Environmental Engineering Reference
In-Depth Information
role in many low-income societies, particularly in Africa. And modern societies have
been engaged in ocean foraging—dominated by commercial catches of scores of i sh
species, as well as marine invertebrates and large mammals—with unprecedented
intensity as formerly low-volume and largely coastal i shing practices were trans-
formed into mass-scale and truly planetwide hunts.
Agricultural practices and the domestication of animals evolved independently
in several regions and were followed by the gradual intensii cation of traditional
cultivation that could not prevent a relatively high frequency of malnutrition and
recurrent famines. Even during the early modern era, roughly the sixteenth to the
eighteenth centuries, neither was uncommon in parts of Europe and China, economi-
cally the most advanced regions of the world. Some traditional agricultures achieved
remarkably high productivities and were able to support unprecedented population
densities; the three Asian regions come i rst to mind: China's Guangdong province,
Japan's Kant¯ Plain, and Java.
But truly revolutionary production gains came only during the twentieth century
with the massive deployment of intensive inputs that began with the introduction
of synthetic (nitrogenous and phosphatic) fertilizers and i eld machinery powered
by internal combustion engines and intensii ed after World War II with the adoption
of new cultivars, the application of herbicides and pesticides, and a wider use of
various forms of irrigation. Modern agriculture concentrated the impacts associated
with food production in areas that satisii ed at least some, if not all, preconditions
for annual or permanent cropping, and higher yields and improved productivities
in animal husbandry have reduced the amount of land, water, or nitrogen needed
to produce adequate diets: the great post-1850 agricultural revolution drastically
cut the amount of land needed to feed an average person.
But the global population growth began to accelerate after1850, and surged after
1950. The increase was driven not only by better nutrition but also by epochal
improvements in health care and the overall standard of living produced by a new
industrial-urban civilization energized by fossil fuels, using new mechanical prime
movers and turning out massive amounts of affordable material possessions, thanks
to better organized manufacturing. As a result, crop cultivation now claims a larger
share of ice-free surface than at any time in history, and the effect of rising popula-
tion numbers has been potentiated by a worldwide dietary transition whose main
feature has been a higher consumption of meat, eggs, and dairy products. Metabolic
imperatives cause unavoidable and, in the case of large ruminants, also very high
feed-to-meat conversion losses, and as a result, most of the crops produced (or
