Belova, 1989). The increase in air temperature also has an effect on the alpine
permafrost. An increase in permafrost temperatures from 0.3°C at the early 1970s up to 0.6°C in
the 2000s has enlarged the thickness of the permafrost active-layer by 23%. The modeling estimates
show that the lower boundary of permafrost distribution has shifted by about 150–200 m upward
during the twentieth century (Marchenko et al., 2006). The seasonal soil thaw has increased by
30-35% during the last 30 years (Gorbunov, 2007, Gorbunov et al., 1997, Severskiy E., 2007).
However, the stratums of seasonal permafrost reaction to climate changes remain ambiguous in
different high elevated landscape conditions and require long-term monitoring.
Rock glaciers also play a role in high elevated periglacial geomorphology and hydrology. The
available evidence suggests that, while rare, in the South American Andes, TP, Himalayas and
central Asian, mountains rock glaciers are numerous and probably contain significant amounts of
buried ice that contribute to periglacial processes and meltwater runoff formation. Flowing water in
periglacial high elevated mountain areas exerts an important influence on glacier behavior and
geomorphological processes, producing both benefits and hazards to human settlements in the low
river reaches. The hydrology of some periglacial areas is characterized by the periodic or occasional
release of large amounts of water in catastrophic outburst floods, creating devastating mudflows
and flooding down through river valleys. The periglacial processes of high elevated mountainous
areas have been studied very little and require special attention.
2.4.6 Atmospheric aerosol at high elevations
The high elevation areas, located far from direct anthropogenic emissions, are ideal sites for the
monitoring of atmospheric background conditions and for the early detection of global change
processes. Moreover in these areas the presence of atmospheric aerosols and greenhouse gases
affects the regional climate by altering the radiation budgets that are part of the Earth’s energy
balance (IPCC, 2007, Forster, 2007). As pointed out also by United Nations Environment
Programme, the environmental impact of aerosol and other anthropic pollutant emissions has
significantly increased in the last fifty years mainly due to the growth of energy demand related to
industrial processes and vehicular traffic. This strongly influences the Earth’s climate and water
cycle from local to global scales, both in urban and remote areas, like mountain regions. In fact, the
aerosol can directly affect cloud properties: for example, an increase in aerosol concentration will
increase the number of droplets in warm clouds, decreasing their average size, reducing the rate of
precipitation, and extending the cloud lifetime (Spichtinger and Cziczo, 2008). In addition, as also
pointed out during the Atmospheric Brown Cloud (ABC) project (Ramanathan et al., 2008), the
aerosol can directly absorb or reflect the incoming solar radiation before it reaches the Earth’s
surface. In this way the temperature fields (both horizontal and vertical) and the hydrological cycles
can be perturbed. In South Asia, it has been found that the presence of huge layers of absorbing
aerosols (e.g. black carbon, BC) may intensify the Indian monsoon through the so-called
‘‘Elevated-Heat-Pump’’ (Lau et al., 2006; 2008), and favour the early monsoon onset with increased
rainfall coming to northern India during May (Lau and Kim, 2006). However, as reported in
Bollassina et al. (2008) and confirming similar findings proposed by Ramanathan et al. (2005),
Meehl et al. (2008) found that over India BC aerosols can lead to an increase in premonsoon rainfall,
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