Regional Impacts - Climate Resilient Agriculture for Ensuring Food Security - page 94

• Fish breeding habitats, fi sh food supply, and,
ultimately, the abundance of fi sh populations
in Asian waters will be substantially altered.
Aquaculture industry and infrastructure,
particularly in heavily populated mega deltas,
are likely to be seriously affected by coastal
inundation.
Asia is a region where water distribution is
uneven and large areas are under water stress.
Among the 43 countries of Asia, 20 have renew-
able annual per capita water resources in excess
of 3,000 m 3 , 11 are between 1,000 and 3,000 m 3 ,
and 6 are below 1,000 m 3 (there are no data from
the remaining 6 countries). From west China and
Mongolia to west Asia, there are large areas of
arid and semiarid lands. Even in humid and
subhumid areas of Asia, water scarcity/stress is
one of the constraints for sustainable develop-
ment. On the other hand, Asia has a very high
population that is growing at a fast rate, low
development levels, and weak coping capacity.
Climate change is expected to exacerbate the
water scarcity situation in Asia, together with
multiple socioeconomic stresses.
Production of rice, maize, and wheat in the
past few decades has declined in many parts of
Asia due to increasing water stress, arising partly
from increasing temperatures, increasing frequency
of El Niño events, and reductions in the number
of rainy days.
In East and Southeast Asia, the IPCC ( 2007 )
projected that crop yields could increase up to
20 % by the mid-twenty-fi rst century. In Central
and South Asia, projections suggested that yields
might decrease by up to 30 %, over the same time
period. These projections were assigned “medium
confi dence.” Taken together, the risk of hunger
was projected to remain very high in several
developing countries.
More detailed analysis of rice yields by the
International Rice Research Institute forecasts
20 % reduction in yields over the region per 1 °C
of temperature rise. Rice becomes sterile if
exposed to temperatures above 35 °C for more
than 1 h during fl owering and consequently
produces no grain.
Agricultural irrigation demand in arid and
semiarid regions of Asia is estimated to increase

by at least 10 % for an increase in temperature of
1 °C. Rainfed crops in the plains of north and
northeast China could face water-related chal-
lenges in future decades due to increases in water
demand and soil-moisture defi cit associated with
projected declines in precipitation. However, that
more than two-thirds of the models ensembled
show an increase in precipitation and runoff for
this region. In north China, irrigation from sur-
face water and groundwater sources is projected
to meet only 70 % of the water requirement
for agricultural production, due to the effects of
climate change and increasing demand. Enhanced
variability in hydrological characteristics will be
likely to continue to affect grain supplies and
food security in many nations of Asia.

5.2.1 Adaptation and Vulnerability

There are different current water vulnerabilities
in Asian countries. Some countries which are not
currently facing high risk are expected to face a
future risk of water stress, with various capacities
for adaptation. Coastal areas, especially heavily
populated mega delta regions in South, East, and
Southeast Asia, are expected to be at greatest
risk of increased river and coastal fl ooding. In
southern and eastern Asia, the interaction of climate
change impacts with rapid economic and popula-
tion growth, and migration from rural to urban
areas, is expected to affect development.
The vulnerability of a society is infl uenced
by its development path, physical exposures, the
distribution of resources, prior stresses, and
social and government institutions. All societies
have inherent abilities to deal with certain variations
in climate, yet adaptive capacities are unevenly
distributed, both across countries and within soci-
eties. The poor and marginalized have historically
been most at risk and are most vulnerable to the
impacts of climate change. Recent analyses in
Asia show that marginalized, primary-resource-
dependent livelihood groups are particularly
vulnerable to climate change impacts if their natu-
ral resource base is severely stressed and degraded
by overuse or if their governance systems are not
capable of responding effectively.