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The Changing Himalayas
or more in the Indus (Tarar 1982), and 30% in the major to the negative effect of rising temperatures. It is projected
rivers in Nepal during the pre-monsoon season (Sharma that the spread of malaria, Bartonellosis, tick-borne diseases
1993), the implications of dry season water stress are likely and infectious diseases linked to the rate of pathogen
to be massive. In addition, an increase in agricultural water replication will all be enhanced. Malaria mosquitoes have
demand by 6 to 10% or more is projected for every 1°C recently been observed at high altitudes in the region
rise in temperature (IPCC 2007a). As a result, the net cereal (Eriksson et al. 2008).
production in South Asian countries is projected to decline
by at least between 4 to 10% by the end of this century,
Endemic morbidity and mortality due to diarrhoeal disease
under the most conservative climate production projections
associated with floods and droughts are expected to rise in
(IPCC 2007a).
East, South and Southeast Asia due to projected changes
in the hydrological cycle (IPCC 2007a). This will be in
addition to an already very high global burden of climate
Ecosystems
change attributable diarrhoea. Empirical studies project that
Mountain ecosystems contain a series of climatically very
the population at risk of dengue fever will be larger in India
different zones within short distances and elevations. They
and China. In these countries, a high increase in mortality
display a range of micro-habitats with great biodiversity
due to heat stress is also projected.
(Körner 2004). Mountain ecosystems are sensitive to
However, there are also expected to be positive climate
global warming and show signs of fragmentation and
change induced effects on the health status of certain
degradation (Xu and Wilkes 2004; Körner 2004). Species
populations in the Himalayan region. High altitude areas
in high-elevation ecosystems are projected to shift to higher
will open up to new types of agricultural production and
altitudes, although alpine plant species with restricted
new livelihood opportunities, people will find their homes
habitat availability above the tree line are projected to
and villages more comfortable due to less cold conditions,
experience severe fragmentation, habitat loss, or even
and the risks associated with cold and respiratory diseases
extinction if they cannot move to higher elevations (Dirnbock
will be reduced as the use of fuelwood for heating is
et al. 2003). Climate warming may increase suitable
reduced.
habitats for the water hyacinth (Eichhornia crassipes), a
noxious weed able to survive winter temperatures.
Mountain Infrastructure
The impacts of climate change on forest ecosystems include
shifts in the latitude of forest boundaries and the upward
Valuable infrastructure, such as hydropower plants, roads,
movement of tree lines to higher elevations; changes in
bridges, and communication systems, will be increasingly
species’ composition and in vegetation types; and an
at risk from climate change. Entire hydropower generation
increase in net primary productivity (NPP) (Ramakrishna et
systems established on many rivers will be in jeopardy
al. 2003). In the eastern Himalayas, forest vegetation will
if landslides and flash floods increase, and hydropower
expand significantly; forest productivity will increase from 1
generation will be affected if there is a decrease in the
to 10%; and it is expected that forest fires and pests such as
already low flows during the dry season. Engineers will
the North American pinewood nematode (Bursaphelenchus
have to consider how to respond to these challenges
xylophilus) will increase as dryness and warmth increase
(OECD 2003).
(Rebetez and Dobbertin 2004).
A specific hazard related to glacier retreat are the formation
of pro-glacial lakes and in some cases the events of glacial
Human Health
lake outburst floods (GLOFs). These can have a devastating
effect on important and vulnerable infrastructure downstream
The impact of climate change on health conditions can
such as hydropower stations. Equally important, the
be broken into three main categories: (i) direct impacts of
operations of hydroelectric power stations will become
for example, drought, heat waves, and flash floods, (ii)
more complex. With climate change, the complexity and
indirect effects due to climate-induced economic dislocation,
variability of river flow generation will both rise (Renoj et
decline, conflict, crop failure, and associated malnutrition
al. 2007) and become increasingly difficult to predict.
and hunger, and (iii) indirect effects due to the spread and
For example, although the annual average proportion of
aggravated intensity of infectious diseases due to changing
meltwater in river flow has been estimated at 13% for rivers
environmental conditions (WHO 2005). The latter effect
flowing to the Ganges from Nepal, from March through
includes the expansion of vector-borne diseases such as
May the monthly average proportion is more than 30%
malaria and dengue and water-related diseases such as
(Chaulagain 2006). This could have serious implications on
diarrhoea. Regions such as the Hindu Kush-Himalayas,
river flows and water availability for power plants for about
located at the fringe of the current geographic distribution of
six months per year.
these and many other diseases, are particularity susceptible
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