Global Change and Mountains: Consequences, Responses and Opportunities - Impact of Global Changes on Mountains: Responses and Adaptation - page 101

and magnitude of hazards and extreme events, such as, fl oods, windstorms,
droughts, cloud bursts and fl ash fl oods will increase with increasing
temperature and changes in precipitation pattern (Kohler and Maselli 2009,
IPCC 2007a,b). The global warming is to intensify the hydrological cycle
in mountain watersheds changing the frequency, intensity and severity of
fl oods and droughts in mountains as well as in their lowlands (Beniston
2005). The high intensity precipitation could trigger fl ash fl oods, slope
failure and landslides in mountainous terrains having severe impacts on the
natural and socio-economic sustainability of fragile mountain ecosystems
especially in the tropics and at higher latitudes where an increase in overall
precipitation is expected. The more intense precipitation has increased the
incidences as well as the spatial scale of fl oods in the Central Europe during
the past few decades. Since the 1990s, an increase in extreme events has
been recorded in several river systems with a probability of recurrence in
such short succession in large parts of Europe (Borsdorf et al. 2008). On
the contrary, the risks of droughts are likely to increase in most subtropical
and mid-latitude regions. The most dangerous natural disasters in high
mountains are associated with the direct consequences of changes in the
cryosphere. The changes in cryosphere have led to the formation of a large
number of glacial lakes in the Himalaya, and many of these high altitude
lakes are potentially dangerous. The resulting Glacial Lake Out Flows
(GLOFs) can cause catastrophic fl ooding in lowlands damaging human
lives, property, forests, agricultural land, crops and infrastructure. The
Himalaya in Nepal has recorded 25 GLOFs over the last 70 years (Mool
2001, Yamada 1998). In the Hindu Kush-Himalayan region, some 204 critical
glacial lakes bearing the high risk of breaching have been identifi ed (Ives
et al. 2010). It has been observed that liquid precipitation in combination
with excessive melt-water often triggers fl ash fl oods and debris fl ows. In
Karakoram ranges, the catastrophic rockslides have a substantial infl uence
on glaciers and have triggered glacial surges which are specifi c hazards
in the Karakoram and Pamir mountains (Hewitt 2005). In the Andes, the
frequency of extreme climate or weather events in Andean countries, such
as fl ooding, extreme temperatures, landslides, droughts and wildfi res have
increased by almost 40% in the period 2001-2010 (CEPAL 2011) (Table 4.5).
As discussed earlier, mountains consisting of fragile ecosystems are
highly vulnerable to the impacts of these changes that may cause substantial
loss of forests, biodiversity and natural habitats, decrease in availability
of water for drinking, sanitation and food production, and consequently
an increased proportion of water, health, food and livelihood of the
insecure population in the entire region. Moreover, the changing climatic
conditions are also expected to increase both the severity and frequency
of natural disasters in fragile mountains (IPCC 2007a,b, ICIMOD 2007a).
Climate change is particularly threatening sustainable development,