Environmental Engineering Reference
In-Depth Information
Farmers typically cultivate fields to remove weeds and apply fertilizer with planted
seeds in order to maximize germination and early growth. Cultivation and planting
occurs in the spring when strong winds are common. Soil organics near the surface that
have absorbed the applied agricultural chemicals are carried from rural to urban areas
where pollution impacts large populations.
A new ecological design for food crops is needed, conserved, and reused rather than
consuming fossil natural resources. The ecology of this new food source would provide
substantial benefit if it did not require fertile soils, freshwater, and fossil fuels and did not
generate agricultural pollution.
24.5 Climate Change
Many scientists, including James Hansen at NASA, believe that global warming is accel-
erating and may be approaching a tipping point where climate change acquires a momen-
tum that makes it irreversible. The consensus is that we may have a decade to turn the
situation around before this threshold is crossed. 23
Global warming that included drought, wildfires, and fierce storms was largely respon-
sible for food price spikes in 2008 which caused food riots in 40 countries. These insur-
rections disrupted national economies, spurred food theft, and resulted in hundreds of
deaths. Several countries created policies that prohibited food hoarding, waste, and even
exports.
Secretary of Energy and Nobel-Prize-winning physicist Steven Chu said in his first inter-
view as secretary that California's farms and vineyards could vanish by the end of the cen-
tury and its major cities could be in jeopardy if Americans do not act to slow the advance
of global warming. 24 He also predicted that 90% of the Sierra Nevada snow pack on which
California cities and agriculture depends would be gone by the end of the century.
More heat will compound food insecurity caused by variable rainfall and will increase the
incidence of agricultural droughts caused by elevated evaporation from soils, transpiration
from plants, low soil moisture, and high rates of water runoff from hard pan soils when it
rains. Excess heat causes virga—rain that evaporates before it hits the ground. The challenges
to food and biofuel production from global warming are summarized in Table 24.2.
A new ecological design is needed for production of food and biofuels that is effective
in spite of climate chaos.
24.6 Addressing the Goal of Abundant Agriculture
Green solar energy captured in algae represent an agriculture of abundance based on
cheap natural resources that will not run out, sunshine, wastewater, and CO 2 (Figure 24.4).
Green solar employs photosynthesis to store solar energy in carbon molecules in algal plant
chemical bonds. Depending on the species, algae may be 60% by weight food energy for
people, nutrient energy for plants, or fuel energy for vehicles. Green solar has no growing
season since it grows so fast that about half of the biomass may be harvested daily. Most
species have a preferred production period which typically corresponds to land plants but
 
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