The ozone layer bounces back  The ozone layer bounces back The public reaction to global environmental agreements is often crickets. They can, however, pay off—big time. So confirms the latest United Nations (UN) report on the ozone layer, which comes out every four years. The thinning of the ozone layer exposes us to cancer- and cataract-causing ultraviolet rays from the sun, the result of ozone-eating chemicals that used to be common in various products, from hairsprays to refrigerators, being released into the air. Some of these chemicals also happen to be powerful greenhouse gases.  We first learned about the existence of the ozone layer in the 1930s, realized its depletion was a serious issue in the 70s, and finally did something about it on a global level in the 80s. (Those curious can watch that process unfold in this critique of the press coverage of that time.) The signing of the 1987 Montreal Protocol on Substances that Deplete the Ozone Layer set various controls on the most destructive of these chemicals, and we’ve been tracking the results of our efforts since.