Digressing here, but the ozone hole over the antarctic was always going to take time to recover because of the approximately 50 year residence time of the CFCs in the upper atmosphere. Cold temperatures can actually speed up depletion because of certain ice crystal formations that give a boost in the CFC+sunlight+O3 reaction rate. Note that it doesn't mean that 50 years are needed to get rid of all CFCs in the atmosphere, it is just a measure of the amount of time it is expected to take for half of the gas that is already there to be removed. That doesn't account for the amount of time it has taken for CFC usage to drop in the first place, and the fact that there are still CFC pollution occurring (albeit far less than in the 80's).
Ben Root
Out of curiosity, has the ice crystal acceleration been established in the lab? I recall it being proposed to help save the models, but that was a long time ago. IIRC, another reaction rate was remeasured in 2005 and found to be 10X lower than thought, but don't recall which one. I've been looking for a good recent review article to see what the current status is. The funding mostly disappeared after 1994 along with several careers. Freon is still used -- off the books -- in several countries, a phenomenon now seen with increasing coal generation.
ChuckÂ