In what should be a precautionary tale to the 'global warming' crowd, the ozone hole is not healing the way it was supposed to. According to NASA,
Scientists around the world are looking for evidence that the ozone layer is beginning to heal, but this year’s data from Antarctica do not hint at a turnaround.
The Montreal Protocol went into effect in 1989, twenty-two years ago. It banned a number of chemicals believed to play a major role in depleting the earth's stratospheric layer of protective ozone. The theory was that the ozone hole would heal as the chemicals gradually made their way out of the atmosphere. So far, that has not occurred.
Levels of most ozone-depleting chemicals in the atmosphere have been gradually declining since an international treaty to protect the ozone layer, the 1987 Montreal Protocol, was signed. That international treaty caused the phase out of ozone-depleting chemicals, then used widely in refrigeration, as solvents and in aerosol spray cans.
So, 22 years later and with chemical levels down, we still got the 9th largest ozone hole in history. NASA seems surprised; I'm not. In 2007, the Nobel Prize for Chemistry was awarded to Gerhard Ertl for his work on chemical processes on solids. His work seems to indicate that the chemical process behind the ozone depletion isn't what science believed in 1979, which may be the reason the hole is not healing at the expected rate.
Ozone chemistry -- at least in theory -- is simpler than the process through which weather occurs. If the science behind ozone depletion is more complicated than we thought, it seems to me that the "science is settled" mantra surrounding global warming rings even less true.