Sustainable Mountain Development No. 56, ICIMOD, Winter 2009
is occurring much faster than the global average, up to 500 million tonnes of cereals per year, equivalent to
0.03ºC per year, and even faster at higher altitudes. nearly 55% of Asia’s cereal production and 25% of
Scenarios suggest that the effects on rivers are highly world production today. By 2050, as projected by
variable, ranging from a major increase in the annual FAO, global cereal production needs to be around
fl ow of the Indus until around 2050 followed by a 3000 million tonnes in order to meet demand. However,
relatively rapid decline, to a gradual decline in the fl ow due to environmental degradation in the watersheds,
in rivers such as the Brahmaputra. For rivers like the
Indus, Syr Darya, and Amu Darya, a major decline in
“Many people and farmers
the water fl ow will have devastating impacts on food
production and domestic availability, as there are few, if are already challenged by
any, alternatives to this water.
seasonal water scarcity”
With temperatures projected as continuing to rise, the
annual fl ow of the rivers will invariably decline over
fl oods, and reduced water fl ow due to climate change
time, particularly for those dependent on melting snow
in the Hindu Kush-Himalayas, cereal production in Asia
and ice, but less so for those more dependent on the
may be at least 10% to 30% lower than projected,
monsoon rains. The irrigated cropland in those basins
corresponding to a 1.7% to 5% reduction globally. Any
which are the most dependent upon the mountains for
changes in the water available for irrigation in Asia
water fl ow, comprises approximately 85,783,000 ha.
may thus have a signifi cant impact not only on cereal
The average production of irrigated rice is projected
production in selected countries and regions in Asia, but
at 6 tonnes/ha (range 2-10 tonnes/ha), compared
also on Asia’s and the world’s entire cereal production.
to 2-3 tonnes/ha for non-irrigated land (average of
both combined, about 3.3 tonnes/ha in Asia). Water In countries like Pakistan, the impacts on food production
from the Hindu Kush-Himalayas and the central Asian are likely to be far greater, and it is unlikely that the
mountain region thus supports the production of over country will be able to maintain the same level of self-
River basins and their hydrological signifi cance
Source: UNEP Global Outlook for Ice and Snow, 2007; Viviroli, D et al. (2003) Assessing the hydrological signifi cance of the world’s mountains. MRD 23:32-40
Ob
Yenisey
Amur
Lake Balkhash
Syr Darya
Tarim
Amu Darya
Huang He
(Yellow river)
Indus
H
im
ala
yas
Brahmaputra
Yangtze
Ganges
Xun Jiang
Irrawaddy
Hong
Salween
Chao
Hydrological signifi cance of
glaciers and snow for rivers Population in millions
Phraya
Mekong
Very high signifi cance
400
High signifi cance
Mekong
100
Moderate signifi cance 50
10
Low signifi cance
100
7