Chapter 2, Section 4
(Pages 63–66)
Human-Environment
Interaction
All living things are dependent upon one another and their surroundings
for survival. As you read, complete this chart by identifying four environmental problems and what people are doing to solve them.
Problem
Solution
The Atmosphere
1.
2.
3.
4.
5.
People burn oil, coal, and gas for electricity, to power factories, and to move cars. Unfortunately, burning oil, coal, and gas
causes air pollution.
Air Pollution
Air pollution can lead to smog. Smog is a thick haze of
smoke and chemicals. People may have breathing problems
when smog settles above cities.
Chemicals in air pollution can combine with precipitation
to form acid rain. Acid rain kills fish, eats away at the surfaces
of buildings, and destroys trees and other plant life.
Ozone is found in the atmosphere. It provides a shield
against damaging rays from the sun. Some human-made chemicals destroy the ozone layer. This may result in more humans
getting skin cancer.
The Greenhouse Effect
The greenhouse effect occurs when gases in the atmosphere
trap the sun’s heat. Because this heat is trapped, Earth remains
warm, allowing living things to survive. Without the greenhouse
effect, Earth would be too cold for most life-forms.
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Chapter 2, Section 4
Copyright © by The McGraw-Hill Companies, Inc.
As you read, list five
negative effects of
air pollution.
(page 64)
The Atmosphere
How is the greenhouse effect positive
and negative?
Some scientists believe air pollution strengthens the greenhouse effect. They claim that the burning of coal, oil, and natural gas traps the sun’s heat near the Earth’s surface and raises
the planet’s overall temperature. Such global warming could
cause climate changes, melt polar ice, and result in flooding
of coastal areas.
Many nations are trying to reduce global warming. Their
focus is on using oil and coal more efficiently and cleanly. They
also are looking at forms of energy that do not pollute. These
include wind and solar power.
The Lithosphere
Copyright © by The McGraw-Hill Companies, Inc.
Write down the main
idea of the passage.
(continued)
(page 65)
The Earth’s crust is also known as the lithosphere. It
includes all land above and below the oceans. Activities such
as farming and cutting down trees can harm the lithosphere.
Topsoil is an important part of the lithosphere. It can be
carried away by wind or water. Farming also puts topsoil at risk.
However, farmers can limit the loss of topsoil in several ways.
Instead of plowing straight rows, they can plow along the
curves of the land. This is called contour plowing. Farmers also
use crop rotation, which means they rotate or change what is
planted from year to year. In addition, farmers plant grasses in
fields without crops. The grasses hold the topsoil in place.
Another danger to topsoil is deforestation, or cutting down
forests without replanting them. Tree roots hold soil in place.
When trees are cut, the topsoil may be eroded. Trees are important for other reasons too. They support the water cycle and
replace oxygen in the atmosphere. Forests are also home to
many plants and animals.
The Hydrosphere and Biosphere
Define the biosphere
and the hydrosphere.
Chapter 2, Section 4
(page 66)
Surface water and groundwater make up the Earth’s hydrosphere. Water is necessary for human life, but the amount of
freshwater is limited. Therefore, people should practice conservation. This means resources such as water should be used
carefully so they are not wasted.
Irrigation is a way farmers collect water and then use it on
their crops. Irrigation often wastes water. Much of the water evaporates or soaks into the ground before it even gets to the crops.
17
The Hydrosphere and Biosphere
(continued)
Pollution harms the hydrosphere. Pesticides are chemicals
that farmers use to kill insects. Strong pesticides and other
chemicals sometimes spill into clean water. Then the water
supply is threatened.
The biosphere is the “living” part of the planet—all the
plants and animals. The biosphere is divided into many ecosystems. An ecosystem is a particular environment shared by
certain plants and animals that need one another to survive.
Earth’s biodiversity, or the variety of plants and animals,
is getting smaller. Human activities have led to fewer types
of plants and animals in some ecosystems.
Wrap -Up
Answer these questions to check your understanding of the entire
section.
1. Identifying What human activities contribute to global warming?
2. Determining Cause and Effect How does contour plowing prevent the
loss of topsoil?
18
Chapter 2, Section 4
Copyright © by The McGraw-Hill Companies, Inc.
an outline for a presentation about the ways in which the
I nformative Create
hydrosphere is threatened.