Climate Change, Global Warming, and Agricultural Droughts - Monitoring and Predicting Agricultural Drought: A Global Study - page 438

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Figure 34.2 Variability in wheat yield in Bulgaria as expressed by (a) S -aridity index and (b)
an nual variability; bold solid lines represent trends.

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in 1968, 1969, 1971, 1978, 1979, 1983, 1984, and 1985 in Lebanon; in
19 70, 1973, 1975, 1976, 1977, 1978, 1979, 1981, 1982, 1985, and 1986
in Jordan; in 1970, 1973, 1977, 1982, 1982, 1986, and 1991 in Cyprus;
an d in 1970, 1976, 1979, 1982, and 1984 in Sudan. However, in Egypt and
Ir an, a severe drought occurred only once, although the average anomaly
of the wheat production in these countries was also negative.

Line
——
-0.0
——
Long
PgEn

So uthern Hemisphere

Fi gure 34.5 shows the results of the yield anomalies for some Southern
H emisphere countries for last 40 years. It is interesting to note that in
th ese main grain-producing areas of the Southern Hemisphere the changes
in the wheat yields followed a common pattern. In South Africa, Namibia,
A ustralia, New Zealand, Argentina, and Uruguay, the beginning and end
of the negative phase of the wheat yield anomalies fall approximately in
th e same years: 1970 and 1995. During this period, drought (causing yield
re duction of 20% or more from the normal) occurred in 1978, 1980, 1983,
19 85, 1989, 1990, and 1995 in South Africa; in 1977, 1978, 1985, 1986,
19 87, and 1988 in Namibia; in 1972, 1977, 1980, 1982, and 1994 in
A ustralia; and in 1970 and 1989 in New Zealand. In Argentina negative
w heat yield anomalies occurred during 1970-95, and droughts occurred in
19 68 and 1981. In Uruguay drought occurred in 1976, 1977, 1978, 1985,
19 86, and 1993.
Having noted that the regularities in the variation of wheat production
an omalies in different geographical regions in recent years, we now turn
ou r attention to the question of whether the results obtained could be used
fo r prediction purposes—to extrapolate these trends for the years ahead.

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Th e Possible Impact of Future Climate Changes
on the Occurrence of Droughts
For predicting the effect of droughts on agriculture in a given region, one
needs to have a completely reliable and detailed climatic forecast for that