February 28, 2007
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Global Climate Change Digest
A Guide to Information on Greenhouse Gases and Ozone Depletion
Published July 1988 through June 1999
FROM VOLUME 10, NUMBER 7, JULY 1997
OZONE DEPLETION: CFC SUBSTITUTES
"HCFCs and HFCs: Halocarbon Replacements for CFCs," P. Midgley
(M&D Consulting, Ludwigstr. 49, Leinfelden Musberg D-70771, Ger.), Atmos.
Environ., 31(7), 1095-1096, Apr. 1997.
Commentary on the success of the Montreal Protocol and the role the two
major CFC substitutes have played in that success. Concerns about the global
warming effects or breakdown products of HCFCs and HFCs are far outweighed by
what would have happened if CFCs had not been cut back.
"Estimated National Releases to the Atmosphere of
Chlorodifluoromethane (HCFC-22) During 1990," P.M. Midgley, A. McCulloch
(ICI Chemicals Ltd., Runcorn WA1 4QF, UK), Atmos. Environ., 31(6),
809-811, Mar. 1997.
Estimates for this most widely used substitute for CFCs are made using the
calculated emissions of CFC-12 as a surrogate distribution function. Releases so
calculated match the sparse published data in most cases.
"Atmospheric Chemical Reactivity and Ozone-Forming Potentials of
Potential CFC Replacements," G.D. Hayman (Natl. Environ. Technol. Ctr., AEA
Technol., E5 Culham, Abingdon, Oxfordshire OX14 3DB, UK; e-mail:
email@example.com), R.G. Derwent, Environ. Sci. & Technol.,
31(2), 327-336, Feb. 1997.
Addresses one of the environmental impact concerns relating to HCFCs and
HFCs before widespread production of them commences: their possible contribution
to ground-level photochemical ozone production. Calculations with a
photochemical trajectory model show that their contribution is probably low.
However, our ability to weigh the relative importance of this impact, along with
their impacts on stratospheric ozone depletion and climate change, is not
sufficiently developed to assess with any degree of certainty the benefits or
harm that may result from switching to the use of HCFCs and HFCs.
"GAGE/AGAGE Measurements Indicating Reductions in Global Emissions
of CCl3F [CFC-11] and CCl2F2 [CFC-12] in 1992-1994," D.M. Cunnold (Sch.
Earth & Atmos. Sci., Georgia Inst. Technol., Atlanta GA 30332), R.F. Weiss
et al., J. Geophys. Res., 102(D1), 1259-1269, Jan. 20, 1997.
Global Atmospheric Gases Experiment/Advanced GAGE observations of CFC-11
indicate that its global concentrations peaked in 1993 and decayed slightly in
1994; CFC-12 concentrations increased about 7 ppt in both 1993 and 1994. This
suggests that world emissions in these two years were smaller than industry
production figures would indicate and have decreased faster than expected under
the Montreal Protocol. The combined atmospheric loading of these two compounds
plus four other common chlorinated compounds reached a maximum in 1992.
"Replacement of Chlorofluorocarbons at the DOE Gaseous Diffusion
Plants: An Assessment of Global Impacts," M.L. Socolof (Energy Div., Oak
Ridge Natl. Lab., POB 2008, Oak Ridge TN 37831), R.E. Saylor, L.N. McCold, Environ.
Impact. Assess. Rev., 17(1), 39-51, Jan. 1997.
For Department of Energy uranium enrichment plants, analyzes replacement of
CFC-114 coolant with perfluorocarbons, which are less damaging to stratospheric
ozone but large contributors to global warming. The overall contributions of
coolant releases to ozone depletion and global warming were quantified by
parameters which are shown can be used as surrogates for predicting global
impacts to all resources. They can provide a framework for assessing
environmental impacts of a permanent coolant replacement, eliminating the need
for subsequent resource-specific analyses.
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