This video gives a brief overview of the ozone hole over Antarctica. Satellite measurements provide consistent global maps of column-integrated ozone around the world, from which scientists first noticed a dramatic thinning in the 1980's. Each year an ozone hole forms at the end of winter when sunlight returns to Antarctica and reacts with manufactured chemical. Data collected by high-altitude flights over Antarctica led to the discovery that manufactured chemicals such as chloroflurocarbons, halons and bromides destroy ozone molecules.
In the satellite imagery, watch the ozone hole form at the end of winter and beginning of spring each year. Colder years experience larger holes.
In 1987 the Montreal Protocol limited the use of ozone depleting chemicals. Since then slow recovery has been observed, but these chemicals take more than 50 years to leave the atmosphere.
Scientists credit the Montreal Protocol with preventing millions of cases of skin cancer and cataracts every year and protecting wildlife and agriculture.