476 Glossary
environmental science The interdisciplinary study of humanity’s
relationship with other organisms and the physical environment.
environmental worldview A worldview based on how the
environment works, our place in the environment, and right and
wrong e nvironmental behaviors.
epidemiology The study of the effects of chemical, biological, and
physical agents on the health of human populations.
estuary A coastal body of water, partly surrounded by land, with
access to the open ocean and a large supply of fresh water from
a river.
evolution The cumulative genetic changes in populations that occur
during successive generations.
exponential population growth The accelerating population
growth that occurs when optimal conditions allow a constant
reproductive rate.
external cost A harmful environmental or social cost that is borne by
people not directly involved in selling or buying a product.
extinction The elimination of a species from Earth.
first law of thermodynamics A physical law which states that energy
cannot be created or destroyed, although it can change from one
form to another.
fission The splitting of an atomic nucleus into two smaller fragments,
accompanied by the release of a large amount of energy.
flowing-water ecosystem A freshwater ecosystem such as a river or
stream in which water flows in a current.
fluidized-bed combustion A clean-coal technology in which crushed
coal is mixed with limestone to neutralize acidic compounds
produced during combustion.
food insecurity The condition in which people live with chronic
hunger and malnutrition.
forest decline A gradual deterioration and eventual death of many
trees in a forest.
freshwater wetlands Lands that shallow fresh water covers for at
least part of the year; wetlands have a characteristic soil and
water- tolerant vegetation.
fuel cell A device that directly converts chemical energy into
electricity. A fuel cell requires hydrogen and oxygen from
the air.
genetic engineering The manipulation of genes (for example, taking
a specific gene from one species and placing it into an unrelated
species) to produce a particular trait.
genetic resistance An inherited characteristic that decreases the
effect of a given agent (such as a pesticide) on an organism (such
as a pest).
geothermal energy Energy from Earth’s hot interior, used for space
heating or generation of electricity.
germplasm Any plant or animal material that may be used in
breeding.
green chemistry A subdiscipline of chemistry in which commercially
important chemical processes are redesigned to significantly
reduce environmental harm.
greenhouse gases Gases—including water vapor, carbon dioxide,
methane, and certain other gases—that absorb infrared
radiation.
groundwater The supply of fresh water under Earth’s surface that is
stored in underground aquifers.deep ecology worldview A worldview based on harmony with
nature, a spiritual respect for life, and the belief that humans and
all other species have an equal worth.
deforestation The temporary or permanent clearance of large
expanses of forest for agriculture or other uses.
degradation (of land) Natural or human-induced reduction in the
potential ability of the land to support crops or livestock.
demographics The applied branch of sociology that deals with
population statistics.
demographic transition The process whereby a country moves from
relatively high birth and death rates to relatively low birth and
death rates.
desert A biome in which the lack of precipitation limits plant growth;
deserts are found in both temperate and tropical regions.
desertification Degradation of once-fertile rangeland or tropical dry
forest into nonproductive desert.
dose–response curve In toxicology, a graph that shows the effects of
different doses on a population of test organisms.
dust dome A dome of heated air that surrounds an urban area and
contains a lot of air pollution.
ecological niche The totality of an organism’s adaptations, its use of
resources, and the lifestyle to which it is fitted.
ecological succession The process of community development over
time, which involves species in one stage being replaced by
different species.
ecology The study of the interactions among organisms and
between organisms and their abiotic environment.
economic development An expansion in a region’s or country’s
economy, viewed by many as the best way to raise the standard
of living.
ecosystem A community and its physical environment.
ecosystem services Important environmental benefits such as clean
air, clean water, and fertile soil, that the natural environment
provides.
El Niño–Southern Oscillation (ENSO) A periodic, large-scale warming of
surface waters of the tropical eastern Pacific Ocean that temporarily
alters both ocean and atmospheric circulation patterns.
endangered species A species that faces threats that may cause it to
become extinct within a short period.
endemic species Organisms that are native to or confined to a
particular region.
energy conservation Using less energy—by reducing energy use and
waste, for example.
energy efficiency Using less energy to accomplish a given task—by
using new technology, for example.
energy flow The passage of energy in a one-way direction through an
ecosystem.
enhanced greenhouse effect Additional atmospheric warming
produced as human activities increase atmospheric
concentrations of greenhouse gases.
enrichment The process by which uranium ore is refined after mining
to increase the concentration of fissionable U-235.
environmental ethics A field of applied ethics that considers the
moral basis of environmental responsibility.
environmental justice The right of every citizen to adequate
protection from environmental hazards.