Regional Impacts - Climate Resilient Agriculture for Ensuring Food Security - page 93

their resource base - already severely stressed
and degraded by overuse - is expected to be
further impacted by climate change.
Climate change and variability have the
potential to impose additional pressures on water
availability, accessibility, supply, and demand in
Africa. It is estimated that around 25 % (200 mil-
lion) of Africa's population currently experiences
water stress, with more countries expected to face
high future risk. Moreover, it has been envisioned
that, even without climate change, several coun-
tries, particularly in northern Africa, would reach
the threshold level of their economically usable
land-based water resources before 2025.
Frequent natural disasters, such as droughts
and fl oods, have largely constrained agricultural
development in Africa, which is heavily depen-
dent on rainfall, leading to food insecurity in
addition to a range of macro- and microstructural
problems.
ENSO has a signifi cant infl uence on rainfall at
interannual scales in Africa and may infl uence
future climate variability. However, a number of
barriers hamper effective adaptation to variations
in ENSO including spatial and temporal uncer-
tainties associated with forecasts of regional cli-
mate, the low level of awareness among decision
makers of the local and regional impacts of El
Niño, limited national capacities in climate mon-
itoring and forecasting, and lack of coordination
in the formulation of responses.
Regarding the impacts of climate variability
and change on groundwater, little information
is available, despite many countries (especially in
northern Africa) being dependent on such water
sources.
Previous assessments of water impacts have
not adequately covered the multiple future water
uses and future water stress, and so more detailed
research on hydrology, drainage, and climate
change is required. Future access to water in
rural areas, drawn from low-order surface water
streams, also needs to be addressed by countries
sharing river basins.
Adaptive capacity and adaptation related to
water resources are considered very important to
the African continent. Historically, migration in
the face of drought and fl oods has been identifi ed

as one of the adaptation options. Migration has
also been found to present a source of income for
those migrants who are employed as seasonal
labor. Other practices that contribute to adapta-
tion include traditional and modern water-
harvesting techniques, water conservation and
storage, and planting of drought-resistant and
early-maturing crops. The importance of building
on traditional knowledge related to water har-
vesting and use has been highlighted as one of
the most important adaptation requirements,
indicating the need for its incorporation into
climate change policies to ensure the development
of effective adaptation strategies that are cost-
effective, participatory, and sustainable.
Very little information exists regarding the
cost of impacts and adaptation to climate change
for water resources in Africa. However, an initial
assessment in South Africa of adaptation costs in
the Berg River Basin shows that the costs of not
adapting to climate change can be much greater
than those that may arise if fl exible and effi cient
approaches are included in management options
(Stern 2007 ).

5.2 Asia

• Crop yield decreases in many areas will put
many millions of Asians at risk from hunger.
• Water stress will affect more than 100 million
people due to decrease of freshwater avail-
ability in Central, South, East and Southeast
Asia, particularly in large river basins such as
Changjiang.
• Land degradation and desertifi cation may
increase due to reduced soil moisture and
increased evapotranspiration. Grassland pro-
ductivity is expected to decline by as much as
40-90 % with a temperature increase of
2-3 °C, combined with reduced precipitation
in the semiarid and arid regions.
• Agriculture productivity may expand in
northern areas.
• Boreal forest in north Asia may increase
northward, although the likely increase in
frequency and extent of forest fi res could limit
forest expansion.