Final answer:
The ozone layer protects Earth from harmful UV radiation, which is essential for life. The depletion of this layer due to CFCs has been mitigated by international efforts, showing the importance of concerted action for environmental protection.
Step-by-step explanation:
The presence of the ozone layer in the upper atmosphere is crucial for shielding the Earth from most of the Sun's harmful ultraviolet (UV) radiation.
This protection is essential because UV radiation can cause skin cancers, eye damage, and mutations in the DNA of organisms, which would be detrimental for life on Earth.
The depletion of the ozone layer due to human activities, particularly the emission of chlorofluorocarbons (CFCs), has been a significant environmental concern.
However, international agreements to phase out CFCs have led to a decrease in ozone loss and a gradual shrinking of the ozone hole over Antarctica, showcasing how global action can preserve Earth's habitability.