Your impact on the Earth varies depending on where you live Some countries make more demands on the environment The United States for example is home to 5 percent of the world’s population but it uses 25 percent of the world’s resources The United States has an ecological footprint larger than any other nation Much of this footprint is attributed to life in the big city Cities have higher levels of air pollution from cars and factories than rural areas The state of California has the unfortunate distinction of being home to many of the most polluted cities Los Angeles California is the most polluted city in America 6
CHAPTER TWO Fossil Fuels Affect the Environment Before the industrial revolution our impact on the planet was fairly small But in the mid-1700s people began replacing human workers with machines Where people had once relied on wind water and wood for their energy needs they now powered their machines with the fossil fuels coal oil and natural gas Power plants that burn coal produce more harmful carbon dioxide than all cars trucks planes and other forms of transportation combined 8
Oil rigs such as this one in the Gulf of Mexico drill natural gas and oil from far beneath the sea floor 9
