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Protection of Stratospheric Ozone: Listing of Global Warming Potential for Ozone-Depleting Substances
[Federal Register: January 19, 1996 (Volume 61, Number 13)] [Rules and Regulations] [Page 1284-1286] From the Federal Register Online via GPO Access [wais.access.gpo.gov]
ENVIRONMENTAL PROTECTION AGENCY 40 CFR Part 82 [FRL-5400-3] RIN 2060-AF35 Protection of Stratospheric Ozone: Listing of Global Warming Potential for Ozone-Depleting Substances AGENCY: Environmental Protection Agency (EPA). ACTION: Notice of final listing.
SUMMARY: With this action, the Environmental Protection Agency (EPA or the Agency) lists the global warming potentials for ozone-depleting substances that are included as class I and class II controlled substances, or have been added as class I or class II controlled substances, under authority of section 602(e) of the Clean Air Act Amendments of 1990 (CAA). Class I and class II controlled substances are more fully described in a final rule previously published in the Federal Register on May 10, 1995 (60 FR 24970). To meet EPA's statutory obligation under the CAA, this listing cites the global warming potentials contained in the document, Scientific Assessment of Ozone Depletion: 1994, published by the United Nations Environment Programme (UNEP) in early 1995. As stated in the CAA, the listing of global warming potentials for class I and class II controlled substances ``shall not be construed to be the basis of any additional regulation under this Act.'' DATES: This rule is effective on January 19, 1996. FOR FURTHER INFORMATION CONTACT: The Stratospheric Ozone Hotline at 1- 800-296-1996, or Tom Land, U.S. Environmental Protection Agency, Office of Air and Radiation, Office of Atmospheric Programs, Stratospheric Protection Division (6205J), 401 M [[Page 1285]]
Street, SW, Washington, DC 20460, (202)-233-9185. SUPPLEMENTARY INFORMATION: I. Proposal As required by section 602(e) of the CAA, EPA published a notice of proposed listing on October 6, 1995, and solicited public comment. As stated in that proposal, EPA relied on three scientific documents in determining gobal warming potential (GWPs). EPA is referencing those three scientific documents and the list of GWPs they contain in order to meet the Agency's statutory obligations under section 602(e) of the CAA to publish GWPs for class I and class II controlled substances. These documents are also referenced in part, for their discussions of different radiative forcing indices and the indirect effects of ozonedepleting substances on radiative forcing. These documents demonstrate the state of knowledge and the uncertainties involved in calculating the GWPs for class I and class II controlled substances. The citation for the three scientific documents that report on GWPs for class I and class II controlled substances are: United Nations Environment Programme (UNEP), February 1995, Scientific Assessment of Ozone Depletion: 1994, Chapter 13: ``Ozone Depleting Potentials, Global Warming Potentials and Future Chlorine/ Bromine Loading;''
Intergovernmental Panel on Climate Change (IPCC), 1995, Climate Change 1994: Radiative Forcing of Climate Change and An Evaluation of the IPCC IS92 Emission Scenarios, ``Summary for Policymakers: Radiative Forcing of Climate Change,'' pages 32-34; and Daniel, John S., Susan Solomon and Daniel L. Albritton, January 20, 1995, Journal of Geophysical Research, Vol. 100, No. D1, ``On the evaluation of halocarbon radiative forcing and global warming potentials.'' Chapter 13 in the UNEP, Scientific Assessment and pages 32 through 34 in the IPCC, Summary for Policymakers describe the factors considered in calculating various radiative forcing indices, such as (1) the direct GWP, (2) the absolute global warming potential (AGWP), and (3) the net GWP per unit mass emission. Chapter 13 of the Scientific Assessment and the article by John S. Daniel, et al. in the Journal of Geophysical Research describe the indirect feedback effects of ozone-depleting substances on the temperature of the atmosphere, and therefore the potential indirect effects that depletion of stratospheric ozone has on the calculation of the GWP. The October 6, 1995 proposed listing contained a full discussion of the relevant science. That discussion will not be repeated in this notice. II. Comment on Proposal EPA received one comment on the proposed listing of GWPs for class I and class II controlled substances. The comment suggested that cautionary language be included in order to prepare the reader for changing scientific estimates of GWPs, citing work by the IPCC on the Second Scientific Assessment of Climate Change that will be published early in 1996. EPA adopted these suggestions and changed the caption to Appendix I accordingly.
