Index Home About Blog
From: rparson@spot.Colorado.EDU (Robert Parson)
Newsgroups: sci.chem
Subject: Re: The Greenhouse Effect - Counterargument
Date: 9 May 1997 23:42:12 GMT

In article <>, Mike Wooding  <> wrote:

> All of which suggest that very, very little water gets into
> the stratosphere ... but some does. And some Chlorine, too?

 Sure, some. The World Meteorological Organization 1994 Scientific
 Assessment estimates the sources of stratospheric chlorine as:

 CFC-12:  28%
 CFC-11:  23%
 CH3Cl:   15%
 CCl4:    12%
 CH3CCl3: 10%
 CFC-113:  6%
 HCFC-22:  3%
 HCl:      3%

 HCl and CH3Cl are primarily natural, the rest are almost entirely
 anthropogenic. So about 20% of the chlorine now in the stratosphere
 had a natural origin.

 The executive summary of the Assessment is available through the
 NOAA Aeronomy Lab's web page: :

Subject: Re: Ozone Depletion
From: rparson@spot.Colorado.EDU (Robert Parson)
Date: Nov 08 1996
Newsgroups: sci.chem

A few good web sites:

Gregory Dubois-Felsmann's SOLIS page at NCAR:
The NOAA Aeronomy Lab:

The British Antarctic Survey:

The Consortium for International Earth Science Information Network:

The Centre for Antarctic Information and Research (ICAIR) in New Zealand: 

The TOMS home page:

The EASOE home page:

The UARS Project Definition page:

The HALOE home page:

The Institute for Meteorology at the Free University of Berlin:

The Climate Prediction Center's TOVS Total Ozone Analysis page:

The USDA UV-B Radiation Monitoring Program Climate Network,

Books and Survey Articles, Introductory Accounts:

 R. R. Garcia, "Causes of Ozone Depletion", _Physics World_
 April 1994 pp 49-55.

 T. E. Graedel and P. J. Crutzen, 
 _Atmospheric Change: an Earth System Perspective_, Freeman, NY 1993.

 F.S. Rowland, "Chlorofluorocarbons and the depletion of 
 stratospheric ozone", _American Scientist_ _77_, 36, 1989.

 F. S. Rowland and M. J. Molina, "Ozone depletion: 20 years after the
 alarm", _Chemical and Engineering News_, 15 Aug. 1994, pp. 8-13.

 P. S. Zurer, "Ozone Depletion's Recurring Surprises
 Challenge Atmospheric Scientists", _Chemical and Engineering News_,
 24 May 1993,  pp. 9-18.

 Books and Review Articles, more technical:

 G. Brasseur and S. Solomon, _Aeronomy of the Middle Atmosphere_,
 2nd. Edition, D. Reidel, 1986
 (They are writing a 3rd Edition but I don't know when it will be
 published. When it is, I expect it to be _the_ definitive treatise on
 the subject.)

 H. S. Johnston, "Atmospheric Ozone", _Annu. Rev. Phys. Chem._ _43_, 1, 1992.

 M. McElroy and R. Salawich,
 "Changing Composition of the Global Stratosphere", _Science_ _243, 763, 1989.

 F. S. Rowland, "Stratospheric Ozone Depletion", 
 _Ann. Rev. Phys. Chem._ _42_, 731, 1991.

 M. L. Salby and R. R. Garcia, "Dynamical Perturbations
 to the Ozone Layer", _Physics Today_ _43_, 38, March 1990.

 S. Solomon, "Progress towards a quantitative understanding
 of Antarctic ozone depletion", _Nature_ _347_, 347, 1990.

 R. P. Wayne, _Chemistry of Atmospheres_, 2nd.  Ed., Oxford, 1991.

From: (Robert Parson)
Newsgroups: sci.chem,sci.physics
Subject: Re: Kyoto and  global "Warming"
Date: 16 Jan 1998 21:08:22 GMT

In article <>,  <> wrote:
>In article <69m0f1$>, (Robert Parson) writes:
>> Well, there was no ozone hole before stratospheric Cl concentrations
>> reached ~2 ppb, up from a natural background of 0.6 ppb, and there
>> is little or no doubt that CFCs are responsible for that rise.
>Well, that's where things are not quite as conclusive, IMO.
>Measurements of stratospheric ozone over the Antarctic don't date that
>far back so "there was no ozone hole before" is a stronger statement
>than the situation warrants.  As system needs to be measured over a
>time span of quite a few intrinsic time constants before you can say
>anything like this.

