Ozone Layer

We’ve heard so much in the past few decades about the ozone layer in the upper atmosphere and its possible demise. Yet ozone is only a minor greenhouse gas, far behind carbon dioxide, HOH vapor, and methane in overall importance. So why is there all this fuss over the ozone layer?

Answer

Ozone plays two important roles with regard to the energy balance for Earth. As a minor greenhouse gas in all parts of the atmosphere, including near the surface, ozone helps maintain Earth’s average temperature at about 13°C instead of a frigid –17°C. The concentration of ozone in the upper atmosphere, however, regulates the UV intensity in sunlight reaching the surface. All organisms need some UV light to maintain a healthy existence, but any reduction of ozone in the upper atmosphere might allow dangerously large amounts of UV to reach the surface.

The two polar regions are extremely susceptible to ozone depletion, particularly by chlorofluorocarbon (CFC) molecules and others, because the ice crystals in the air provide these fluorocarbons with platforms for rapid ozone dissociation. Already, as a result of ozone depletions in the upper atmosphere above the polar regions, particularly above the South Polar region, there has been an increase in eye problems in land animals such as sheep in the southern parts of South America and in Australia and New Zealand.