From: schloerer@RZMAIN.RZ.UNI-ULM.DE (Jan Schloerer)
Newsgroups: bit.listserv.biosph-l
Subject: Re: Ozone Depletion Myths
Date: 16 Dec 92 15:25:26 GMT
Reply-To: Jan Schloerer <schloerer@RZMAIN.RZ.UNI-ULM.DE>
Comments: Gated by NETNEWS@AUVM.AMERICAN.EDU

Jeremy Whitlock  (WHITLOCK@MCMASTER.CA)  wrote :

> Well, meditative healing of the ozone layer makes perfect sense, seeing
> how meditative destruction is the "cause" of the ozone hole in the first
> place.  When enough people focus on the idea that mankind has caused
> thinning of the ozone layer, this magically becomes fact -- regardless
> of the evidence that orders of magnitude higher amounts of so-called
> "ozone-depleting" gases are released by a single volcano.

Well, myths die slowly, with or without meditation.  One such myth is
that volcanoes are a major source of chlorine in the  *stratosphere*  -
and that's the part of the atmosphere where it counts.  I prefer Robert
Parson's wording to my clumsy English  (apologies to readers of sci.env
if you see this twice) :


-----   begin robert parson

From:          parson_r@cubldr.colorado.edu (Robert Parson)
Newsgroups:    sci.environment
Date:          Thu, 19 Nov 1992 04:33:51 GMT
Organization:  University of Colorado, Boulder


In article  <1992Nov18.203503.12198@gn.ecn.purdue.edu>,
            dyrda@gn.ecn.purdue.edu  (Richard Dyrda)  writes:

> Volcanic eruptions put out 1,000's upon 1,000's more ozone depleting
> chemicals than we humans have ever done. Since volcanoes have erupted
> for 1 billion years I think our ozone level is just fine.

No. Volcanoes are _not_ a major source of stratospheric chlorine.

Consider the two most famous eruptions in the past decade: El Cichon and
Pinatubo. We have direct measurements for these. According to one report
(Mankin and Coffey, _Science_  _226_, 170, 1983) El Cichon put *0.04* Tg
HCl into the stratosphere.  Another study found less.  Pinatubo, the
biggest eruption since 1912, coughed up much less  (Mankin, Coffey, and
Goldman, _Geophys. Res. Lett. _19_, 179, 1992).  In fact the effect was
so small they were unwilling to assign a quantitative figure; they only
concluded that it was much less than El Cichon (a factor of 4 or
more). An eruption like El Cichon occurs once a decade or so;
an eruption like Pinatubo occurs once or twice every century.

Chlorine emissions from CFC's and related manmade compounds came to
more than *1.2* Tg/yr during the 1980's, of which 0.9 Tg reached the
stratosphere (Prather et al., J. Geophys. Res. _95_, 18583, 1990).
These numbers do not include unknown amounts of emissions from the
Soviet Bloc and China.

Volcanoes are not even the principal _natural_ source - that
distinction goes to biologically produced CH3Cl. It contributes ~15%
of the Cl in the strat., CFC's and related compounds contribute ~75%.

Sure, volcanoes have been erupting for billions of years, but HCl
_does_ rain out of the stratosphere. Transport across the tropopause
is slow, but it's not _that_ slow!                     [ ... ]

-----   end robert parson


Jan Schloerer          schloerer@rzmain.rz.uni-ulm.de
Klinische Dokumentation           Uni Ulm
Postfach 3880     DW-7900 Ulm     Germany
Comments: Gated by NETNEWS@AUVM.AMERICAN.EDU