United State:*
Environmental Protection
"Agency
Office of Air and Radiation
Washington O.C. 20460
EPA 400/1-87/001A
December 1987
Assessing the Risks of
Trace Gases That Can
Modify the Stratosphere
Volume I:
Executive Summary
-------
Assessing The Risks of Trace Gases
That Can Modify The Stratosphere
Volume I: Executive Summary
Senior Editor and Author John S. Hoffman
Office of Air and Radiation
U.S. Environmental Protection Agency
Washington, D.C. 20460
December 1987
U.S. Environmental Protection Aser
•: '-'.•,i -% L'brary (".PL-16)
': •. •.'. D.^.'born SWeet, Room -i670j
CLioago, IL 60604
-------
Many people made this document possible.
A Science Advisory Board (SAB) panel chaired by Dr. Margaret Kripke and co-
chaired by Dr. Warner Horth conducted an extensive and constructive review of
diis document. Members of die panel provided important insights and assistance
in die assessments development. Members of the panel are:
Dr. Martyn Caldvell (Utah State University)
Dr. Leo T. Chylack, Jr. (Center for Clinical Cataract Research)
Dr. lien Dak Sxe (A.E.&.. Inc.)
Dr. Robert Dean
Dr. Thomas Fitzpfttriek (Massachusetts General Hospital)
Dr. James Friend (Drexel University)
Dr. Donald Bunten (University of Arizona)
Dr. Warren Johnson (national Center for Atmospheric Research)
Dr. Margaret Kripke (Anderson Hospital and Tumor Institute)
Dr. Lester Lave (Carnegie-Melon University)
Dr. Irving Miatzer (World Resources Institute)
Dr. Warner Hordi (Decision Focus, Inc.)
Dr. Robert Watson (Rational Aeronautics «nd Space Administration)
Dr. Charles Yentsch (Bigelev Laboratory)
Dr. Terry F. Yosie (U.S. turiiiuimmmtil Protection Agency)
The panel's contribution to die process of protecting stratospheric ozone has
been critical. We also want to diank Terry Yoaie, Director of die Science
Advisory Board, for setting up and helping to run die panels, and Joanna
Foellaer for helping to organize meetings.
Other scientists and analysts, too numerous to name, provided reviews of
early drafts of die chapters.
Production assistance, including editing, typing, and graphics, was
provided by die staff of ICF Incorporated, including;
Bonita Bailey
Susan MacMillaa
Mary O'Connor
Maria Tikmff of die U.S. Environmental Protection Agency, coordinated
logisticmf parts of diis
The cover photograph was supplied by die National Aeronautics and Space
Administration.
Technical support documents (Volumes VI. VII, and VIII) have been published
along with die first five volumes of die Risk Assessment. These documents are
not part of die official Risk Assessment, and have not been reviewed by die
SAB. Their publication is simply to assist readers who wish more background
dian available in die Risk Assessment.
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Alan F. Teraaura
Department of Botany,
University of Maryland,
College Park. MD 20742
Dennis Tirpak
U.S. Environmental Protaction Agancy.
401 M Street, S.V..
Washington, DC 20460
Jia Titus
U.S. Environmental Protaction Agancy,
401 M Street* S.W.,
Waahington. DC 20460
John B. Walla
Tha Bruca Coopany,
Suita 410. 3701 Hanachuaatta Ava.( B.V..
Vaahington, DC 20016
G. Z. ihittan
Syataaa Applications, Inc.,
101 Lucua Vallay Road,
San Rafaal, CA 94903
Robert Vorrast
Corvallia Environaantal Raaaareh Laboratory,
200 Southwaat 35th Straat,
Corvallia, OR 97333
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List of Conerlbators
Craig Ebarr
ICF Incorporated,
9300 Laa Highway.
Fairfax, VA 22031
Sarah Foatar
ICF-Claaant,
9300 Laa Highway,
Fairfax, VA 22031
Miehaal J. Ctbba
ICF Ineorporatad,
9300 Laa Highway,
Fairfax. VA 22031
Ravin Haarla
ICF Ineorporatad,
9300 Laa Highway.
Fairfax, VA 22031
Brian Hicks
ICF Ineorporatad,
9300 Laa Highway,
Fairfax, VA 22031
Patsy H. Lill
Dapartaant of Pathology,
Univarsity of South Carolina School of Madicina,
VA Bldg No. 1, Carnat Farry Rd,
Coluabia, SC 29208
Janica Longstrath
ICF-Clamant,
9300 Laa Highway,
Fairfax, VA 22031
Hail Fatal
U.S. Environswntal Protaetion Agancy,
401 H Straat, S.W.,
DC 20460
••ft M. Pitchar
V.T; ttnrirooMntal Protaetion Agancy,
401 M Scraat, S.tf.,
Vashington, DC 20460
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ORGAHXZalXOH*
This document summarizes a multi-volume assessment of tha risks of
stratospheric modification. Since the early 1970s, scientists have been
concerned that huaan activities could altar the composition of the stratosphere,
leading to raductions in the quantity of ozone protecting earth from the sun's
ultraviolet-B (UVB) radiation. If such raductions in ozona levels occurred,
public health and welfare would' be harmed.
Substantial scientific progress has baan made since concern about ozona
depletion was first raised. Ibis document represents a synopsis of currant
undarstanding of how ataospheric composition may changa, tha affects this changa
is likely to hava on ozona abundance and its vertical distribution, and tha
impacts of these changes in ozone en skin cancer, cataracts, suppression of the
iamune system, polymers, plants, sad aquatic systems. It-also examines related
changas in climate and tha potential impacts of climate changa on sea level
rise, agriculture, human health, water resources, and forests.
Despite significant improvement in our undarstanding of these issues,
substantial uncartaintias remain. Ibis risk assessment identifies and discusses
these uncertainties and, where possible, eetiaatea quantitatively their
potential significance.
Following a brief introduction, this summary volume is organized into five
sections:
o Summary findings (page ES-5)',
o Changes in atpnospharie composition covers chapters 2, 3, and
4 (page ES-15);
o Potential eh^ttgas iti ozone and climate covers chapters S 'and
6 (page ES-23);
o Hunan health, welfare, and environmental effects covers
chapters 7 through 16 (page ES-32); and
nt of rifles vith tacagracad •odel covers
chapters 17 and 18 (page ES-54).
Readers desiring greater detail are encouraged to refer to the five-volume risk
assessment and tha three volumes of die rr^Mt'**'1 support reports.
This_wssaary concludes with a briaf listing of aajor prior assassaents of
this
-------
TABLE OF UJHfUIS
PAGE
VOLDME I
ACKNOWLEDGMENTS , i
ORGANIZATION ES-l
INTRODUCTION ES-2
SUMMARY FINDINGS .'.... ES-5
CHARGES IN ATMOSPHERIC COMPOSITION ; ES-15
POTENTIAL CHANGES IN OZONE AND CLIMATE ES-23
HUMAN HEALTH, WELFARE. AND ENVIRONMENTAL EFFECTS ES-32
QUANTITAnVE ASSESSMENT OF RISKS WITH INTEGRATED MODEL ES-54
TABLE OF CONTENTS FOR FULL RISK ASSESSMENT ES-65
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Current scientific theory and evidence indicate that continued increases in
the concentrations of a variety of trace gases in the atmosphere .are likely to
aodify the vertical distribution and coluan abundance of stratospheric and
tropospherie ozone. Changes in the total abundance of column ozone would alter the
flux of ultraviolet radiation reaching the surface of the earth, and consequently
affect public health and welfare. Scientific evidence indicates that increases in
ultraviolet>B radiation (DV-B) would alter skin cancer morbidity and Mortality,
increase cataracts, and probably suppress the human insuine system. Evidence also
supports the conclusion that such increases could reduce crop yields and alter
terrestrial and aquatic ecosystems. Scientific theory and studies also support the
conclusion that polymers would be degraded sore quickly and that urban tropospherie
oxidants would increase as a result of UV-» increases, although additional
scientific study is needed to validate the possible effects on tropospherie air
quality. The dimensions of many of these risks are at this time unquantifiable.
