Sean Callery - Secrets of Pollution and Conservation

ANDREW SOLWAY

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Library of Congress Cataloging-in-Publication Data

Solway, Andrew.
Secrets of pollution and conservation / Andrew Solway.
p. cm. -- (Science secrets)
Includes bibliographical references and index.
1. Pollution--Juvenile literature. 2. Conservation of natural
resources--Juvenile literature. I. Title.
TD176.S6423 2011
363.73--dc22

2010003943

1 3 6 5 4 2

People have been living on Earth for about 200,000 years. For most of that time, the world population was less than a million people. However about 10,000 years ago, the population began to grow.

By the 1800s, the world population was more than one billion. People in Europe and North America began to make steel and steam engines.

Steam engines helped build bridges, railways, and ships, but they also caused pollution. These machines released smoke and harmful gases into the air.

Trees being cut down in a rain forest in Sumatra. Felled forests take decades to recover.

Mammoths disappeared about 10,000 years ago. The main cause was probably human hunting.

The pollution of the air continued into the twentieth century as cars choked the roads and airplanes filled the skies. Meantime, by 1999, the human population topped six billion.

NOTHING NEW

Humans were causing damage to the environment well before the Industrial Revolution. Scientists think that hunting by humans as long as 45,000 years ago may have led to the extinction of mammoths, saber-toothed tigers, and other large animals.

In this book, you will see how human activities are using up resources and damaging the earth. You will also discover what steps people are taking to restore the natural environment.

WORLD POPULATION GROWTH (BILLIONS OF PEOPLE)

The world population has taken thousands of years to reach three billion, but it has doubled to six billion in just forty years.

Burning fossil fuels is one of the main ways that we get energy. We burn fuel to heat our homes, to drive cars, and to produce electricity in power plants.

However, burning fossil fuel is the main source of air pollution around the world. It releases more smoke and gases into the air than any other human activity.