cancer. We can’t state with absolute certainty which
smokers will be diagnosed with lung cancer, but this
uncertainty does not mean that there is no correlation
between smoking and lung cancer. On the basis of the
available evidence, we say that people who smoke have an
increased risk of developing lung cancer.
In conclusion, the aim of science is to increase hu-
man comprehension by explaining the processes and
events of nature. Scientists work under the assumption
that all phenomena in the natural world have natural
causes, and they formulate theories to explain these phe-
nomena. The process of science as a human endeavor
has shaped the world we live in and transformed our
views of the universe and how it works.- What is environmental science? What are some
of the disciplines involved in environmental
science? - What are the five steps of the scientific
method? Why is each important?
book, the word theory is always used in its scientific sense,
to refer to a broadly conceived, logically coherent, and
well-supported explanation.
Unfortunately, many questions that are most impor-
tant to environmental scientists cannot be formulated as
testable hypotheses. For example, we cannot design an
experiment to test the hypothesis that if we double the
carbon dioxide concentration of the atmosphere, global
average temperatures will increase. Consequently, much
of environmental science requires that we apply our best
understanding of theory and data to arrive at conclusions
about what we expect will happen.
Despite the fact that theories are generally accepted,
there is no absolute truth in science, only varying degrees
of uncertainty. Science is continually evolving as new evi-
dence comes to light, and therefore its conclusions are al-
ways provisional or uncertain. It is always possible that the
results of a future experiment will contradict a prevailing
theory and show at least one aspect of it to be false.
Uncertainty, however, does not mean that s cientific
conclusions are invalid. For example, overwhelming
evidence links cigarette smoking and incidence of lung
How We Handle Environmental Problems
LEARNING OBJECTIVES
- List and briefly describe the five stages of
solving environmental problems.
B
efore examining the environmental prob-
lems discussed in the remaining chapters of
this book, let’s consider the elements that
contribute to solving those problems. How,
for example, can we handle water pollution in a river
(Figure 1.11)? At what point are conclusions regarded
as certain enough to warrant action? Who makes the de-
cisions, and what are the trade-offs? Viewed simply, there
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This pollution control officer is measuring the oxygen level in the
Severn River near Shrewsbury, England. When dissolved oxygen
levels are high, pollution levels (of sewage, fertilizer, and such)
are low. Ben Osborne/Stone/Getty Images
20 CHAPTER 1 The Environmental Challenges We Face