Exhibit ES-1 susnarizes these relationships.
Changes in trace gases that can modify the stratosphere can be expected to
contribute to climate change in three ways: they are all greenhouse gases that
would increase global warming; by modifying vertical distribution of ozone, they
could change the Earth's radiative-balance and climate dynamics; by adding.water
vapor to the stratosphere, one of these gases (methane) directly adds to the
stratosphere's greenhouse or warming capacity, the effects of global warming
include changes in weather and climate patterns; rises in sea level; changes in
forests, hydrologic processes, and agriculture; and a variety of associated
impacts.
Current science projects that changes in ozone and climate will occur slowly
enough in the next decade that it is unclear that monitoring systems will be
capable of clearly detecting change, or of attributing changes to particular trace
gas increases. Because of the large lags expected between the emission of gases
and their ultimate effect on ozone and climate, the stabilization of atmospheric
concentrations and the prevention of further change would require large decreases
in trace gas emissions. Consequently, while monitoring can provide a valuable
system to test model projections, as well as to better understand atmospheric
systems, except in the ease of a larger than expected aaospheric change,
monitoring cannot be expected to provide definitive information about the nature of
future risks. With the exception of Antarctic ozone depletion, an unexpected and,
at this time, unexplained phenomenon, past monitoring supports current models.
which project that ozone depletion and climate change are likely to occur in the
face of grafJCa. in the concentrations of trace gases.2- It is important to recognize
1 This Risk Assessment was written before the results of the two Antarctic
campaigns were available and has not 'been revised to consider them. It now appears
that the Antarctic ozone hole is at least partly caused by man-made chemicals. The
implications for ozone in the rest of the world are unclear, depending on whether
the loss mechanisms operating in Antarctica are likely to operate elsewhere and on
whether Antarctic losses themselves might have global implications. Consequently,
until those issues are resolved, we cannot conclude that the 'hole' is a portent of
things to come elsewhere on the Earth. In the rest of this summary the original
Risk Assessment findings on Antarctica and trends are kept intact.
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EXHIBIT E8-1
Tho Baala for Conoorn About CFCa and Oxono Ooplotlon
CD Production of CFCa
(2) Emlaalona thon ooour
O) Conoontratlona buNd up
(4) Slow tranaport to atratoaphoro
(0) Pbotodlaaoolatlon of CFCa
roloaaoa chlorbio
ft) CMorlno oatalytleaNy
roduooa oxono
(7) Oiono doplotlon oauaoa
ohangoa In UV-B
(B) CFCa and ftolumn reorganization
ohanga tha attmata
Cauaal Chain:
(f) Incroaaoa In UV-B produeo affoeta
For oxamplo:
On okln oanoor
l"*
On Larval Northorn Anchovy
INCKASCO WV-i MWtfMM (»l
Production
EmJtilont
Conoon-
tratlona
Atntoaphorlo
Rotponao
** UV-B -
and oHmato
C?
Sourc«: HAS (|tf«), Icosto (I9M), mn* Hunt.t. R.upp .nd Uylor (INt).
-------
ES-4
chat "by ch« tine ie is possible to detect decreases ir. jzone concentrations
with a high degree of confidence, it n»y ba too l*ta to instituta corrective
measures that would reverse this trend* (EPA Science Advisory Board, March
1987).
-------
ES-5
last and Poaaible Future
1. Considerable research has taken place since 1974 when die theory linking
chlorine from chlorofluorocarbons (CFCs) and depletion of ozone waa first
developed. While uncertainties remain, die evidence to date continues to
support the original theory diat CFCa have the potential to decrease
stratospheric ozone.
2. Atmospheric measurements show that the chemical composition of the
atmosphere -- including gases that affect ozone •• has been et
Recently measured annual rates of growth in global
concentrations of trace gases that influence ozone include: CFC-11:
5 percent; CFC-12: 5 percent; CFC-113: 10 percent; carbon tetrachloride: 1
percent; methyl chloroform: 7 percent; nitrous oxide: 0.2 percent; carbon
monoxide: 1 to 2 percent; carbon dioxide: O.S percent; and prtfraw 1
percent. More limited measurements of Halon 1211 show recent annual
increases of 23 percent in atmospheric concentrations.
3. CFCs, Halons, methyl chloroform, and carbon tetrachloride release chlorine
or bromine into the stratosphere where they act as catalysts to reduce the
net amount of ozone. In contrast, carbon dioxide and median* either add to
die total column of ozone or alow die rate of depletion. The effect of
increases in nitrous oxide varies depending on die relative level of
chlorine.
4. CFCs, methyl chloroform, carbon tetrachloride, and Halons are industrially
produced. Emissions of mediane, carbon dioxide, and nitrous oxide occur
from bodx human activity and die natural biosphere. Because all these gases
(with die exception of mediane and mediyl chloroform) remain in die
atmosphere for many decades to over a century, emissions today will
influence ozone levels for more than a century. Also, aa a result of diese
long lifetimes, concentrations of diaae gasea will rise for more than a
century, even if emissions remain at constant levels. For example, to
stabilize concentrations of CFC-11 or -12 would require a reduction in
.current global emissions of about 85 percent. (Exhibit ES-2 demonstrates
effects of varioua reduction levels on CFC-12 concentrations).
5. In order to assess risks, scenarios of atmospheric change ware evaluated
usingledels. For CFCs, methyl chloroform, carbon tatrachloride, and
Halons, demand for goods that contain or are manufactured with these
chemicals (e.g., refrigerators, computers, automobile air conditioners) and
the historic relationship between economic activity and the uae of these
chemicals were analyzed. Theae analysea indicate that in the abaence of
regulation, the uae and emissions of these compounds are expected to
increase in the future. However, for purposes of analyzing risks, six
•what-if* scenarios were adopted that cover a greater range of future
production of ozone-depleting substance than is likely to occur.
-------
ES-6
EXHIBIT KS-2
CFC-12: AtBocpfaaric Cnnranrraciona
from Diffaranc Eadaaion Trajactoriaa
I
1
S
Constant
emissions
15% Cut
50% Cut -
85% Cut
1930
1985
2100
ration* of CFC-12 will c<
ua to riaa unlaaa aaiaaiona ara
Ataoapnaric • i-^ii —w—^-»^ »— —— — — _—
cut. Holding aadsaiona constant at today's l*v»l or avan 15 parcant or 50
parcant lowar would »till allow ataoapharie concantrationa to grow. Only a cut
of 85 parcant or aora could atabiliza ataoapharic coneantrationa.
Sourca: Hoffman, 1986.
-------
ES-7
Modal Projection for Ozone Changes
6. Ataospheric chemistry models were used to assess the potential effects of
possible; future changes in atmospheric concentrations of trace gases. Thes
node Is attempt to simulate processes that influence the creation and
destruction of ozone. While the Models replicate many of the
characteristics of the atmosphere accurately, they are inconsistent with
measured values of other constituents, thus lowering our confidence in thei
ability to predict future ozone changes accurately.
7. Based on the'results fro* these Models, the cause of future changes in ozon
will be highly dependent on future eaissions of trace gases.
One-dimensional models project that if the use of chlorine and bronine
containing substances remains constant globally, and other trace gas
concentrations continue to grow, total column ozone levels would at first
decrease slightly, and then would subsequently increase. If the use of CFC
continues to grow at past rates and other gases also increase at recent
rates, substantial total coluon ozone depletion would occur by the middle o
the next century. If the use of CFCs stays at current levels and the growt
in the concentrations of other trace gases slows over tine, model results
indicate total eoluan ozone depletion will also occur. (Exhibit
ES-3 shows various aodel projections for "what-if" scenarios.)
8. In all scenarios examined, substantial changes are expected in the vertical
distribution of ozone. Ozone decreases are generally expected at higher
altitudes in all scenarios in which CFC concentrations increase. Ozone
increases are expected at lower altitudes in soae scenarios exaained due to
increases in asthane concentrations. Such changes aay have important
cliaatic effects.
