Human activities, such as reducing the amount of forest cover, increasing the amount and variety of chemicals released into the atmosphere, and intensive farming, have changed the earth's land, oceans, and atmosphere. Some of these changes have decreased the capacity of the environment to support some life forms. The environment may contain dangerous levels of substances that are harmful to human beings. Therefore, the good health of individuals requires monitoring the soil, air, and water and taking steps to keep them safe. At present, all fuels have advantages and disadvantages so that society must consider the trade-offs among them.
Industrialization brings an increased demand for and use of energy.
Such usage contributes to the high standard of living in the industrially developing nations, but also leads to more rapid depletion of the earth's energy resources and to environmental risks associated with the use of fossil and nuclear fuels. Graphs can show a variety of possible relationships between two variables. The graphic display of numbers may help to show patterns such as trends, varying rates of change, gaps, or clusters. Such patterns sometimes can be used to make predictions about the phenomena being graphed. Sometimes people invent a general rule to explain how something works by summarizing observations.