STB-4.A—Explain the importance of stratospheric ozone to life on Earth

Explain the importance of stratospheric ozone to life on Earth.

• The stratospheric ozone layer is important to the evolution of life on Earth and the continued health and survival of life on Earth.
• Stratospheric ozone depletion is caused by anthropogenic factors, such as chlorofluorocarbons (CFCs), and natural factors, such as the melting of ice crystals in the atmosphere at the beginning of the Antarctic spring.
• A decrease in stratospheric ozone increases the UV rays that reach the Earth’s surface. Exposure to UV rays can lead to skin cancer and cataracts in humans.
• Enduring understanding STB-4: Local and regional human activities can have impacts at the global level.