9. Two-dimensional (2-D) aodels provide information on possible changes in
ozone by season and by latitude. Results from 2-D aodels suggest that
global average depletion could be higher than estimates froa a
one-dimensional (1-D) model for the same scenario. Moreover, the 2-D model
results suggest that average annual ozon* depletion above the global averag
would occur at higher latitudes (above 40 degrees), while depletion over
tropics is predicted to be lower than tfam global average; and depletion
would be greater in the spring than tae manual average. Uncertainties in
the representation of the transport of chemical species used in 2-D models
intremmeee uncertainty in die magnitude of the latitudinal gradient of ozon
depletion, but all 2-D models project a gradient.
10. Measurements of ozone concentrations are another valuable tool for assassin
the risks of ozone modification. Based on analysis of data for over a
decade from a global network of ground-based monitoring stations, ozone
concentrations have decreased at mid-latitudes in the upper and lower
stratosphere and increased in the troposphere. According to studies using
ground-based instruments, there appears to have been no statistically
significant change in column ozone between 1970 sad 1983. High altitude,
lower stratospheric, and total column trends are roughly consistent with
current two-dimensional aodel predictions.
-------
ES-8
EXHIBIT ES-3
Global Awaraga
10.0
•50.0
1985 2009 2020 2046 2065 2089
*This acanario assunas no growth in global production of ozona daplatars, and
concantrationa of othar traca gasaa ara prawntad £roai rising to an aaount
graatar than that eoapatibla with an incraaaa in •quillbriiai global tavparatura
of 3.0°C ± 1.5«C«y 2075.
— Currant 1-D awdals accurataly raflact global daplation; Antarctic ozona hola
has no iapact on global ozona lavals.
.. Graanhouaa gaaas that countar daplation grow at biatorically-axtrapolatad
rataa.
-- Growth rataa for ozona daplatars ara for global amisslona; it is asauawd
that anisaiona do not incraaaa aftar 2050.
-- Ozona daplation limicad to 50 parcant.
-------
ES-9
11. Recent evidence indicates that since the late 1970s substantial decreases
ozone (up to 50 percent) have occurred over and near Antarctica during its
springtime. These losses have been verified by different measurement
techniques, and different theories have been suggested to explain the caus
of the seasonal loss in ozone. Insufficient data exist to state whether
chlorine and bromine are responsible for die observed depletion, or whethe
some other factor is the cause (e.g., dynamics or changes in solar flux th
•leers HOx). Furthermore, even if Ban-Bade chemicals are the cause of the
phenomenon, stratospheric conditions surrounding Antarctica are different
from the stratospheric conditions for the rest of the world, so that it
cannot be assumed that similar depletion would occur elsewhere. Models di
not predict the Antarctic ozone depletion, however. Consequently, the
change in Antarctica suggests that ozone, abundance is sensitive to yet
unknown natural or anthropogenic factors not yet incorporated in current
models. .
12. Preliminary data from Nimbus-7 suggest a decrease in global ozone
concentrations (4-6 percent) may have occurred during the past several
years. These data have not yet been published and require additional revi<
and verification. If verified, further analysis would be required to
determine if chlorine is responsible for the reported decrease in ozone
levels, or whether the decrease is due to other factors or reflects
short-term natural variations.
Potential Health Effects from Osoos Depletion
13. Decreases in total column ozone would increase the penetration of
ultraviolet-B (UV-B) radiation (i.e., 290-320 nanometers) reaching the
earth's surface. (Exhibit ES-4 shows relative increases in UV-B at 295,
305, and 315 nanometers.)
14. Exposure to UV-B radiation has been implicated by laboratory and
epidemiologic studies as a cause of two common types of skin cancers
(squamous cell and basal cell). It is estimated that there are more than
400,000 new cases of these skin cancers each year. while uncertainty exist
concerning the appropriate action spectrum (i.e., the relative biological
effectiveness of different wavelengths of ultraviolet radiation), a range <
relationships was developed that allows increased incidence of these skins
cancers Co bo estimated for future ozone depletion (these cancers are also
refer*** to as nonmelanoma skin cancers).
*
IS. Studied predict that for every 1 percene increase in UV-B radiation (which
corresponds to less than a 1 percent decrease in ozone because the amount <
increase in UV-B radiation, depending on die action spectrum, is greater
Chan rather than proportional to ozone depletion), nonmelanoma skin cancer
cases would increase by about 1 to 3 percent. The mortality for these fon
of cancer has been estimated at approximately 1 percent of total cases bas<
on limited available information.
16. Malignant melanoma is a less common form of skin cancer. There are
currently approximately 25,000 cases per year and 5,000 deaths. The
relationship-.between cutaneous malignant melanoma and UV-B radiation is a
complex one. Laboratory experiments have not succeeded in transforming^. _
-------
ES-10
EXHIBIT ES-4
Incraaaas in Ultraviolat Radiadon
Dua to a 1 parcant Ozooa Daplation
4-
2-
1 -
295
3OS
313
(nm)
Ozona daplation would laad to increaaaa in tha aaount of ultrcviolat radiation,
particularly at tha hara£ul lovar wavalangAa, Chat raaehaa tha aart±'» aurfaea.
Sourea: Estioates baaad on tha ozona-UV nodal davalopad by Sarafino and
Fradarick (1986).
-------
ES-11
aalanocytaa with UV-8 radiation. However, raeant epidemiological studies.
including large case control studies, suggest that DV-B radiation plays an
important-role in causing melanoma. Uncertainties in action spectrum, dos
measurement, and other factor* nacasaitataa the uaa of a range of
dose-response estimates. Taking into account such uncertainties, recent
studies predict that for each 1 pareant change in 0V-E intensity, the
incidence of melanoma could increaaa from 0.5 to 1 percent.
17. Studies have demonstrated that UV-B radiation can auppresa the
response system in «rfMl • and possibly h"~T*ir. While UV-B-induced iamune
suppression baa been linkad Co chronic reinfection with herpes simplex vin
and laiahmaniaaia in animals, its poaaible impact on other diseases and it;
impact on humans haa not bean studied.
18. Increases in exposure to UV-B radiation are likely to increaae the incident
of cataracta and could adversely affect die retina.
Potential Iffacts on Plants and Aquatic Organisms
19. While studies generally shov adverse impacts on planta from increased UV-B
exposure, difficulties in experimental daaign, the Hyf*** number of speci<
and cultivars tasted, and the complex interactions batwaen planta and thai:
environments prevent firm conclusions from being made for the purpose of
quantifying risks. Field studies on soybeans suggest that yield reduction:
could occur in some cultivars of soybeans, while erridanca from laboratory
studies suggest that two out of three cultivars are sensitive to UV-B.
20. Laboratory studies with numerous other crop spaciaa also show many to be
adversely affected by UV-B. Increased UV-B has baan shown to alter the
balance of competition between plants, while the magnitude of this change
cannot be presently estimated, the implications of UV-eltared, competitive
balance for crops and waads and for nonagricultural areas such aa forests,
grasslands, and desert may be far reaching.
21. Aquatic organisms, particularly phytoplankton, zooplankton, and the larvae
of many fishes, appear to be susceptible to harm from increased exposure t<
UV-B radiation because they spend at least part of their time- at or near
surface waters. However, additional raaaarch is needed to bettor wnderstai
the ability of these organisms to mitigate advetsa affects and any possiblt
impliavtiona of changes in I'l'iamnnf ry composition as more susceptible
organ**** decrease in numbers, Tha Implications of possible affects on thi
aquatic food chain requires additional study.
Effaces of Depletion on Tropoapfaarle OBona and Polymers
22. Research has only recently baan initiated into tha affects of UV-B on the
formation of tropospheric ozona (an air pollutant with negative health and
plant effects). An initial chambar and modal study shows that tropoapheri<
ozona levels could increaaa, resulting in additional urban areas being in
non-compliance with national Ambient Air Quality Standards. Tha increaae i
UV-B would also produce ozona peaks closer to urban canters, expoaing larg<
populations to unhealthy concentrations of tropospheric ozona. The same
study also predicts substantial increaaa in hydrogen peroxide, an acid.rail
precursor. However, because only one study has been done, the results, ausi
-------
ES-12
be treated with eaucion. Additional theoretical and empirical work will be
needed to verify these projections.
