Environment.

Rain that contains more acid than normal.

A slide of a large mass of dirt and rock down a mountain or cliff.

The removal of trees faster than forests can replace themselves.

Air pollution by a mixture of smoke and fog.

The shaking that results from the movement of rock beneath Earth's surface.

The number of a people in an area exceeds the capacity of the environment to support life at a decent standard of living.

A tropical forest, usually of tall, densely growing, broad-leaved evergreen trees in an area of high annual rainfall.

Disappearance of a species from all parts of its geographical range.

An extreme shortage of food.

A rapidly spreading and usually fatal disease.

A long period of dry weather.

The process by which fertile land becomes desert,typically as a result of drought, deforestation, or agriculture.

Natural situation in which heat is retained in Earth's atmosphere by carbon dioxide, methane, water vapor, and other gases.