On Tue, Nov 24, 2020 at 12:28 PM Benjamin Root <ben.v.r...@gmail.com> wrote:
> 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. Chuck
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