Though rare, we do get the occasional story offering up something other than differing shades of doom and gloom on climate science. Case in point: according to a new study, the levels of hydrogen chloride (HCl) in the atmosphere - one of the chemicals identified as being most harmful to the Earth's ozone layer (alongside chlorofluorocarbons) - have been steadily declining over the past few years after reaching a peak in the early 1990s. HCl is typically spewed from volcanoes or emitted when chemicals used to make various materials - including rubber and plastics - are broken down.
Lloyd Wallace and William Livingston, two Arizona-based astronomers, tracked HCl concentrations over the last 35 years and found that levels of the noxious chemical fell by an average of about 1.8% per year since 1993 - a great improvement over the average annual increase of 5.7% registered from 1971 to 1993. This is great news, says Christopher Cantrell, an atmospheric chemist at the National Center for Atmospheric Research in Boulder, CO: "... there is indeed good evidence that the chlorine loading in the atmosphere is going down as a result of the Montreal Protocol,"It's too bad their analysis doesn't tell the whole picture, however. According to Cantrell, their observations glossed over the levels of bromine, a much rarer element in the atmosphere that is "much more effective at destroying ozone." Still, he remains optimistic about the ozone layer's future well-being though he cautions that it won't be a speedy recovery: "I think most everyone agrees that we should see [full ozone layer] recovery eventually."
Via ::ScienceNOW: More Good News for the Ozone Layer (news website)