23. Research indicates that increased exposure Co UV-B would likely cause
accelerated weathering of polymers, necessitating polymer refemulation or
the use of stabilizers in SOM products, and possibly curtailing use of
certain polymer* in SOM areas.
24. The Rational Academy of Science* (HAS) has recommended diat 1.5°C to 4.5°C
represents a reasonable range of uncertainty about die temperature
sensitivity of die Earth to a doubling of C02 or an increase in odier trace
gases of die equivalent radiative forcing. While some of die trace gasea
discussed above deplete ozone and others result in higher ozone levels, all,
on net, would increase die radiative forcing of die Bardt and would
contribute to global warming.
25. Using die middle of die HAS range for die Eardi's temperature sensitivity
and a wide range of future trace gas growdi (e.g., from a phase-down of CFCs
by 80 percent from current levels by 2010 to a 5 percent annual increase
through 2050; C02 doubling by 2060; R20 increasing at 0.2 percent; CH4
increasing by 0.017 ppm/year through 2100), equilibrium temperatures can be
expected to rise from 4°C to 11.6°C by 2075. Of dlis amount, depending on
die scenario, CFCs and changes in ozone would be responsible for
approximately 15-25% of die projected climate change. (See Exhibit ES-5)
26. In most situations, inadequate information exists to quantify die risks
related to climate change. Studies predict that sea level could rise by
10-20 centimeters by 2025, and by 55-190 centimeters by 2075. Such
increases could damage wetlands, erode coastlines, and increase damage from
storms. Changes in hydrology, along widi warmer temperatures, could affect
forests and agriculture. However, lack of information about die regional
nature of climatic change makes quantification of risks difficult. A study
suggests diet rising temperatures could adversely affect human health if
acclimatization lags. *
4
27. To perfotsJHfca computations necessary to evaluate die risks associated with
stratosphesK modification, an integrating model was developed to evaluate
die Joint implications of scenarios or estimates for: (1) potential future
use of CFCs and change in other trace-gases; (2) ozone change as a
consequence of trace gas emissions; (3) changes la UV-B radiation associated
widi ozone change; and (4) changes in akin cancer eases and cataracts
associated widi changes in UV-B radiation. Potential impacts of
stratospheric modification that could not be quantified were not addreaaed
by die integrating model. On a global basis, die risks of ozone depletion
may be greatest for plants, aquatic systems and ^he immune system, even
though knowledge to asaess dteaa efforts is much less certain dian for skin
cancers.
-------
ES-13
EXHIBIT ES-5
Equilibria T<
trature
jig 3.0*C
for the Six teission Scanaric
for Doubled C02*
12.0
o
y
•
o
1
5.0% Growt
;: 3.8% Growt
2.5% Growt
1.2% Growt
I Growth
% Raduct
1985
1995
2005
2015
2025
2035
2045
2055
2065
2075
* Cooputad assuming that cha cliaata sensitivity to a doubling of carbon
dioxida is 3*C. This assuoption is in tha viddla of tha HAS rang* of l.S*C to
4.5*C (saa Chaptar 6). Nota that Cha actual waning that Bay ba raalized will
lag by savaral daeadas or aora. To eoaputa tha aquilibrium warming associated
with high or low HAS aatiaatas aultiply tha y axis 'taaparacura change' by 1.5
or 0.5.
Growth levels refer to global estimates of production of all ozone
dapleters. . -
-------
ES-14
28. Uncertainty about future risks is partly driven by the rata at which CFC and
Halon lisa and other trace gases grow or decline. For this reason, a vide
range of "what-if" scenarios of potential CFC and Halon use and growth in
trace gas concentration was evaluated. To reflect the large uncertainties,
the scenarios range froa an 80 percent global phase-down in the use of CFC*
by 2010 to an average annual growth in use of S percent par year fro* 1985
to 2050. For ozone-Modifying gasas other than CFCa, scenarios were based en
recently Measured trends, with uncertaintiea being evaluated by considering
a range of future emissions and concentrations.
29. Across the wide range of "what•if" scenarios considered, ozone change by
2075 could vary froa aa high as over SO percent ozone depletion to increased
abundance of ozone of approxiaatsly 3 percent. This rang* of ozone changa
iaplias a change in the nuaber of akin cancer eases aaong people alive today
and born through 2075 ranging froa an increaae of over 200 aillion- to a
decrease on the order of 6.5 aillion. The overwhelming Majority (over 95
percent) of the increases and decreases in akin cancer caaes estiaated for
this wide range of scenarios is associated with basal and squaaous cell
cancers (i.e., nonaelanoaa skin cancer). Mortality iapacts are estiaated-to
be on the order of 1.5 to 2.0 percent of the changes in total cases, and a
large percentage of the estiaated iapacts are associated with people born in
the future. The statistical uncertainty of these astiaatas is on the order
of plus and ainus 50 percent. Additional uncertainties exist, soae of which
cannot be quantified. The greataat single uncertainty about future risks is
driven by the rata at which CFC and Halon use grows or declines. This
uncertainty is reflected in the assessaent by «*«^fMTTg a wide range of
•what if" scenarios of future use.
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ES-15
2C
Tho sbuDdsaeo of stratospheric ozone depends upon chemical sad physical
processes that create and destroy ozono. For over a decade scientists have
hypothesized that changes in the concentrations of trace gases in the ataosph*
could possibly perturb the processes that control ozone abundance and its
distribution at different altitudes. The findings of this section suanariza t
currently available evidence on how esdssions and concentrations of various
gases aay change over tiae. The findings in this section can be found in
chapters 2 through 4 of the body of the risk assessasnt.
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ES-16
1. HUMAN ACTIVITIES ARE THE ONLY SOURCE OF EMISSIONS TOR THREE CLASSES OF
POTENTIAL OZONE -P1?T.irK; CHEMICATJg •
CHLQROCARBOHS (CARBON TET[frftpfl^jftlDE ***& METHYL EHTflPf}fQRM^ ; Afifl
(chapters)*.
la. Sine* their development In the 1930s, CFCs have become useful
chemicals in « wide rang* of consumer and industrial goods, including;
aerosol spray cans; air conditioning; refrigeration; foam products
(e.g., in cushions and insulating foaas); solvents {e.g.,
electronics') ; and a variety of miscellaneous uses.
Ib. CFC-11 (CC13F) and CFG -12 (CC12F2) have dominated the use and
emissions of CFCs, accounting for over 80 percent of current CFG
production worldwide. Because of increased *^w* for its use as a
solvent, CFC-113 (CC12FCC1F2) has become increasingly important as a
potential ozone-depleting chemical.
2. MEASTME^FyTfi Qf TROPOSPHB^Te CONCENTRATIONS OP IMPPSTgTALty
POTENTIAL OZONE-DEPLETING GASES SHOP SUBSTANTIAL INCREASES (chapter 2).
2a. Measurements of current global average concentrations of CFC-11 are
200 parts per trillion volume (pptv), CFC-12 are 320 pptv. CFC-113 are
32 pptv, carbon tetrachloride (CC14) are 140 pptv, and methyl
chloroform (CH3CCL3) are 120 pptv.
2b. Based on measurements from a global monitoring network, worldwide
concentrations of chlorine-bear ing perturbants (i.e., potential ozone
depleters) have been growing annually in recent years at the following
rates: CFC-11 and CFC-12 at 5 percent; CFC-22 (CHC1F2) at 11 percent;
CFC-113 at 10 percent; carbon tetrachloride (CC14) at 1 percent; and
methyl chloroform at 7 percent.
2e. Limited measurements show that global tropospheric concentrations of
Halon 1211, a bromochlorofluorocarbon containing both chlorine and
bromine (which is potentially more effective at depleting ozone), have
been growing recently at 23 percent annually. Concentrations have
been measured as one pptv.
2d. KeaeVmeents of tropospheric concentrations of Halon 1301, another
bromVmted compound that is a potential ozone depleter, estimate that
concentrations are approximately one pptv. 86 trend estimates have
been published.
