Impacts of Climate Change on Agriculture - Climate Resilient Agriculture for Ensuring Food Security - page 82

in runoff will affect the ability to irrigate crops
and will reduce summer stream fl ows necessary to
keep dams and reservoirs replenished.
Approximately 2.4 billion people live in the
drainage basin of the Himalayan Rivers. The River
Ganges could provide water for drinking and
farming for more than 500 million people in India,
China, Pakistan, Afghanistan, Bangladesh, Nepal,
and Myanmar. The west coast of North America,
which gets much of its water from glaciers in
mountain ranges such as the Rocky Mountains and
Sierra Nevada, also would be affected.
Satellite observations show the Arctic sea ice
is decreasing, and projections for the rest of the
century predict even more shrinkage.

expected to be enhanced further leading to
eventual decline in runoff, although the greater
time scale of this decline is uncertain.
Analysis of glaciers in the western Himalayas
demonstrates evidence of glacial thinning. The
limited number of direct observations also sup-
ports evidence of a glacial retreat in the Himalayas.

4.15 ENSO Effects on Agriculture

ENSO (El Niño Southern Oscillation) will affect
monsoon patterns more intensely in the future as
climate change warms up the ocean's water.
Crops that lie on the equatorial belt or under the
tropical Walker circulation, such as rice, will be
affected by varying monsoon patterns and more
unpredictable weather. Scheduled planting and
harvesting based on weather patterns will become
less effective.
Areas such as Indonesia where the main crop
consists of rice will be more vulnerable to the
increased intensity of ENSO effects in the future
of climate change. University of Washington pro-
fessor David Battisti researched the effects of
future ENSO patterns on the Indonesian rice agri-
culture using IPCC's 2007 annual report (UN
Environment Program 2008) and 20 different
logistical models mapping out climate factors
such as wind pressure, sea level, and humidity and
found that rice harvest will experience a decrease
in yield. Bali and Java, which holds 55 % of the
rice yields in Indonesia, will be likely to experi-
ence 9-10 % probably of delayed monsoon pat-
terns, which prolongs the hungry season. Normal
planting of rice crops begins in October and har-
vest by January. However, as climate change
affects ENSO and consequently delays planting,
harvesting will be late and in drier conditions,
resulting in less potential yields (Brown 2005 ).

4.14.1 Changes in Water Availability

In some rivers such as the Nile, climate change
increases fl ow throughout the year which could
confer benefi ts to agriculture. However, in other
catchments, e.g., the Ganges, the increase in run-
off comes as an increase in peak fl ow around the
monsoon. However, dry season river fl ow is still
very low. Without suffi cient storage of peak sea-
son fl ow, water scarcity may affect agricultural
productivity despite overall increases in annual
water availability. Increases at peak fl ow may also
cause damage to crop lands through fl ooding.
Although additional river fl ow can be consid-
ered benefi cial to agriculture, this is only true if
there is an ability to store runoff during times of
excess to use later in the growing season.
Globally, only a few rivers currently have ade-
quate storage to cope with large shifts in season-
ality of runoff. Where storage capacities are not
suffi cient, much of the winter runoff will imme-
diately be lost to the oceans.
The majority of observed glaciers around the
globe are undergoing shrinkage. There is a broad
consensus that warming is a primary cause of
retreat, although changes in atmospheric moisture
particularly in the tropics may be contributing
(Bates et al. 2008 ). Melting glaciers will initially
increase river fl ow, although the seasonality of
fl ow will be enhanced bringing with it an increased
fl ood risk. In the long term, glacial retreat is

4.16 Climate Change Impacts

on Food Security

FAO defi nes food security in four dimensions,
namely, food availability, access to food, stability
of food supply, and utilization of food. This goes