Global Warming and the Greenhouse Effect

Global Warming is due to the greenhouse effect. The greenhouse effect is a naturally occurring process that aids in

heating the Earth's surface and atmosphere. It results from the fact

that certain atmospheric gases, such as carbon dioxide, water vapor,

and methane, are able to change the energy balance of the planet by

being able to absorb longwave radiation from the Earth's surface.

Without the greenhouse effect, life on this planet would probably not

exist as the average temperature of the Earth would be a chilly -18

degrees Celsius, rather than the present 15 degrees Celsius.

As energy from the sun passes through the atmosphere a number of

things take place. A portion of the energy (26 % globally) is

reflected back to space by clouds and particles. About 19 % of the

energy available is absorbed by clouds, gases (like ozone), and

particles in the atmosphere. Of the remaining 55 % of the solar energy

passing through the Earth's atmosphere, 4 % is reflected from the

surface back to space. On average about 51 % of the sun's radiation

reaches the surface. This energy is then used in number of processes

including: the heating of the ground surface; the melting of ice and

snow and the evaporation of water; and plant photosynthesis.

The heating of the ground by sunlight causes the Earth's surface to

become a radiator of energy in the longwave band (sometimes called

infrared radiation). This emission of energy is generally directed to

space. However, only a small portion of this energy actually makes it

back to space. A few naturally occurring atmospheric gases known as

the greenhouse gases absorb the majority of the outgoing infrared

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...ons of ozone gas are found

in two different regions of the Earth's atmosphere. The majority of

the ozone (about 97 %) found in the atmosphere is concentrated in the

stratosphere at an altitude of 15 to 55 kilometers above the Earth's

surface. In recent years, the concentration of the stratospheric ozone

has been decreasing because of the build-up of chlorofluorocarbons in

the atmosphere. Since the late 1970s, scientists have discovered that

total column ozone amounts over Antarctica in the springtime have

decreased by as much as 70 %. Satellite measurements have indicated

that the zone from 65 degrees North to 65 degrees South latitude has

had a 3 % decrease in stratospheric ozone since 1978. Ozone is also

highly concentrated at the Earth's surface. Most of this ozone is

created as a by-product of photochemical smog.