Ozone layer

Definition

The ozone layer is a region of Earth's stratosphere that contains a high concentration of ozone (O₃) molecules, which absorb the majority of the sun's harmful ultraviolet (UV) radiation. This layer is crucial for protecting living organisms from excessive UV exposure, which can lead to skin cancer, cataracts, and other harmful effects. The ozone layer is primarily located between about 10 to 30 miles above the Earth's surface, and its depletion has significant environmental implications.

5 Must Know Facts For Your Next Test

1. The ozone layer absorbs about 97% to 99% of the sun's harmful UV radiation, significantly reducing the amount that reaches Earth's surface.
2. Ozone is created when UV light splits oxygen molecules (O₂) into individual atoms, which then react with other O₂ molecules to form ozone (O₃).
3. Human activities, particularly the use of CFCs and other ozone-depleting substances, have led to significant thinning of the ozone layer since the mid-20th century.
4. The Montreal Protocol, an international treaty signed in 1987, has been effective in phasing out many substances responsible for ozone depletion.
5. While recovery of the ozone layer is underway due to global efforts to reduce CFC emissions, full recovery is not expected until around 2060 or later.

Review Questions

• How does the presence of the ozone layer influence life on Earth?
  • The ozone layer plays a critical role in supporting life on Earth by absorbing the majority of harmful ultraviolet (UV) radiation from the sun. Without this protective barrier, increased UV exposure could lead to higher rates of skin cancer and cataracts in humans, as well as detrimental effects on ecosystems and wildlife. By filtering out these harmful rays, the ozone layer helps maintain a stable environment conducive to life.
• Discuss the impacts of human activity on the ozone layer and what steps have been taken to mitigate this issue.
  • Human activities, especially the release of chlorofluorocarbons (CFCs) and other ozone-depleting substances, have significantly contributed to the thinning of the ozone layer. These compounds break down ozone molecules when they are released into the atmosphere. In response, global efforts such as the Montreal Protocol have been implemented to phase out these harmful substances. This international treaty has successfully reduced CFC emissions, contributing to signs of recovery in the ozone layer.
• Evaluate the long-term implications of ozone layer recovery for environmental health and climate stability.
  • The recovery of the ozone layer has significant long-term implications for environmental health and climate stability. As the ozone layer heals from past damage due to reduced levels of CFCs and other harmful substances, it will continue to provide protection against excessive UV radiation. This not only benefits human health by lowering skin cancer rates but also supports ecosystem resilience by preserving plant and animal species sensitive to UV exposure. Furthermore, understanding and maintaining the balance of atmospheric layers will be crucial in addressing broader climate challenges and promoting sustainable practices.

Related terms

Ultraviolet Radiation: A type of electromagnetic radiation emitted by the sun that can be harmful to living organisms and is partially absorbed by the ozone layer.

Stratosphere:

The second layer of Earth's atmosphere, located above the troposphere, where the ozone layer is situated and where temperature increases with altitude due to ozone absorption of UV radiation.

Chlorofluorocarbons (CFCs): Man-made chemical compounds that contribute to ozone depletion when released into the atmosphere, leading to thinning of the ozone layer.