From: solomon@chaos.utexas.edu (Thomas Solomon)
Newsgroups: talk.politics.misc,alt.activism
Subject: Re: Ozone problem burns Politically Correct
Date: 16 Apr 92 17:01:48 GMT
Reply-To: solomon@chaos.utexas.edu (Thomas Solomon)
Followup-To: talk.politics.misc
Organization: University of Texas at Austin, Center for Nonlinear Dynamics

In article <1992Apr12.211056.21928@anomaly.sbs.com> mpd@anomaly.sbs.com (Michael P. Deignan) writes:
>john@anasaz (John Moore) writes:
>
>>However, sometimes the reality happens to come down on their side, and
>>the ozone hole is one.
>
>That's debatable. Sure, there has been some measured decrease in
>atmospheric ozone isolated to particular regions of the world, but
>there is no evidence to prove that such depletions are man-induced.
>

From the abstract of "Free Radicals Within the Antarctic Vortex:  The
Role of CFCs in Antartic Ozone Loss," J.G. Anderson, D.W. Toohey, and
W.H. Brune, Science, Vol. 251, pp. 39-52 (January 1991):

    How strong is the case linking global release of chloro-fluorocarbons
    to episodic disappearance of ozone from the Antarctic stratosphere
    each austral spring?  Three lines of evidence defining a link are
    (i) observed containment in the vortex of ClO concentrations two
    orders of magnitude greater than normal levels; (ii) in situ
    observations obtained during ten high-altitude aircraft flights
    into the vortex as the ozone hole was forming that show a decrease
    in ozone concentrations as ClO concentrations increased; and (iii)
    a comparison between observed ozone loss rates and those
    predicted with the use of absolute concentrations of ClO and BrO,
    the rate-limiting radicals in an array of proposed catalytic cycles.
    Recent advances in our understanding of the kinetics, photochemistry,
    and structural details of key intermediates in these catalytic cycles
    as well as an improved absolute calibration for ClO and BrO concentrations
    at the temperatures and pressures encountered in the lower antarctic
    stratosphere have been essential for defining the link.

The rest of the article elaborates on what is written in the abstract,
providing proof that there is a "causal link between surface release of
CFCs and the massive loss of O3 in the Southern Hemisphere."

From the summary of the same article:

    What sets Antarctic O3 depletion apart in the context of global
    change is both the severity of the phenomenon and the unusual
    decoupling of physical and chemical time constants that control
    transformation rates in a specific region of the atmosphere.  We
    have presented a case in three parts based upon simultaneous,
    in situ observations of ClO, BrO and O3 concentrations designed to
    test catalytic processes coupling CFC release, which has elevated the
    stratospheric mixing ratio of chlorine from ~ 1 ppb in 1950 to
    ~3 ppb in 1990, to ozone depletion over Antarctica.  When taken
    independently, each element in the case contains a segment of
    puzzle that in itself is not conclusive.  When taken together,
    however, they provide convincing evidence that the dramatic
    reduction in column-integrated O3 over the Antarctic continent
    would not have occurred had CFCs not been synthesized and then added
    to the atmosphere.


From the abstract of "Progress towards a quantitative understanding
of Antarctic ozone depletion," Susan Solomon (no relation), Nature
Vol 347, p. 347 (September 1990):

    The possibility that the stratospheric ozone layer could be depleted
    by half at certain latitudes and seasons would have been deemed
    a preposterous and alarmist suggestion in the early 1980s.  A
    decade later, the statement is acknowledged as proved beyond
    reasonable scientific doubt.  Observations of the composition of
    the Antarctic stratosphere have established that the chemistry
    of this region is highly unusual because of its extreme cold
    temperatures, leading to a greatly enhanced susceptibility to
    chlorine-catalysed ozone depletion.

And, from the body of the same paper:

    It has long been recognized that chlorine can destroy stratospheric
    ozone, and that the use of chloro-fluorocarbons has led to a
    pronounced increase in the stratospheric chlorine content.  Since
    the late 1970s, several chloro-fluorocarbons have been measured
    at remote sites around the world.  The observed rates of systematic
    increase of compounds such as CFC-12 and CFC-11 in the atmosphere
    have been shown to be consistent with their known anthropogenic
    production rates worldwide, verifying that human activities
    represent the only significant source of these molecules and that
    their destruction occurs uniquely in the stratosphere.  By the early
    1980s, the chlorine content of the Earth's stratosphere had risen
    to about 2.5 parts per 10^9 by volume (p.p.b.v) compared to the 
    natural level of about 0.6 p.p.b.v, due largely to the oceanic
    release of CH3Cl.

The article includes references for each of the claims in this last
paragraph.

    Let me know if you need any additional evidence that artificially
produced CFCs are causing ozone depletion.  I have a list of some
more technical articles that illustrate this point.

    			Tom Solomon
                        solomon@chaos.utexas.edu