|
|
Post by marchesarosa on Sept 10, 2010 9:08:02 GMT 1
Was the ozone hole "healed" or is it simply a permanent feature of our atmosphere that was "discovered" a few decades ago (like America was "discovered" by Columbus)?
I seem to remember the banning of CFCs was hailed as a success story. But was it? Why do we hear nothing about the "ozone hole" any more except, apparently, to plug gaps in the understanding of southern hemisphere climate?
Some people point to anti-CFC legislation as a precursor of what anti-CO2 legislation could achieve.
Is this a correct analogy?
Has the production of CFCs from all sources - natural and man-made - actually fallen?
Sorry for all the questions. I have often wondered about this.
|
|
|
|
Post by rsmith7 on Sept 10, 2010 9:15:28 GMT 1
I don't think it was even a "hole"; didn't they just say it had "thinned"? Considering it's only 5mm thick in any case, the story begins to look like another eco-propaganda scare story. Maybe I'm just becoming (justifiably) cynical. Minus 9 marchessa? Amatuer!  |
|
|
|
Post by havelock on Sept 10, 2010 9:25:34 GMT 1
Has the production of CFCs from all sources - natural and man-made - actually fallen? I believe the production of CFCs has been banned and the disposal of existing ones is supposed to be controlled. Google the Montreal Protocol for more details. |
|
|
|
Post by havelock on Sept 10, 2010 9:39:47 GMT 1
This is a pretty good site with some interesting diagrams www.theozonehole.com/One of the figures is captioned "NASA/NOAA satellite data showing the rise in stratospheric chlorine and corresponding decline in ozone layer thickness from 1979 to 1997. As stratospheric chlorine declined in response to enactment of the Montreal Protocol, the first stage of ozone recovery began." which sounds like good news. It seems that this may be a case of man noticing the damage he was doing and then doing something to prevent further damage and to repair the damage that has been done. A good news story  |
|
|
|
Post by havelock on Sept 10, 2010 10:03:00 GMT 1
Considering it's only 5mm thick in any case, Not sure if your're referring to the ozone layer or the ozone hole here. The former is tens of kilometres thick. The latter varies and is a reference to the reduction of concentration of ozone in the ozone layer - so again could be said to be tens of kilometres thick. |
|
|
|
Post by rsmith7 on Sept 10, 2010 10:49:11 GMT 1
|
|
|
|
Post by rsmith7 on Sept 10, 2010 10:56:44 GMT 1
"Scientists use a unit called the Dobson Unit (abbreviated DU) to describe the amount of ozone in the atmosphere. They calculate how thick the ozone layer would be if all ozone in the atmosphere were compressed into a single layer at zero degrees Celsius and sea level atmospheric pressure (that is 1013 mbar). To get a better understanding, picture a column extending through the ozone layer. That column would capture a certain number of ozone molecules. However, these ozone molecules would be widely spread out throughout the column. Now let’s say that you were to take all the ozone molecules caught within the column and compress them to sea level pressure, and then measure the thickness in millimeters. Multiply the number by 100, and you have the thickness of the ozone layer expressed in Dobson Units! The average thickness is about 300 DU, which equals a three millimeter (or 0.12") thick layer of compressed ozone. Yes, the ozone layer is really rather thin!" www.biospherical.com/nsf/student/page1.htmlThe plot thickens! So the ozone layer isn't a layer at all - it's a trace gas like co2. So the pitiful amount of ozone in the upper atmosphere was found to be what in the purported "hole"? Diminished?... or Gone? I smell a rat. |
|
|
|
Post by havelock on Sept 10, 2010 11:03:44 GMT 1
|
|
|
|
Post by marchesarosa on Sept 10, 2010 11:04:47 GMT 1
I repeat
"Has the production of CFC (edit) "equivalents" from ALL sources - natural and man-made - actually fallen? "
I understand there are natural volcanic sources of CFC - type compounds).
|
|
|
|
Post by havelock on Sept 10, 2010 11:10:35 GMT 1
|
|
|
|
Post by marchesarosa on Sept 10, 2010 11:50:02 GMT 1
"MAJOR volcanic eruptions... can in principle inject HCl directly into the middle stratosphere." "An eruption with VEI>5 can send a plume up to 25km, in the middle of the ozone layer. Such eruptions occur about once a decade". stason.org/TULARC/science-engineering/ozone-depletion-stratospheric-chlorine/23-Volcanoes-put-more-chlorine-into-the-stratosphere-than-CF.htmlOther volcanically produced compounds have the same or even greater effect on ozone depletion as CFCs, don't they? There are in fact MANY sources of compounds on earth which affect atmospheric ozone breakdown. Some of them are discussed here "Volcanic Halocarbons: Chlorofluorocarbons (CFCs) in Volcanic Emissions" Are we sure we really have a handle on all the NATURAL sources of variation in the atmosphere? Seems to me congratulating ourselves about having healed the ozone hole by reducing anthropogenic CFCs is a bit premature. It leads to the mindset that believes limitation of another scary atmospheric compound - CO2 - can produce similar benefits. CFCs cannot be claimed to be the major source of impact on the ozone layer - there are much greater natural sources of compounds that do the same thing. The myth of healing the ozone hole via CFC reduction is probably an unsuitable model of a "successful" atmospheric intervention on which to base CO2 limitation. cfc.geologist-1011.net/ |
|
|
|
Post by havelock on Sept 10, 2010 12:14:23 GMT 1
CFCs cannot be claimed to be the major source of impact on the ozone layer - there are much greater natural sources of compounds that do the same thing. Good grief - quick, give that woman a Nobel Prize, she clearly deserves it for her contribution to science and the environment. Where can I pick up a copy of the work that you have published to demonstrate this?  |
|
|
|
Post by marchesarosa on Sept 10, 2010 12:36:07 GMT 1
So did the banning of CFCs "heal the ozone hole"? Or did the media just lose interest when a more juicy scare story in the form of CO2 came along?
|
|
|
|
Post by rsmith7 on Sept 10, 2010 12:37:40 GMT 1
Was there ever a hole? Even half a hole?  |
|
|
|
Post by marchesarosa on Sept 10, 2010 12:40:22 GMT 1
This where I read about it, Havelock. cfc.geologist-1011.net/ It looks well referenced. Is it wrong? I was not out of order, surely, in questioning why the last big "environmental" scare story prior to AGW had dropped from the public consciousness? Is the ozone hole still there? Is it "dangerous"? |
|