2 The chapter references refer to die main body of the risk assessment.
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ES-17
3. ALMOST ftf^, EMISSIONS OF CTC-ll. -12. -11?, HAVQN 1211. AND HALON \301
PERSIST IN THE; TROPOSPHERE WITHOUT CHEMICAL TRANSFORMATION OR PHYSICAL
DEPOSITION. AS A RESULT. MOST OF THESE EMISSIONS UT1T. EVENTUALLY BE
TRANSPORTED TQ THE STRATOSPHERE (chapter 2).
3a. Gases which are photochemically inert accumulate in the lower
atmosphere. Their emissions migrate to the stratosphere slowly.
Estimates of their atmospheric lifetimes (generally calculated base
on the time when 37 percent of the compound still remains in the
atmosphere) are the following: CFC-11 is 75 years (107/58 years);
CFC-12 is 111 years (400/55 years); C7C-113 is 90 years; CC14 is SO
years; Halon 1211 is 25 years; R20 is 150 years; and Halon 1301 is
110 years. (Where provided, the range in parentheses shows one
standard deviation).
3b. Because of their long atmospheric lifetimes, the concentrations of
these gases are currently far from steady state and will increase
over time unless there is a large reduction in future emissions.
3c. Because of their long atmospheric lifetimes, these gases would
continue to contribute to possible future ozone depletion and climai
change (CFCs and other gases affecting ozone are also greenhouse
gases) long after they are emitted. Full recovery from any depletii
or climate change would take decades to centuries.
4. WHILE CFCa TTSED IN AEROSOLS PBCLYNED FROM 1974 PHTTL 1984. NONAEROSOL USE!
OF CFCa HAVE CROWN CONTnTOOPSLY AND APPEAR CLOSELY cntpT.Eft TO ECONOMIC
(chapter 3).
4a. From 1960 to 1974, the combined production of CFC-11 and CFC-12 froi
both aerosol and nonaerosol applications grew at an average annual
rate of approximately 8.7 percent. Total global CFC-11 and -12
production peaked in 1974 at over 700 million kilograms.
4b. From 1976 to 1984, sales of CFC-11 and CFC-12 for aerosol
applications declined from 432 million kilograms to 219 million
kilograms, an average annual rate of decline of over 8 percent.
During'the same period, sales for nonaerosol applications grew from
318 million kilograms to 476 million kilograms, an average annual
compounded growth rate of 5 percent. By 1986, total CFC-11 and -12
.** global production was nearly that in 1974.
g PRQPPCTTQH OF CTC«-11 AMD .12
>f
(chapter 3).
•ATE OF APPBOyTMATRtY l.Q TO 4.0 FERCEHT OVER THE HETJ IS TO 65
5a. A large number of studies of future global demand for CFCs were
conducted by experts from six countries under the auspices of the
United Rations Environment Programme. These studies used a variety
of methods for estimating both near- and long-term periods. In
general, these studies assumed that: (1) demand for CFCs was drive:
by economic factors; (2) no additional regulations on CFC use were
imposed; and (3) consumers or producers do not voluntarily shift awj
from CFCs because of concern about ozone depletion. These studies
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ES-18
provide a rang* of growth rates for developing alternative baseline
scenarios of future CFC use and emissions.
5b. In general, these'studies projected that CFC aerosol propellant
applications would remain constant or decrease further in many
regions of the world. . «, — •:-*•. .-.=
5c. In die U.S. over the past four decades new uses of CFCs have
developed first in refrigeration, then ia aerosols, then in -foam
blowing, and then in solvents.
* •
5d. Studies have projected that growth ia developed countries for
aonaerosol applications is expected to bo driven by increased use in
foam blowing (primarily for insulation) and aa solvents, and by the
continued introduction of new uses. The wide raage of estimates of
future growth reflects the large uncertainties related to population
and economic growth, and technological change.
5e. Studies suggest that future CFC use in developing countries will grow
faster (i.e., at a higher rate) than future CFC use in the developed
world. Nevertheless, the .projected rates for the developing
countries are lower than the historical rates that have been
experienced in wealthier countries. Vhila these studies were done
using aggregate relationships of GRP and CFC use, they made different
assumptions about how closely the pattern of CFC use in developing
nations would replicate the pattern ia developed nations, generally
assuming lower use rates. However, evidence from one recently .
completed study (not completed at the time of the UHEP workshop)
indicates that in developing countries the penetration of CFC-using
goods may be occurring faster than expected on the basis of the
historical relationship in developed nations. If that study is
correct, growth in developing nations would be larger than projected
in the above-mentioned studies, which generally assumed less
penetration in developing nations than had occurred in developed
nations. . i3 %.
- 4. •"
5f. Three long-term studies of CFC demaad^peport annual average rates of
growth for CFC-11 and CFC-12 over cj^mext 65 years ranging from 0.2
percent to 4.7 percent, with a median, eetimate of about 2.5 percent.
it-if* scenarios used for ouaatitati.vc risk assessment
18 spaa a wider range of growth, including one scenario with
decline. -\ :• ~
5g. Limited studies on CFC-113 and CFC-22 project that ia the absence of
regulation or-voluntary shifts away from these ehemirilt. their
growth will increase at a faster rate than CFC«11 and -12 as new
markets develop and existing ones expand («.g., use of CFC-113 as a
solvent in metal cleaning).
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ES-19
6. THE Q^iQRflCARBQMS (METHYL. CHTflBOTOBM ASP CJSRMff TETRACHLDRIPE^ ARE USED
ppTMA»TT,Y AS SOLVENTS ACT CHEMICAL imTBMP^TA'rgs -._- ASALYSIS SUGGESTS
nn*UR£ CRQtTTH FOR THESE CHEMICALS (ehaptar 3) .
6a. Ma thy 1 chloroform IM primarily uaad aa a general purpose solvent.
Global use in 1980 was estimated at naarly 460 million kilograms.
Limited analysis of future demand indicates that it is expected to
grov at the rate of growth of economic activity (as measured by GNI
Factors affecting future demand include possible control on it or
other solvents due to their health effects. Thus, use' of methyl
chloroform could increase if other solvents are found more dangerot
Similarly, its use could be increased if..CFC-113 use is restricted.
Because methyl chloroform has a substantially shorter atmospheric
lifetime than CFC-113, it has relatively less potential for depUti
ozone.
6b. Carbon tetrachloride is primarily used to make CFCs in the U.S. Ir
developing countries it is also sometimes used as a general purpose
solvent. In general, future production and emission of carbon
tetrachloride is expected to follow the pattern of production of
CFCs.
7. RALPHS. °tf A PP* MOHP RASTS. POSE A
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ES-20
7f.
Diaeuaaiona with Halon uaara indieaca that Halon 1301 emission* may
be uadaraatimatad in tha study uaad for this riak aaaaeament. A
racanc survey showed that axisting systems ara undergoing vidaapraad
taating and accidancal discharge occurs more fraquantly than assumed
in prior studies.4
Additional analyaia of Halon emiasion eatlmataa an nacaaaary to
aaaaaa more adequately the riaka aaaociatad with tfaia traca gaa.
BTOGEffTC SOURCES CAftBON DTOTTTJB MCTHANP. Aim IHTIMMIV flflrTTW APT nTPPTrTTTT
(chaptar 4).
The size of axisting source terms (wetland
Cor
le) is not
known with eartainty today for all thaaa traea apaeiaa. Graataat
uncartainty axists for methane, laaat for C02. To eatimata futura
emissions raliably roquiraa estimating the growth of aourca tans
(a.g., acraaga of riea paddiaa, wetlands area), which will ba
datarminad by oany tachnical, political. anvironBantal, and social
factors.
Currant amission factors for aach aourca tars sjuat ba aatiaatad; a
ara not known today or hava not baan raliably astiMtad (aaissiona
from soils, for axaapla).
8b.
8c. Possible changes in amission factors due to changes in
environment must be projected. Projection of changes is difficult
because tha underlying physical or biological processes that
determine emissions ara not well understood and because changaa in
the environment that could altar amiaaiona are not easy to project.
