Background:
Globally, the 20th century was marked by: (a) two devastating world
wars; (b) the Great Depression of the 1930s; (c) the end of vast
colonial empires; (d) rapid advances in science and technology, from
the first airplane flight at Kitty Hawk, North Carolina (US) to the
landing on the moon; (e) the Cold War between the Western alliance
and the Warsaw Pact nations; (f) a sharp rise in living standards in
North America, Europe, and Japan; (g) increased concerns about the
environment, including loss of forests, shortages of energy and
water, the decline in biological diversity, and air pollution; (h)
the onset of the AIDS epidemic; and (i) the ultimate emergence of
the US as the only world superpower. The planet's population
continues to explode: from 1 billion in 1820, to 2 billion in 1930,
3 billion in 1960, 4 billion in 1974, 5 billion in 1988, and 6
billion in 2000. For the 21st century, the continued exponential
growth in science and technology raises both hopes (e.g., advances
in medicine) and fears (e.g., development of even more lethal
weapons of war).