SpaceAdmiral writes "Since the implementation of the Montreal Protocol, which limited ozone-destroying gasses like CFCs, the Earth's ozone layer has been recovering. However, new studies show that the ozone in the lower stratosphere is actually recovering faster than the Montreal Protocol alone can explain." From the article: "It's a complicated question. CFCs are not the only things that can influence the ozone layer; sunspots, volcanoes and weather also play a role. Ultraviolet rays from sunspots boost the ozone layer, while sulfurous gases emitted by some volcanoes can weaken it. Cold air in the stratosphere can either weaken or boost the ozone layer, depending on altitude and latitude. These processes and others are laid out in a review just published in the May 4th issue of Nature: 'The search for signs of recovery of the ozone layer' by Elizabeth Westhead and Signe Andersen."