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The Changing Himalayas
disasters in the region, but also the susceptibility of the The lack of data related to climate and water in the region
region to such events (Table 5). Climate change involves, hinders a comprehensive assessment of changes in extreme
perhaps most seriously, changes in the frequency and climatic events. Available studies suggest changes in
magnitude of extreme weather events. There is widespread climatic patterns and an increase in extreme events. An
agreement that global warming is associated with extreme increase in the frequency of high intensity rainfall often
fluctuations, particularly in combination with intensified leading to flash floods and landslides has been reported
monsoon circulations. (Chalise and Khanal 2001; ICIMOD 2007a; Figure 4). In
parts of Central Asia, regional increases in temperature will
Table 5: Top 10 Natural disasters worldwide in 2008
lead to an increased probability of events such as mudflows
by number of deaths
and avalanches that could adversely affect human
Type of disaster (month) Country Number of
settlements (Iafiazova 1997).
In the eastern and central Himalayas, glacial melt associated
Cyclone Nargis (May) Myanmar 138,366
with climate change, has led to the formation of glacial
Earthquake (May) China PR 87,476
lakes behind terminal moraines. Many of these high-altitude
Flood (June-August) India 1,963
lakes are potentially dangerous. The moraine dams are
Extreme winter conditions Afghanistan 1,317
comparatively weak and can breach suddenly, leading to
Typhoon Fengshen (Franck) Philippines 644
the sudden discharge of huge volumes of water and debris.
The resulting glacial lake outburst floods (GLOFs) can cause
Hurricane Hanna Haiti 529
catastrophic flooding downstream, with serious damage to
life, property, forests, farms, and infrastructure. In Nepal,
Mass movement wet China PR 277
twenty-five GLOFs have been recorded in the last 70 years,
Flood (October) Yemen 180 including five in the sixties and four in the eighties (Mool,
Flood (June) China PR 176 2001; NEA, 2004; Yamada, 1998). There is an indication
Flood (September) India 173 that the frequency of GLOF events has increased in recent
229784 decades (Figure 4). In the HKH region two hundred and four
Source: UNISDR 2008 glacial lakes have been identified as potentially dangerous
which can burst at any time (ICIMOD 2007b).
Consequences for Livelihoods
and the Environment
Figure 4: Cumulative occurrence of GLOFs in Nepal
Pastures and Agriculture
(top, source NEA 2004) and flash floods in the greater
Himalayan region (bottom, source Xu Jianchu et al. 2007)
The location and area of natural vegetation zones on the
Tibetan Plateau will change substantially under projected
climate change scenarios. Areas of temperate grassland
and cold temperate coniferous forest could expand,
while temperate and cold deserts may shrink. The vertical
distribution of vegetation zones could move to higher
altitude. Climate change may also result in a shift of the
boundary of the farming-pastoral transition region to the
south in Northeast China, which may increase grassland
areas and provide more favourable conditions for livestock
production. However, the transition area of the farming-
pastoral region is also an area of potential desertification,
and if protection measures are not taken in new transition
areas, desertification may occur (Li and Zhou 2001; Qiu
et al. 2001). More frequent and prolonged droughts as
a consequence of climate change together with other
Cumulative occurrence of GLOFs
anthropogenic factors may also result in desertification.
There is significant uncertainty about the effects of global
warming on the vegetation and animal productivity of
large dryland ecosystems. Although high altitude drylands
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