No comments were received on the proposed GWPs. III. Listing GWPs for class I and class II Controlled Substances With today's action, EPA publishes the GWPs that are listed for class I and class II controlled substances in the Scientific Assessment of Ozone Depletion: 1994 issued by the United Nations Environment Programme (UNEP) under the auspices of the Montreal Protocol in February of 1995. The GWPs for class I and class II controlled substances as published in the Scientific Assessment are in Appendix I to Subpart A--Global Warming Potentials. As discussed in the October 6, 1995 proposed listing, the Scientific Assessment of Ozone Depletion: 1994 does not list a GWP for every controlled substance that is listed in Appendices A and B to Subpart A as most recently promulgated in the Federal Register on May 10, 1995. For some ozone-depleting chemicals scientists have not developed a full infrared spectrum that is necessary to calculate the relative radiative forcing potential of a substance. Each chemical absorbs the Earth-emitted infrared radiation in specific energy (or wavelength) bands determined by the quantum-mechanical properties of the specific molecule.<SUP>1 Scientists have not measured the spectral region in which some of the ozone-depleting substances absorb infrared radiation. In addition, more data must be collected on the tropospheric distribution and concentration of some of the chemicals, their atmospheric lifetimes, and the interactive atmospheric chemistry in order to complete a calculation of the global warming potential for the remaining ozone-depleting substances. Scientific centers and academic institutions throughout the world are undertaking the necessary measurements and studies that are needed to complete the calculations of GWPs for other ozone-depleting substances, as well as to revise GWPs for those substances listed in Appendix I. EPA believes it is not possible at this time to publish GWPs for every ozone-depleting substance listed in Appendix A and B to Subpart A because the necessary scientific information is not available. EPA will continue to evaluate GWPs for class I and class II controlled substances not listed in today's action, and revisions to the GWPs for substances that are listed, and as deemed appropriate, amend the listing through future actions. \1\ Wuebbles, Donald J., 1995, ``Weighing Functions for Ozone Depletion and Greenhouse Gas Effects on Climate,'' Annual Review of Energy and Environment, 20:45-70.
List of Subjects in 40 CFR Part 82 Environmental protection, Administrative practice and procedure, Air pollution control, Chemicals, Chlorofluorocarbons, Exports, Hydrochlorofluorocarbons, Imports, Ozone layer, Reporting and recordkeeping requirements, Stratospheric ozone layer. Dated: December 26, 1995.
Carol Browner,
Administrator. For the reasons set out in the preamble, 40 CFR part 82 is amended as follows: PART 82--PROTECTION OF STRATOSPHERIC OZONE
- The authority citation for part 82 continues to read as follows: Authority: 42 U.S.C. 7414, 7601, 7671-7671q. Subpart A--Production and Consumption Controls 2. Appendix I is added to subpart A to read as follows: Appendix I to Subpart A--Global Warming Potentials (mass basis), referenced to the Absolute GWP for the adopted carbon cycle model CO<INF>2 decay response and future CO<INF>2 atmospheric concentrations held constant at current levels. (Only direct effects are considered.) [[Page 1286]]
Global warming potential (time horizon) Species (chemical) Chemical formula -------------------------------------- 20 years 100 years 500 years CFC-11................................. CFCl<INF>3 5000 4000 1400 CFC-12................................. CF<INF>2Cl<INF>2 7900 8500 4200 CFC-13................................. CClF<INF>3 8100 11700 13600 CFC-113................................ C<INF>2F<INF>3Cl<INF>3 5000 5000 2300 CFC-114................................ C<INF>2F<INF>4Cl<INF>2 6900 9300 8300 CFC-115................................ C<INF>2F<INF>5Cl 6200 9300 13000 H-1301................................. CF<INF>3Br 6200 5600 2200 Carbon Tet............................. CCl<INF>4 2000 1400 500 Methyl Chl............................. CH<INF>3CCl<INF>3 360 110 35 HCFC-22................................ CF<INF>2HCl 4300 1700 520 HCFC-141b.............................. C<INF>2FH<INF>3Cl<INF>2 1800 630 200 HCFC-142b.............................. C<INF>2F<INF>2H<INF>3Cl 4200 2000 630 HCFC-123............................... C<INF>2F<INF>3HCl<INF>2 300 93 29 HCFC-124............................... C<INF>2F<INF>4HCl 1500 480 150 HCFC-225ca............................. C<INF>3F<INF>5HCl<INF>2 550 170 52 HCFC-225cb............................. C<INF>3F<INF>5HCl<INF>2 1700 530 170 do not reflect review of scientific documents published after that date.