8d. Biogeoehemical cycles that control tha fate of ealaaions once
released into tha atmosphere must be understood to determine futura
concentrations of these traca species; severe limitations to our
current understanding of theae cyclea limits our capacity to
determine the consequences of «*•**§*«•§ emissions in the future.
8e. Possible changes in theae biogeocbeaiJcal cycles due to changaa in the
•ast be projected; again^wjofleianciai in existing
makes this task difficult. '
USED TV THTS VT«P A
'»« OTTT RV
rr AQ
(AT
SCENARIOS TO gXAMTNE THE SCTS
SCEHARIQS (chaptar 4).
ITIVITY
OF A
1C KVOIDTTOH TO THE
4 Since this risk assessment was originally completed, Halon users in the
U.S. hava taken a variety of steps to reduce amiaaiona. this atep is
considered in this Risk Assessment.
-------
£5-21
9a. Tbm scenario* used in this risk assesisjeut are consistent with that
cosswnly used by the ataocpheric i ne»mili]i and assune the following
changes in trace gas concentrations:
o for C02, a scenario developed by the National Acadesy of
Sciences (its 50th pereentile, i.e., pre- industrial C02
ations doubling by about 2065) ;
for CH4, a linaar increase la concantzationa of 0.017 ppa
par
o jfor H20, concentration increase* of 0»2 percent per year.
9b. Additional scenarios used to analyze risks will include:
• for C02
o HAS 25th pereentile (pre- industrial concentrations
doubling by 2100)
o HAS 75th pereentile (pre •industrial concentrations
doubling by 2050)
• for CH4
o 0.01275 pp» per year growth in concentrations (75
percent of the historically observed 0.017 ppa per
year increase)
o 0.02125 ppm per year growth in concentrations (125
percent of the historically observed 0.017 ppa per
year increase)
o 1 percent compound growth per year in concentrations
o 1 percent compound growth per year in concentrations
fro* 1985 to 2010, followed by constant concentrations
at 2.23 pp»
_ o 1 percent compound growth per year in concentrations
from 1985 to 2020, growing to 1.5 percent
annual growth by 2050 and thereafter
• for 820
o 0.15 percent per year compound growth in
concentrations
o 0.25 percent per year compound growth in
concentrations
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ES-22
10. DECISION MAKERS SHOPLD BE MADE A«*gP JftAT THE MOST COMMONLY USED SCENARIOS
TK STttATOSTOCTTC *nPET.THC TMMJCTTLY ASSUME THAT TOTlBtg PECISION MAKERS
NEVER TACT AflTTQH TQ 1.TMTT THE RISE IH CONCENTRATIONS OF CARBON PIQ3CIDE.
METHANE. ACT) HTTROPS QYTpg, THff8^ CASES COHTRIMTTMC TO THE CgEENHOTISE
WARMING (Ch*pt«t 4).
10». Th« standard aasuvptlon in aosc ataoapharie Modeling baa b«an, by
dafaulc, thac graanhouaa gaaaa will b« allowed co ineraaaa vithoat
liait ragardlaaa of tha laval of global waning chat occur* or ia
projactad.
lOb. In ordar to provida daciaion makara with adaquata information to
aaaaaa tha riaka of ozona modification due to riaing CFCa and Halona..
altarnativa aaaumptiona about tha futura of graanhouaa gaaaa naad to
ba axaminad. Two acanarioa ara
— limiting global warming to 2°C.
-- limiting global warming to 3°C.
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ES-23
pg THE ATMPSPffggg tHAT TMCOgPQttATK
ATTOHS GROW STCSTyTCAirrT^r TMCBTAlIg ABODT MACiTLIPES REXAIM lARCg.
Hodals chat laeorporata eorr«nt scientific undarataaOiag ar« us«d as th«
primary tool to project th« potential consaqumcas of futura changes in
abundances of trace cases. These models can be partly tea tad by coopering their
results vith measurements of the ataospherie, historically observed changes in
ozone, and in the case of climate, with paleoclimatic and extraterrestrial
environments. While current models accurately represent some aspects of the
atmosphere, they fall to replicate other characteristics . This section
summarizes the currently available evidence on how changing atmospheric
abundance could modify total column ozone, altar column distribution, and change
global climate.
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ES-2&
11. STRATOSPHERIC MODELING PROJECTS THAT THE COMBINED gSTgCTS OF A VARIETY OF
TRACE CASES f CTfl^gflpFUTOROCARBONS. SITROUS tMCIPg. CARBON PTQTTMj,
AMP METHANE) ARE LIKELY Tt) BTOnCE THE COLUMN PBtSITV OF Q2OWE
EMISSIOMS OF Q2QEE PgPLETEES AM PgETPTTEP fMM CMgT»e (chapter 5).
11*. Photochemical theory continues to support tfao conclusion that
chlorine, nitrogen, and hydrogen can catalytieally destroy ozone in
the stratosphere, thus depleting coluan levels.
lib. One-dimensional (1-D) Models currently predict a 5-9 percent
depletion for the equilibrium concentrations of chlorine that would
result froa constant emission of CFCa at 1977 levels. while useful
for intercemparing Bodels, these values cannot be used to assess die
risks of depletion in an atmosphere in which other gases are also
changing.
lie. One-dimensional (1-D) models predict average column ozone will
decrease if global emissions of CFCs and other ozone depleters
continue to rise from current levels, even if concentrations of
methane, carbon dioxide, and nitrous oxide continue to grow at past
rates. For a 3 percent growth of CFCs, models predict over a 25
percent depletion by 2075 if the other gases continue to grow.
lid. Two-dimensional models (2-D) used in steady state multi-perturbant
studies that include chlorine, methane, and nitrous oxide project
depletion higher dun global averages at latitudes greater dun 40°H,
especially in die spring.
lie. Time-dependent simulations of stratospheric change in which 2-0
models are used predict dkat depletion over 4 percent will occur at
some latitudes for all eases of positive growth in CFC emissions.
Such models even predict ozone depletion of up to 3 percent at
inhabited latitudes for a scenario in which emissions of chlorine-
bearing substances are reduced from current to 1980 levels and in
which halon emissions are eliminated, but in which die greenhouse
gases dtat counter depletion are •lleweil to grow at historical ratea.
llf - Timm»4ependent simulation widt one 2-D model, widi CFCs growing at 3
pexisjmt, medians rising at 1 percent, nitrous oxide at 0.25 percent
anensmrbon dioxide growing at 0.6 percent, projects annual average
depletion at 40°H of approximately 1.1 percent by 2000 and 5.2
percent by 2030. At 50°H. depletion is projected to be 1.5 percent
by 2000 and 6.5 percent by 2030. At 60°H, depletion is projected to
be 2.1 percent by 2000 and 8.1 percent by 2030. Springtime depletion
would be higher.
llg. Time-dependent simulation widi one 2-D model, widi CFC-11 and -12
emissions rolled back to 1980 levels, CFC-113. capped, odiar
chlorinated emissions and bromine emissions eliminated, methane
rising at 1. percent, nitrous oxide at 0.25 percent, and carbon
dioxide at 0.6 percent, projects depletion by 2030 of about 0.5
percent at 40°N, 0.7 .percent at 50°N, and 1.1 percent at 60°N (dtese
-------
ES-25
depletion values ara from 1985 levels) . If carbon dioxide
concentration* ara prevented from growing from currant levels,
depletion would, ba anticipated to ba higher.
llh. Time-dependent simulations with two otfaar evo-dimensional models sho
roomily comparable raaults to choc* raportad hate, with a slightly
laaa latitudinal gradient. However, thaaa models also project
latitudinal gradianta from equatorial to polar aad ragiona.
Hi. Bacauaa of poaaible increases in the emiaaiona of bromine molecules
(see Chapter 4} , Halona praaant a more important riak for
stratospheric daplation than baa generally boon appreciated.
12. enagfur THEORY Aflft ffipy^* TATT. fn
OF TME ATMQSPHEBE AMP PROCESSES THAT gTLl. TMtUBfOt STBATQSPBgRIC CHANCE 1
A COMPLETE AMP ACCTOATE HAMMER (chapter 5).
