EART
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DDT has been linked to thinning eggshells
and population decline in some bird
species, including peregrine falcons
such as the one shown at left.
ENT
H
uman beings have seen the
planet from space only for a
few decades. Images and
studies have driven home the
realization that Earth, although it
may seem vast and rich with
resources, is in reality a small and
fragile planet.
The biosphere, the realm of
living things, is just a thin layer on
the surface of Earth but is of
particular interest to Earth system
scientists. Among the new ways of
looking at Earth is the Gaia
hypothesis, proposed by Lynn
Margulis and James E. Lovelock in
the 1970s. It suggests that living
things not only have a greater
impact on the evolution of Earth
than previously thought, but also
cooperate to maintain the Earth
system. Like Silent Spring, the
Gaia hypothesis has met with
controversy. Changes in science do
not come easily, and full acceptance
M
chemical DDT, had unforeseen
effects on other life forms. DDT
killed not only the crop-destroying
insects, but birds and fish as well.
Once it entered the environment,
DDT spread its toxins throughout
the food chain.
With her book’s publication,
Carson found herself at the center
of a storm of controversy. The
pesticide industry dismissed her
scientific evidence. Despite the
opposition, Silent Spring became an
influential book, leading to a ban on
DDT in the United States. Carson
is often called the
founder of today’s
ecology movement.
Rachel Carson’s
life shows that
one person can
make a difference.
What can you do to
make a difference for
yourself, for others,
for the environment?
VIR
S EN ON
H’
of Earth system science may be
years away, even though, around
the world, organizations such as
NASA have embraced this new way
of looking at Earth.
At times it is difficult for people
to see beyond their immediate
needs and consider the future. You
may have done this yourself; it’s a
very human thing to do. Growing
environmental crises, however,
make it plain that we can no longer
live this way. Native American
philosophy urges that with every
decision made or action taken, we
consider its impact on the lives of
those seven generations from now.
Would you say that decision makers
today follow that philosophy?
CLASSZONE.COM
How Can Getting Farther
Away from Earth Help Us See
It More Clearly? Instruments on
orbiting satellites collect an
incredible array of information
about our planet every day.
Explore how sensors gather
information such as the amount
of water vapor in the air or the
shape of the sea floor. Plan to view
Earth from a specific satellite.
Make a prediction about what you
might see.
Keycode: ESU101
63