What is the Ozone Layer?
The ozone layer is a region of Earth's stratosphere that absorbs most of the Sun's harmful ultraviolet (UV) radiation. It is primarily composed of ozone (O3), a molecule made of three oxygen atoms, which forms naturally when UV radiation splits oxygen molecules (O2) into individual oxygen atoms, allowing them to recombine with other O2 molecules.
Composition and Formation in the Stratosphere
Located roughly 10 to 50 kilometers (6 to 31 miles) above Earth's surface, with the highest concentration at about 20-30 kilometers, the ozone layer acts as a natural sunscreen. The formation process is continuous: solar UV radiation breaks apart O2 molecules into single oxygen atoms (O). These highly reactive single atoms then collide with other O2 molecules to form O3 (ozone), a process that balances ozone destruction and creation in the stratosphere.
Why the Ozone Layer is Crucial for Life
The ozone layer's most vital role is to shield life on Earth from the most damaging types of UV radiation: UV-B and UV-C. Without this protective barrier, these high-energy rays would reach the surface, leading to severe health issues in humans like skin cancer, cataracts, and immune system suppression. It also safeguards ecosystems by preventing damage to plant growth, aquatic life, and essential microorganisms.
Threats and Global Conservation Efforts
Human-made chemicals, particularly chlorofluorocarbons (CFCs) and other ozone-depleting substances (ODS), were found to significantly deplete the ozone layer, creating an 'ozone hole' over Antarctica. In response, the international community adopted the Montreal Protocol in 1987, an agreement that phased out the production of these harmful chemicals, leading to a slow but steady recovery of the ozone layer, demonstrating successful global environmental cooperation.