12a. while accurately reproducing many meaaurements in die currant
atmosphere, currant modala fail to reproduce aoma measurements; the
amount of ozone at 40 kilometers is undareatlmatad, for example.
12b. while including representations of moat atmospheric proeeaaea,
it modala fail to include all the proeeaaea that influence
stratospheric compoaition and-structure in a realistic manner.
Transport processes, for example, ara rapraaantad in a simplified
manner that does not oncompaaa all the complications of movement in
the real afiaaaphara.
12c. The inability of modala to wholly reproduce measurements of the
current atmosphere lowers our confidence in them to predict the
future; it is possible that models ara over- or under-predicting
future depletion.
13. UNCERTAINTY ANALYSES THAT COWS T DP A BeltCT QF fO^^TIItJ! VATTTBg POP (THEMTCAL
AMD PffyffTflATi TW^Ffffs GftlTICAla PQft wiflftyj^ MSTTmyroM Of OKyT^ETTOH rHPTCA"f£
13a. Uncertainty analyses conductmdjro&i ooa-dimenaional models predict
daplation for a variety of CFC levels.
13b. fccartainty analyses uaing different aets of kinotiea and cross
fractions have not bean tested in two-dimensional modala. However,
different 2-D models have used different approachea for transporting
species. This providaa a useful teat of the aenaitivity of modal
predictions to the uncertainty of how transport actually works.
while differing somewhat in the latitudinal gradianta of depletion,
the models with different transport both predict daplation that
increases with distance from the equator.
13c. Not all uncertainties can be tested in .the modeling process. The
possibility that missing factors may laad to a greater or lesser
depletion than indicated in formal uncertainty analysaa cannot be
excluded. * ...
-------
ES-26
PREPTCTTOHS. giTH TBO EXCEPTIONS (chapter 5).
14*. Measurements by balloons and Uakehr ahov 3 percent depletion at
aid-latitudes in the upper ataoaphara, 1.3 percent depletion in the
lover stratoaphara, and 12 percent increaaee ia die lower
troposphere. Uncertainty exists about the accuracy of all these
observations. These results, huwevat. ara roughly consistent with
the expectations generated by one-dlaensional and two-diaanaional
aodela. The ground based measurement ayataa covers only a small part
of the Earth and ia liaitad at high latitudes.
14b. Niabus 7 measurements appear to show a decreaaa ia global ozone,
especially at both poles. However, the decrease ia Arctic ozona froa
1978 to 1984 aay have occurred only ia tha last aavaral years.
Concern exists about calibration probleas, which make an exact
determination of the absolute magnitude of daplation difficult.
However, the latitudinal variations in depletion seea to indicate
that a raal phenomenon ia being observed, not just instrumental -
drift.
14c. The cause of these apparent ozone decreases measured by Hiabua 7 has
not been sufficiently analyzed to determine whether the changes (if
they are real) can be attributed to manmsrte rhaalrala. Othar
possible explanations include natural variations caused by solar
cycles or other processes. The latitudinal gradients of the changes,
are, however, roughly consistent with those projected by 2-D model
results, although the mffgrl***"1* is substantially larger than models
predict. Until further analysis is performed to determine whether
depletion is actually occurring and whether it can be attributed to
man-made chemicals, models to asseaa risks to tha stratoaphere should
not be revised.
14d. Measurements in the Antarctic spring show that tha gradual depletion
that occurrad ia the mid-1970s over and near Antarctica haa given way
to a steep non-linear depletion £roaT.f79 to 1985. The ozone maximum
outside Antarctica (between 50°S and 70°S) appears to ba shoving a
decline. Tha daplation of all szaas^wooth of 80°S appears to ba 16
percent.
14e. Moeflb with conventional chemistry do not pradict "the Antarctic
osoas hale.* Care should be exercised ia interpreting the meaning of
tike phanoaanon. Several hypotheses have boon put forward, InrluiHng
* rtiaalral explanation that attributes tha loss of ozona to maT»aria
sources (bromine and chlorine), a chemical explanation that
attributes the loas to natural sources (10x, solar cycle), or an
explanation that claims tha phanoaanon is entirely duo to the change
in cliaate dynamics. Until more is understood about the true cauaea
of the hole, it ia iapossible to determine whathar tha hola ia a
precursor of atmospheric behavior that win occur la othar regions of
tha world. Until a better understanding of the aorhanlsas creating
tike depletion is obtained, the existence of the Antarctic ozona hole
should not be used as a basis for asking regulatory decisions.
-------
ES-27
14f. This risk assessment will assuma that Antarctic oxon* and global
tread* have no implications for global projection*. Future ravi*vs
should update this conclusion as naeassary.
15. TWgggAOTg Tfl Ttnt ABCTlPAHCg OF CFG* AHP OffflKR TRACTS CASK CAM HfCRE*3E
ffT/TBAT. TBOpOSpHKBJC SHItPACB 'l'jmi*EAA3TlR2S. TJffiSK (SASZS CAM AUHEa^THE
VEBTTCAT. nTffTgTItnTTCTT OF QZQtTE AND THCRgASK STBATPfiPHEgTC gATffP VAPOR.
15a. Trace gasas that act as stratospheric parturbaats also ara graenhouai
gases-res their concentrations increase in' the troposphere they will
retard tha escape of infrarad radiation from earth, causing global
15b. Incraaaaa la s*thana (CB4) will also add vaear vapor to tha
stratoaphara, tharaby ^W~»-*«n; global wsraiTig. Bathana iacraasas
will also add ozona to tiia tropoapbara, vhar* it acts as a strong
graaahousa gas that will furthar iacraaia global warming.
13c. In all modal-generated scenario* of oxona daplation, oxona dacraasaa
in tha stratosphara shove 28 km. This allows more ultraviolet
radiation to penetrate to lowar altitudes whara da •self-healing
effect' increases oxona to partially compensate for the oxone loss
abova. In some scenarios sufficient depletion occurs so that oxone
eventually decreases at all altitudes.
ISd. Decreases in oxona at approximately 28 km or abova will have a
warming affact on the Barth. There is a small nat gain in energy
because the increase in ultraviolet radiation (TJV-B) allowad to reach
die earth'* surf sea more than compensates for tha infrared radiation
that is allowad to aseape due to daplatioa of oxona above that
altituda.
15a. Balow approxiaataly 28 ka, incraasas in oxona ara mor« affactivs as
absorbars of infrarad radiation. Consaquantly, ineraasas in ozona
balow 28 km also will produca * nat warming. la this caaa, th*
additional TJV blockad by mora oxoaa ia lasa taaa taa additional
infrarad that is blockad from ascsplng tha aarth. Coararsaly, a
ia ocona balow 28 km will tand to cool tha Earth'* surfaea.
ISf. £tt dixact affact of column daplation of oxona on global tamparaturcs
1U1 dapand on tha aagnituda of tha daplatioa. Until tha daplation
is of sttffieiant •rcrl^"1* that it occurs at tha lowar part of' th*
column, oxoa* daplatioa will ba a aat contributor to global warming.
If tha stratosphara coatiauas to daplata so that oxon* is daplatad
balow 28 km, this daplatioa will causa a cooling. Oaa-dimansional
modal* diffar from two-dimanaional modals ia tha Wrtical
distribution of oxona changa, with daplation occurring at all
altitudas in tha highar latitadas in two-dimaasionsl modals, rathar
than Just at high altitudas. Thus, according to 2-D modals, sha
chsngas ia radiativa balanca will ba latitada dapandant. At tha
currant tima, no studias hava baan undartakan to dstsrmiaa ch« nat
radiativo forcing of chaagas projactad* by 2-0 modals.
-------
ES-28
15g. Radiative forcing way vary atrongly with changes in ozone at
diffarant altitudes and latltudaa. Consequently, until comparisons
ara made between tha models in terms of thair global impact,
eatimatea of* tha affaeta of changes in tha vortical colian of ozone
on global warning mada. with 1-D model* must ba viewed cautiously. In
addition, changed vertical *** ycrtbuttop of ozom cviild influence
stratospheric dynamiea.
