xxiv The Environmental Debate
conservation became a major issue. However, only after the dropping of the atomic bomb in 1945 and
the consequent realization by people that humans had the ability to make the earth uninhabitable did
the concept of environmentalism begin to take hold. In the second half of the twentieth century, as the
human impact on the Earth’s environment became increasingly apparent, the demand for environmental
action to sustain life on our planet intensified.
Finding acceptable solutions to environmental issues, though, has rarely been simple because peo-
ple expect the solutions to satisfy three fundamental human needs and desires: material and economic
well-being (including adequate food, clothing, and shelter), physical well-being (including health and
safety), and access to open space and other aspects of nature that enhance spiritual well-being. Pro-
posed solutions invariably arouse competing economic, social, and political interests and may bring to
the fore conflicting ethical and religious values. In recent decades as some of the most widely opposed
types of pollution have been brought under control, the forces demanding greater, unregulated access to
resources have been gaining support.
POPULATION
Environmental problems form a web, with the issue of population growth at its center. The larger the
number of people, the more land that will be occupied, the more energy that will be used, the more
resources that will be consumed, and the more waste that will be produced. How many people there are
in a finite area, how they live, and how they use resources not only affect what happens to all living things
in that particular area, but may also impinge on living things, including people, elsewhere on the planet.
The rate of human population growth often surprises those unfamiliar with population dynamics.
It took from the beginning of human existence until about 1850 for the world population to reach 1 bil-
lion people,3 and only another 80 years for it to reach 2 billion. Just 30 years later the earth contained 3
billion people. Between 1960 and 1975 the world’s population grew by another billion to 4 billion. Since
1975 it has been increasing by more than 83 million people annually, with the world population reaching
5 billion in 1987, 6 billion in 1999, 7 billion in 2011, and 7.5 billion in 2017. It is projected that by 2050
the world’s population will be more than 9.5 billion and by 2100 more than 11 billion.4 While the rate
of population growth has slowed in recent years, the actual numerical increase in population is still stag-
gering. The birth rate in several developed countries in Europe, Asia, and North America has stabilized
or is even declining, but in some of these countries a major cause of population increase is immigration
from developing and underdeveloped countries, where more than 90 percent of the world’s population
growth is occurring, as well as refugees from war-torn nations. The annual rate of population increase
in the United States, which is the highest in the industrial world, has decreased from about 1.10 percent
between 1990 and 1995 to about 0.74 percent in 2016.5
Food supply, habitat suitability, disease, and predation limit how many individual members of a par-
ticular species can live in a given ecosystem. Humans, however, have developed technologies to manipu-
late and control these factors, and as their technological abilities have advanced, their population has
been able to increase beyond the natural carrying capacity of the local environment. Although there
still are places where people die of starvation, at present there actually is sufficient food in the world
to feed everyone; today, people starve only because political, social, or economic factors prevent them
from obtaining food. While some places on our planet are unsuitable for human habitation, humans
can now live almost anywhere on Earth provided they employ sufficient, and sometimes very expensive,
technology. As we produce food more efficiently, reduce death from disease and starvation, and improve
nutrition and health care, we make it possible for more babies to be born, for more children to grow up,