 The stratosphere doesn't have much of a memory - half of its mass is
 exchanged with the troposphere in less than two years. As for
 "intrinsic time constants", the longest one known for stratospheric
 ozone is the 11 year solar cycle. Antarctic ozone measurements go
 back to 1956 (the ozone hole first appeared in 1979-85) and
 measurements at other latitudes go back much farther, to the mid-1920s
 in some cases.

 But that is somewhat aside from the point, because the evidence that
 CFCs caused the ozone hole is not primarily in the historical record
 (though that record has played a crucial role in establishing the
 foundations of the science) but rather in the present day stratosphere.
 The argument goes like this: consider those mechanisms that are
 known to influence stratospheric ozone. These include overall solar
 activity (the 11-year cycle), unusual episodes of solar activity
 (solar flares, etc.), stratospheric temperatures, sea surface
 temperatures, concentrations of various trace species, etc. etc.
 Now ask, which of these could produce something like the
 Antarctic ozone hole? The key point is that each of these mechanisms
 has characteristic signatures which you can look for. For example,
 solar effects should be most pronounced in the _upper_ stratosphere,
 whereas the ozone hole is confined to the lower stratosphere.
 Solar flares destroy ozone by producing NO radicals, but the ozone
 hole is characterized by unusually _low_ NO, etc. Stratospheric
 temperatures are decreasing, but if you examine the seasonal
 dependence of the ozone hole you find that the temperature decline
 _follows_ the formation of the ozone hole rather than precedes it,
 indicating that it is the lack of ozone that is cooling the
 stratosphere (by reduced UV absorption) rather than the reverse.
 Ozone destruction by chlorine-containing radicals has a very direct
 signature: you should see ClO. ClO is produced by the reaction of
 Cl with O3, there is no other significant mechanism for making it in
 the stratosphere (you can't make it from Cl and O2 or Cl and H2O
 because such reactions are way too endothermic.) So observation of
 ClO is a "smoking gun" for chlorine-catalyzed ozone destruction.
 Of course every one of these has to be quantified - you should be
 able to take the measured ClO concentrations and calculate, using
 independent data (measurements of reaction rates in the laboratory),
 what the ozone should be. That's what AAOE-1 did in 1987.

 Any theory for the antarctic ozone hole has to (1) be consistent
 with what is already known about stratospheric chemistry and
 dynamics (or make a good case for rejecting something that is
 regarded as "known"), and (2) explain its seasonal dependence
 (maximum in the spring, rather than winter or summer), its vertical
 dependence (near 100% destruction of ozone in the lower stratosphere,
 essentially no effect in the upper stratosphere) and, of course,
 why it's in the antarctic. Those criteria alone knock out most
 armchair speculation as well as some well-formulated theories that
 were developed before all the data was in. _Then_ it has to address
 the chemical evidence; it ought to explain why ClO, a product of
 the reaction between O3 and Cl, insists on showing up in large
 quantities where the O3 has been most intensively depleted. It's not
 inconceivable that such an alternative theory can be developed;
 maybe atmospheric chemists are just an unimaginative bunch. But it's
 a tall order.

 One other reason I used BCS as an analogy is that this is an
 example of a solid result embedded in a subject that, in
 general, is very difficult. When I took Solid State in grad school
 my instructor argued that we have a better understanding of
 (conventional) superconductors than we have of ordinary metallic
 conduction. Similarly, the antarctic ozone hole is simpler to
 understand than the mid-latitude stratosphere, let alone the
 much nastier troposphere. There is no analog of the ClO "smoking
 gun" for global climate change.

Index Home About Blog