>Walter,
>
>With all due respect, I think the one not understanding the issue is you, and while I am no expert and I fully recognize my ignorance and I am slow to understand things, it takes more than a couple of veilled accusations to make me change my mind, call me stubborn.
>
>First of all, you completely ignore the first part of my answer, so let me bring it back to you, for I think is very relevant:
>
>>>It was said in the 90-ties that hole in the ozon layer would eventually grow to span the whole earth and it would be catastrophic for the rest of the world. As always with these things, there are multiple factors involved. CFC's are one factor, but the extremely cold nature and vortex winds on the antartic another. That is the reason why it occurs mainly there.
>
>>You say it as if there were not actions taken to remediate the issue i.e. the Montreal Protocol.
>
>You seem to believe that there was never an issue with the ozone layer that was nothing more than a natural cycle due to some "vortex winds" and "extemerly cold" temperatures and CFC is just one factor. First of all "vortex winds" and "extremely cold" temperature by themselves would NOT affect the ozone layer at all, the interaction of those elements with man made CFC is the problem (enphasis in man made CFC). Without the Montreal Protocol (although there were already steps by some governments in that direction) the production of it might not have been phased out and then the doomsday prediction might have been just doomsday, but you seem to believe that it was just some collective histeria that time proved wrong.

No, I never denied that there is a human component to it. But it is like it says one component of several, see below.

>I would also recommend you some read, for example from a link that says:

>"While the Montreal Protocol may have averted disaster, the ozone layer remains in flux, and will stay in the sights of atmosphere-observing satellites for a long time."
>
>Secondly, that link that you provided is very confusing for a simple mind like mine, it starts saying "Cold temperatures, chlorine and a stagnant atmosphere caused a thinning in the ozone layer...This ozone loss is not the more famous ozone hole"... I think you lost me there, that is exaclty what the ozone hole is all about, or where does the chlorine come from? I do not know, I think I missed your point completely with this, if you made me read it for it says: "which has been shrinking since the phase-out of chlorofluorocarbons, or CFCs" or what is says in the section "Future outlook" then it validates what I was saying about the Montreal Protocol...

I never said the montreal protocol is not of any influence. That is not the point.
The point is the predicting the doomsday scenarios by climate activists which is exaggerated in many ways because:

- The 'hole' in the ozon layer only occurs under certain condition that as the article implies. Very cold winds and a cutting off supply of ozon from the equator are factors that contribute to the growing an shrinking of the hole
- The hole, isn't exactly a hole, but is defined as when the concentration of ozon fall below a certain threshold.
- The hole, is on its biggest in spring as it comes out of winter, but shrinks again for the rest of the year. This has nothing to do with CFCs concentration, but because of the cold climate and vortex winds on the antartic.

Just the lack of the nuance, at least up here in Europe, communicating with the public threw me off.

>>Data = the measurements
>>Information = the size 2011 hole in the ozon layer is bigger than the year before that.
>>Knowledge = that the sizes are growing and shrinking through time
>
>WTH? Well, you are ignoring the fact that the direct cause of the growing and shrinking of the ozone hole is the levels of chlorine in the atmosphere and the weather (cold + wind), not just "time" that suggest is all natural...

That is false, the concentration of CFCs has been on a steady decline and you pointed out 2011 as a year that marked the end of the decline. That is not true because there are other factors contributing to shrinking and of the ozon hole: The cold and winds. This was the cause of bump in the trend of a smaller ozon layer. The data of 2012 - 2014 indicate that the trend is continuing.

One other thing that is poorly documented and quantified about ozon depletion is the set of natural causes. Because of the focus on CFCs (and rightly so), there hasn't been a lot of research into natural causes of ozon depletion. Chlorines is a molecule that also has a natural form and also destroys ozon, though it is believed it only accounts for a small percentage of ozon depletion. Also some scientist believe that volcanic eruptions do have some influence on it as well. See http://earthobservatory.nasa.gov/Features/WorldOfChange/ozone.php


But we are drifting off in too much detail.

Summary
- Year to year variations in the size of the hole of the ozon layer are mainly natural + a slow downward trend because of the banning of CFCs.
- You can't draw any conclusions on individual measurements. As shown the 2011 case had an unusual natural cause, not a man made one. Even if we had no man made CFCs in history, 2011 would have show a much thinner layer than previous years.
- We only are recording ozon layers data from satelites since 1979. Only 36 years. We have no reliable records of variability before that point. Don't you think that is a bit short to have a good understanding about the history and future of our ozon layer?

Walter,