[Federal Register Volume 61, Number 13 (Friday, January 19, 1996)]
[Rules and Regulations]
[Pages 1284-1286]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 96-587]
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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.
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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 ozone-
depleting 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.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.
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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
1. 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
CO2 decay response and future CO2 atmospheric concentrations
held constant at current levels. (Only direct effects are considered.)
[[Page 1286]]
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Global warming potential (time
horizon)
Species (chemical) Chemical formula --------------------------------------
20 years 100 years 500 years
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CFC-11................................. CFCl3 5000 4000 1400
CFC-12................................. CF2Cl2 7900 8500 4200
CFC-13................................. CClF3 8100 11700 13600
CFC-113................................ C2F3Cl3 5000 5000 2300
CFC-114................................ C2F4Cl2 6900 9300 8300
CFC-115................................ C2F5Cl 6200 9300 13000
H-1301................................. CF3Br 6200 5600 2200
Carbon Tet............................. CCl4 2000 1400 500
Methyl Chl............................. CH3CCl3 360 110 35
HCFC-22................................ CF2HCl 4300 1700 520
HCFC-141b.............................. C2FH3Cl2 1800 630 200
HCFC-142b.............................. C2F2H3Cl 4200 2000 630
HCFC-123............................... C2F3HCl2 300 93 29
HCFC-124............................... C2F4HCl 1500 480 150
HCFC-225ca............................. C3F5HCl2 550 170 52
HCFC-225cb............................. C3F5HCl2 1700 530 170
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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,'' and
do not reflect review of scientific documents published after that date.
[FR Doc. 96-587 Filed 1-18-96; 8:45 am]
BILLING CODE 6560-50-P
