The atmosphere has constantly changed through geologic time. Chemical reactions using gases have always occurred. Organisms seem to evolve their structure to the atmosphere. Every organism on Earth interplays with these ever-changing environments.

For instance, humans have changed their atmosphere in the short time we have been on Earth. As we discovered fire and created a use for different forms of energy we also change our atmosphere. As we discharge substances into the atmosphere, we can change its vertical structure, which may cause harm later on.

One of the concerns of our atmosphere today is the deterioration of the ozone layer which protects us from excessive ultraviolet radiation. There is a thinning of ozone over Antarctica that occurs each Antarctic spring. Up to 70% of the ozone normally found over Antarctica is destroyed. Some of the reasons for this depletion are complex. Evidence that human activities affect the ozone layer has been building up over the last 20 years, ever since scientists first suggested that the release of chlorofluorocarbons (CFCs) into the atmosphere could reduce the amount of ozone over our heads. But could it be other factors? How we affect it and to what degree is still being monitored and researched.

Ozone thinning in the Antarctic