Impact on agricultureand foodsupply 165There is enormous capacity for adaptation in the growth of crops for
food – as is illustrated by what was called the Green Revolution of the
1960s, when the development of new strains of many species of crops
resulted in large increases in productivity. Between the mid 1960s and
the mid 1980s global food production rose by an average annual rate
of 2.4% – faster than global population – more than doubling over that
thirty-year period. Grain production grew even faster, at an annual rate
of 2.9%.^34 There are concerns that factors such as the degradation of
many of the world’s soils largely through erosion and the slowed rate of
expansion of irrigation because less fresh water is available will tend to
reduce the potential for increased agricultural production in the future.
However, with declining rates of population growth, there remains opti-
mism that, in the absence of major climate change, the growth in world
food supply is likely to continue to match the growth in demand at least
during the early decades of the twenty-first century.^35
What will be the effect of climate change on agriculture and food sup-
ply? With the detailed knowledge of the conditions required by different
species and the expertise in breeding techniques and genetic manipula-
tion available today, there should be little difficulty in matching crops to
new climatic conditions over large parts of the world. At least, that is the
case for crops that mature over a year or two. Forests reach maturity over
much longer periods, from decades up to a century or even more. The
projected rate of climate change is such that, during this time, trees may
find themselves in a climate to which they are far from suited. The tem-
perature regime or the rainfall may be substantially changed, resulting in
stunted growth or a greater susceptibility to disease and pests. The im-
pact of climate change on forests is considered in more detail in the next
section.
An example of adaptation to changing climate is the way in which
farmers in Peru adjust the crops they grow depending on the climate
forecast for the year.^36 Peru is a country whose climate is strongly influ-
enced by the cycle of El Ni ̃no events described in Chapters 1 and 5. Two
of the primary crops grown in Peru, rice and cotton, are very sensitive
to the amount and the timing of rainfall. Rice requires large amounts
of water; cotton has deeper roots and is capable of yielding greater pro-
duction during years of low rainfall. In 1983, following the 1982–3 El
Ni ̃no event, agricultural production dropped by fourteen per cent. By
1987 forecasts of the onset of El Ni ̃no events had become sufficiently
good for Peruvian farmers to take them into account in their planning.
In 1987, following the 1986–7 El Ni ̃no, production actually increased
by three per cent, thanks to a useful forecast.
Three factors are particularly important in considering the effect
of climate change on agriculture and food production. The availability