¥Atmospheric Composition - Anything that
changes the radiative
properties of the atmosphere (volcanic aerosols,
carbon dioxide).
¥Astronomical - Anything that alters the
amount or distribution
of solar energy intercepted by the Earth (solar
variations, orbital variations).
¥EarthÕs Surface - Anything that alters
the flow of energy at
the Earth's surface or changes its distribution (desertification,
continental drift).