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<br />
<br />ROGER A. PIELKE, JR.
<br />
<br />Villdns. L.: 1996. 'Living with the Flood: Human and Governmental Responses to Real and Sym-
<br />bolic Risk', (Chapter 10), in Changnon, S. A. (ed.), The Gnat Flood of 1993: Causes, lmp<<cts,
<br />and Rtspon.fI!S, Westview Press, Boulder, CO.
<br />VMO (World Meteorological Organization): 1992, IfJtemational Glossary of Hydrology. UNESCO
<br />and WMO, Geneva. Switzerland.
<br />VDOd, R. A.: 1993, 'Fla.~h AoodIFlood State-by-St8Ic Fatality Statistics 1945-93', in Storm Data
<br />1993: A Composife ojOutswnding SlOrm~ 35(13), NOAA. WashinglOn, D.C~. pp. 80-81.
<br />NoOO. R, A.: 1994, 'Flash Flood/Flood Fatalities - 1960 through 1994 - Umted States., Puerto
<br />Rico and the Virgin Islands. Year-by' YearIState-by-Statc', in Storm Data and Unusual Weather
<br />Phenomena with Late Repor/.f and Corrections 36 (12), NOAA, Washington. D.C., pp. 56-58.
<br />Nrighl, J.: 1996, 'Effects of the Flood on National Policy: Some Achievements. Major Challenges
<br />Remain', (Chapter II), in Changnon, S. A. (ed.), The Greal FJoodof 1993: Causes, lmpaclS, and
<br />Responses, Westview Press, Boulder, CO.
<br />levin, S. F.: 1994, 'Steps Toward an Integrated Approach to Hydrometeorological Forecasting
<br />Services', Bull. Ama Meteorol. Soc:. 75(7), 1261-1216.
<br />
<br />IMPACTS ON GLOBAL OZONE AND CLIMATE FROM USE AND
<br />EMISSION OF 2,2.DICHLORO.I,I,I.TRIFLUOROETHANE (HCFC.I23)
<br />
<br />JAMES M, CALM '. DONALD I. WUEBBLES' and ATUL K, JAiN'
<br />
<br />1 Engineering Corl.\'ufwnt, 10887 Wood/euf LlIne, Greal Fall.f, Virginia 22066.3003, US.A.
<br />E.mail: jmc@~.peclrum.internel.com
<br />2Departmenl of Atmospheric Sciences. University of Illinois al Urbana-Champaign,
<br />105 South Gregory Sueel, Urbana, Illinois 6/801 -4723, U.S.A.
<br />E-mail: wuebbles@almos.uiuc.eduandjain@uiatma.allllos.uiuc.edu
<br />
<br />(Received 13 March 1998; in revised form 21 August 1998)
<br />
<br />Abstract. Analyses of emissions, and consequent chlorine loading, show that projected use of 2.2-
<br />dichloro-I,I.I-trifluoroethane (HCFC-123) will result in a virtually indiscernible impact on strato-
<br />spheric ozone. Parametric scenarios uphold this conclusion. even for extreme levels of emi.~_~ions far
<br />exceeding those of current technologies and practices. Additional scenarios reaffirm the conclusion
<br />for continued use - beyond the scheduled phaseout date - a.~ a refrigerant in closed systems. By
<br />contrast, use of this compound olTers unique opportunities to reduce global warming. Moreover,
<br />time-dependent analy.~e.~ show that the minimal contribution to stratospheric chlorine from HCFC-
<br />123 emissions will not peak until more than a decade after the residual peaks of chlorine and bromine,
<br />from prior chlorofluorocarbon and halon releases, subside. While no single index exists to compare
<br />the relative demerits of orone depletion and climate change, three conclusions are clear. First, reversal
<br />of the buildup of bromine and chlorine (i.e., healing of the 'ozone layer') is underway and progressing
<br />on target, while sufficient pnlctical remedies for global climate change are far more difficult. Second,
<br />the analyses show that phaseout of all chlorinated, and conceptually - but much less probably - all
<br />brominated, compounds of anthropogenic origin targets some compounds thai provide environmental
<br />benefits. Most chlorinated and brominated compounds do warrant phaseout; the exceptions are those
<br />with very short atmospheric lifetimes, and consequent low ozone depletion potential (ODP), that
<br />also offer offsetting environmental benefits. And third, since new global environmental concerns
<br />may, and probably will: be identified in the future, a more scientific approach is needed to determine
<br />environmental acceptability or rejection.
<br />
<br />1. Introduction
<br />
<br />Scienlific assessments and regulatory actions usually group organohalides by their
<br />molecular composition. These broad distinctions imply degrees of relative con-
<br />cern with. their potentials. upon emission, for depletion of stratospheric ozone.
<br />The chlorinated and fluorinated species are most commonly divided into the chlo-
<br />rofluorocarbon (CFC), hydrochloroftuorocarbon (HCFC), and hydrofluorocarbon
<br />(HFC) families (WMO. 1995; UNEP, 1993). These distinctions follow similarities
<br />in industrial applications and comparative magnitudes for ozone depletion potential
<br />(OD?) when released. As shown in Table I, which addresses the chemicals used
<br />and under consideration as refrigerants, the OOPs for these groups are of the order
<br />of I for CFCs, 0.01--0.1 for HCFCs, and less than 0.001 - approximately zero-
<br />
<br />~4. Climatic Chan,t:f' 42: 439--474, 1999.
<br />IJIlll' @ 1999 Kluwer Academic Puhli.rhers. Prillted in the Nerher/(/l1ds
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