Environmental Engineering Reference
In-Depth Information
Temperature
An increase in average temperature can lengthen the
growing season, adversely affect crops in regions where summer heat
already limits production, increase soil evaporation rates, and increase
the chances of severe droughts.
Rainfall
Changes in rainfall can affect soil erosion rates and soil mois-
ture, both of which are important for crop yields. Predicting future
changes in rainfall, whether in total amount or intensity, is impossible,
especially at regional scales.
Carbon dioxide fertilization
Increases in carbon dioxide levels can
boost the growth of most crops. But this benefi cial effect can be either
strengthened or weakened depending on temperature effects and nutrient
availability. Unfortunately, increased carbon dioxide also benefi ts weed
growth.
Smog
Higher smog levels limit the growth of crops. Ozone levels near
the ground are determined by both auto emissions and temperature. Such
changes may offset any benefi cial yield effects that result from elevated
carbon dioxide levels.
Climatic variability and extreme events
Changes in the frequency and
severity of heat waves, drought, fl oods, and hurricanes are an important
uncertainty about future climate change. Such changes are anticipated
but their effects are uncertain.
There will no doubt be signifi cant regional transitions associated with
shifts in agriculture as a result of climate change. Some areas of the
agricultural belt will benefi t, and others will suffer declining yields, but
agriculture in developed countries is less vulnerable to climate change
than agriculture in developing nations is, especially in the tropics, where
farmers may have limited ability to adapt.
Can Terrorists Harm Our Food Supply?
We live in a world in which terrorism is a threat. The weapons used have
been mostly those common throughout human history, upgraded from
clubs and crossbows to hand-held fi rearms to missiles, bombs, and other
explosives.
One weapon that has not yet been used but may well be on the
horizon is bioterrorism, the sabotage of a nation's health or food supply,
a topic explored in some depth in a recent topic.
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Plant killers of various
kinds abound, they act quickly, and many of them are unaffected by
our existing array of poisons. A new strain of the potato blight that
caused the famine in Ireland in the 1840s hit North America in 1994
