Impacts of Climate Change on Agriculture - Climate Resilient Agriculture for Ensuring Food Security - page 70

for feed at the very moment when there is less
feed available. Increased demand drives a feed
price increase, which forces livestock owners to
sell their cattle. Massive sales while there is a
reduced demand push down cattle prices, forcing
livestock owners to sell even more to buy feed.
These effects on prices reduce farm and house-
hold income and assets. Moreover, they reduce
the value of assets (livestock) and productive
capital for the future. Prolonged or repeated
drought also has long-lasting degrading effects on
land. The combination of drought and overgraz-
ing, particularly near watering points, destroys
the vegetal cover and increases soil erosion.

damage to vegetables by fl ooding is due to
reduction of oxygen in the root zone, which
inhibits aerobic processes. Flooded tomato plants
accumulate endogenous ethylene that causes
damage to the plants (Drew 1979 ). The rapid
development of epinastic growth of leaves is a
characteristic response of tomatoes to water-
logged conditions, and the role of ethylene accu-
mulation has been implicated (Kawase 1981 ).
The severity of fl ooding symptoms increases
with rising temperatures; rapid wilting and death
of tomato plants is usually observed following a
short period of fl ooding at high temperatures
(Kuo et al. 1982 ).

4.6.3 Heavy Rainfall and Flooding 4.6.4 Tropical Storms

Food production can also be impacted by too
much water. Heavy rainfall events leading to
fl ooding can wipe out entire crops over wide
areas, and excess water can also lead to other
impacts including soil water logging, anaerobic-
ity, and reduced plant growth. Indirect impacts
include delayed farming operations. Agricultural
machinery may simply not be adapted to wet soil
conditions. In a study looking at the impacts of
current climate variability, the heavy rainfall in
August was linked to lower grain quality which
leads to sprouting of the grain in the ear and fun-
gal disease infections of the grain. This was
shown to affect the quality of the subsequent
products such that it infl uenced the amount of
milling wheat that was exported from the
UK. The proportion of total rain falling in heavy
rainfall events appears to be increasing, and this
trend is expected to continue as the climate con-
tinues to warm. A doubling of CO 2 is projected to
lead to an increase in intense rainfall over much
of Europe. In the higher-end projections, rainfall
intensity increases by over 25 % in many areas
important for agriculture.
Crop production is often limited during the
rainy season due to excessive moisture brought
about by heavy rains. Most vegetables are highly
sensitive to fl ooding, and genetic variation with
respect to this character is limited, particularly in
tomato and early caulifl ower. In general, the

Climate models do not do a good job of predict-
ing how extreme weather events might change
under global warming. For example, models do
not agree on whether the number of hurricanes in
a warmer world would be more or less than cur-
rent values, but scientists generally feel that the
strength of the largest hurricanes will increase.
The length of the hurricane season could also
increase. Observational changes in the number of
tornadoes per year we see now may be due to
increases in the number of people watching the
skies and the growth of urban areas rather than
any strict climate changes. It is not clear if
observed changes in extreme weather events we
see now are part of long natural cycles, or if they
are in response to climate change. Nonetheless,
all of these events can be detrimental to crop
growth. The most vulnerable agricultural regions
for tropical cyclones are found, among others, in
the USA, China, Vietnam, India, Bangladesh,
Myanmar, and Madagascar.
Both societal and economic implications of
tropical cyclones can be high, particularly in
developing countries with high population
growth rates in vulnerable tropical and subtropi-
cal regions. This is particularly the case in the
North Indian Ocean, where the most vulnerable
people live in the river deltas of Myanmar,
Bangladesh, India, and Pakistan; here population
growth has resulted in increased farming in