On average, one chlorine atom can destroy 100,000 ozone molecules. Such destructive power is tremendous when it is related to the millions of tons of CFCs that had been produced up until that time. When Rowland and Molina calculated the likely effect on the ozone layer, they could not believe their figures. They consulted another scientist Hal Johnson who confirmed their results. In 1974, Rowland and Molina published their predictions about ozone depletion in the scientific journal Nature. Although the United States was quick to ban the production of CFCs, many other countries including Britain, China, France and Japan did not. Look at the ozone depletion images from 1979-1994. These images show the amounts of ozone in the atmosphere above Antarctica in October. The colors indicate the relative amounts of ozone present. The “red” color indicates the highest amounts and the “purple” indicates the smallest amounts. In 1994, the “ozone hole” showed to have a loss of 65% of its original ozone amounts. Using the images collected on the site, describe the trends you see over time in the strength of the ozone coverage.
