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11.4.2 Food
In the preceding section, we have addressed the knock-on impacts on food production from climate impacts on the water cycle. Here we will look at other impacts of
food production and food systems. While climate impacts on food security are most
significant in terms of production, there are many other climate impacts of the food
system. It is important to remember that, as noted in Sect. 3.2, food security depends
on a wide range of factors unrelated to climate, including demographics and diet.
11.4.2.1 Climate Change Impacts on Food Production
Most food production does not occur in controlled climates (e.g., greenhouses). As
such, crops are selected with recognition of seasonal variations in temperature, sunlight, rainfall, and other climatic conditions. Other local factors such as soils, terrain, pests, availability of irrigation, other inputs, and socioeconomic consideration
also impact choices of a crop. Some changes will be regional in scale, such as a
warming climate making the best location for some crops farther north, causing
some pests to move into or out of a region. Other changes may be very local such as
a localized decrease in soil moisture or availability of irrigation water. As the climate changes, decisions about the most appropriate crop will be impacted.
Increased atmospheric carbon dioxide (CO 2 ) generally stimulates plant growth
because it increases photosynthesis. However, the size of the effect is cropdependent. There is a more significant effect on some crops such as wheat, rice,
cotton, soybean, sugar beets, and potatoes than on other crops such as corn, sorghum, and sugarcane. The size of the effect is also impacted by the influence of
water, nutrients, temperature, weeds, and parasites.
However, CO 2 emissions are usually accompanied by other pollutants (e.g.,
hydrocarbons and nitrogen oxide emitted from vehicles and power plants), which
interact with ultraviolet radiation in the lower atmosphere to create ozone (O 3 ). In
addition to being a human health hazard, elevated levels of ozone reduce plant photosynthesis and retard plant growth. Unsurprising, where steps have been taken to
reduce air pollution in wealthier nations, ozone impacts on crops are less than in
rapidly developing nations where pollution reduction technologies are deployed to
a lesser degree and local air pollution a significant problem.
Elevated O 3 since preindustrial times has very likely suppressed global production of major
crops compared to what they would have been without O 3 increases, with estimated losses
of roughly 10% for wheat and soybean and 3 to 5% for maize and rice. Impacts are most
severe over India and China but are also evident for soybean and maize in the USA.
Food crops and farm animals are sensitive to weather extremes such as high and
low temperatures, rainfall, hail, flooding, and wind. Impacts depend on the particular crop or animal and the intensity and duration of the extreme. Local geographic
factors are, as always, important.
Climate change will also impact food production through changes in agricultural
pests. Pests include weeds, fungi, beetles, moths, mice and rats, birds, and many other
P. Saundry
11.4.2 Food
In the preceding section, we have addressed the knock-on impacts on food production from climate impacts on the water cycle. Here we will look at other impacts of
food production and food systems. While climate impacts on food security are most
significant in terms of production, there are many other climate impacts of the food
system. It is important to remember that, as noted in Sect. 3.2, food security depends
on a wide range of factors unrelated to climate, including demographics and diet.
11.4.2.1 Climate Change Impacts on Food Production
Most food production does not occur in controlled climates (e.g., greenhouses). As
such, crops are selected with recognition of seasonal variations in temperature, sunlight, rainfall, and other climatic conditions. Other local factors such as soils, terrain, pests, availability of irrigation, other inputs, and socioeconomic consideration
also impact choices of a crop. Some changes will be regional in scale, such as a
warming climate making the best location for some crops farther north, causing
some pests to move into or out of a region. Other changes may be very local such as
a localized decrease in soil moisture or availability of irrigation water. As the climate changes, decisions about the most appropriate crop will be impacted.
Increased atmospheric carbon dioxide (CO 2 ) generally stimulates plant growth
because it increases photosynthesis. However, the size of the effect is cropdependent. There is a more significant effect on some crops such as wheat, rice,
cotton, soybean, sugar beets, and potatoes than on other crops such as corn, sorghum, and sugarcane. The size of the effect is also impacted by the influence of
water, nutrients, temperature, weeds, and parasites.
However, CO 2 emissions are usually accompanied by other pollutants (e.g.,
hydrocarbons and nitrogen oxide emitted from vehicles and power plants), which
interact with ultraviolet radiation in the lower atmosphere to create ozone (O 3 ). In
addition to being a human health hazard, elevated levels of ozone reduce plant photosynthesis and retard plant growth. Unsurprising, where steps have been taken to
reduce air pollution in wealthier nations, ozone impacts on crops are less than in
rapidly developing nations where pollution reduction technologies are deployed to
a lesser degree and local air pollution a significant problem.
Elevated O 3 since preindustrial times has very likely suppressed global production of major
crops compared to what they would have been without O 3 increases, with estimated losses
of roughly 10% for wheat and soybean and 3 to 5% for maize and rice. Impacts are most
severe over India and China but are also evident for soybean and maize in the USA.
Food crops and farm animals are sensitive to weather extremes such as high and
low temperatures, rainfall, hail, flooding, and wind. Impacts depend on the particular crop or animal and the intensity and duration of the extreme. Local geographic
factors are, as always, important.
Climate change will also impact food production through changes in agricultural
pests. Pests include weeds, fungi, beetles, moths, mice and rats, birds, and many other
P. Saundry