Heat energy obtained from the hot areas under the surface of the earth.

Increase in the average temperature of the earth's surface.

A gravitational field due to a body is a region in space in which another body placed in the region experiences a force of attraction by the first body.

 A turning or growth movement by a plant or fungus in response to gravity.

Gases such as carbon dioxide and methane that trap heat in the atmosphere. These gases are emitted from a variety of natural sources like forest fires, and human sources like the combustion of gasoline and natural gas.