^QEES ASSQCTAJ8P
LY (chapter
16a. Two National Academy of Sciences panels have concluded that the
equilibrium warming for doubling atmospheric concentrations of 002,
or for an equivalent incraaaa in tha radiative forcing of other trace
gasea, will moat likely be between 1.5° and 4.5°C.
16b. Tha magnitude of warming that would ba directly associated with
radiative forcing from increases in trace gasas without feedback
enhancement would increase temperature by approximately 1.2°C for a
doubling of 002, and approximately am additional 0.45°C for a
simultaneous doubling of H20 and- CB4. Direct radiative forcing
a uniform 1 ppb increase in both CFC-11 and CFC-12 would increase
temperature by about 0.15°C.
16c. The initial warming from direct radiative forcing would change
of tha geophysical factors that determine the earth's radiative
balance (i.e.. feedbacks will occur) and these changes would amplify
tha initial warming. Increased water vapor and altered albedo
affects (snow and ice malting, reducing tha reflection of radiation
back to apace) have bean projected by aeveral modeling groups to
increase die warming by aa much aa 2.5°C for doubled 002 or its
radiative equivalent. Large uneartaintiaa exist about the
feedbacks between global warming and clouds, which could further
amplify, or possibly reduce, tha r^g******1^ of warming.
16d. Tha three major general circulation modeling groups in tine D.S.
aatimata an average global ••^•ftvg of. aopound 4°C for doubled 002 or
its radiative equivalent. Itowavarf. because of uncertainties in the
of the cloud contributes**, greater or lesser
amplifications, including a negative gaedback that would reduce the
.to 2°C or an even lower value, nsniwir ba ruled out.
""IP1
GMlE*
16*. ClaMpfcavaraga temperature has been earl mat-ad as having risen about
O.il1 •••! the last century. 'This incraaaa is consistent with
ganaral predictions of climate models. Attempt• to use these data to
derive empirically the temperature sensitivity of tha earth to a
greenhouse forcing are not likely to aueeeed. uncertainty about die
past concentrations of trace gaaaa in the atmosphere, other exogenous
factors that affect the climate (such as aerosols or solar input),
jyd oscillation *r*** InTtihiliTl^f 5** the internal dynamics of the
climate system (such as ocean circulation). currently prevent die
derivation of the earth's temperature sensitivity from examination of
tha historic.rise of temperature. This limitation is likely to
remain for more titan another decade.
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ES-29
16f. The global warming associated with increases ia ozone-oodifying gases
varies with scenarios of future growth in these gases. If the use o:
CFCs grows at 2;5 percent per year through 2050. C02 concentrations
grow at the 50th pereentile rate defined by the HAS (approximately
0.6 percent per year from 1985 to 2050). 120 concentrations grow at
0.20 percent per year, and CB4 concentrations grow at 0.017 ppm per
year1 (spprtrnimafs ty 1«0 parcant of currant concentrations), then
equilibrium temperatures would riaa by about 5.6°C by 2075 (relative
' to observed temperature in 1985), based on a temperature eenaitivity
of 3°C for doubled G02. Valuaa would be about 50 percent higher for
a 4.5°C-baaed tamperatura sensitivity and about 50 percent lower for
1.5°C. If CFC use remains constant through 2050, tha projected
warming would be about 4.3°C by 2075 (± 50%). and if use were phased
out by 2010, projected warming would be about 4.0°C (± 50%).
16g. Efforts to gather worldwide time series data for clouds have begun.
If adequate, these data may narrow estimates of the cloud
contribution to temperature sensitivity within the next decade.
However, because of the complexity of t&is issue, this effort aay
fail to resolve the large uncertainties affecting thia aspect of
climate.
17. THE TIMING Of CrLOKAL yAJPfTP*? OTi^f^^ °^ **** MATIS AT VHTCH CggglHOPSt
THE RATES AT WHTOf CmtfS. FORCINGS fflCfl Ag YOMftlWKi? *^P SOIAR
(THAMfiT AKT» TVR 9ATV AT BHTffll OCKA1K TACK tTP 0JCAT AMB VABTTAtiY
PHA?
iY TEKPERATURZ
THT*8 PART
ASP SOIAR FACTORS PO MOT snBST^p^i^y pgAja^K (chapter 6).
17a. The delay in tamperatura riaa introduced by abaorption of heat by tho
ocaana can only be roughly eatimatad. Tba aimple one-dimensional
modela of oceana that have been uaad for thia purpoaa do not
realistically portray the aartianltmt for beat transport into tha
ocaana. Instead, these models uaa eddy diffusion to treat heat in a
parameterized manner so that beat absorption ia consistent with data
from the paths of tranaieat tracers. These modela indicate that the
earth will experience anbstantial delays (on tha order of several
decades) ia experiencing the ^jMadaf tram jxeeubuuse gaaea.
17b. .lha earth'a currant average rmmjsi-sfuri ia mvt-in equilibrium with
the radiative forcing from current concentrations of greenhouse
quently, global average tamperatura would increase in
future even if conceatrationa of gases did net rise any further.
for example, if 2°C ia the actual sensitivity of the earth's climate
system to a C02 doubling, simple modela eatimate tba currant
•unrealized warming" to be approximately 0.34°C; for a 4°C
temperature sensitivity, the currant unrealized warming would ba
approximately 1.0°C.
17c. Only one three-dimensional general circulation model baa been used tc
simulate changes in temperature aa concentrationa of greenhouse gssea
increase over time. This simulation shows a faster warming than
predicted by'-simpler one-dimensional modela that use ocean box modal4
to simulate time-dependent warming. '*' ~
-------
ES-30
17d. Future uptake of heat by the oeaana «ay ehaaga aa global wanting
altars ocean circulation, poaaibly altariag tfaa dalaying affaet of
tfaa oeaana aa vail aa radueiag their uptaka of C02.
17a.
Inadequate information exiata to predict how volcanic or solar
forcings may change over time. Analyses done of transient warming
assume that peat levela of volcanic aeroaola «ill continue into the
future and diet aolar forcing changea will average out over
relatively abort period* of
18.
CUTMATTC OtA
ASSOCIATED OTTH
AA'
Ml WTTAft.TV'
IKBTi
(chapter 6).
18a. In general, as the earth
with increasing distance from the equator.
be greater
18b. Global warming alao can be expected to increase precipitation and
evaporation, intensifying the hydrologieal cycle, while models lack
sufficient reliability to make projections for any single region- all
perturbation atudies-with •three-dimensional models (general
circulation models) show significant regional ahifta in dryneaa and
wetness, which suggests that ahifta in hydrologie conditions will
occur throughout the world., •
18c. Current general circulation sjodela represent oceanic, bioapherie, and
cloud proceesea with insufficient realism to defenrtne bow extreme
weather events and climatic norms are likely to change on a regional
basis. For example, one analysis of general circulation model
outputs suggests that the frequency of extreme climatic conditions
will change in many regions of the world. Another model projects
increased summer drying in mid-latitudes for perturbation studies,
utilizing either of two different repreaentatioaa of clouds. Still
another analyaia suggests changea in latitudinal gradients of aea
surface temperature will play a critical role in determining regional
climatic effecta. .* ' .
-. - is. -
19a
19b.
•that is, chloroflt
and aitrous oxides—would
decreaae the rate and magnitude of global warming. .
Oecreaaea in methane amisaiona, which have the potential to
stratospheric and tropoapharic ozone and thereby buffer ozone
depletion, would decreaae warming in three ways: by reducing direct
radiative effecta from its presence In the troposphere; by lowering
water vapor in the stratosphere; and by reducing
28 km.
build-up below
-------
ES-31
19c. Decreases in C02 emissions vould decrease global warming. but would
also have the effect of increasing the stratoaphere's vulnerability
to ozone depletion.
19d. Decreases in carbon monoxide concantrationa , which may occur as
energy production practices change, could result in decreases in
•ethane concantrationa by increasing OH* radical abundance which , in
turn, would shorten the lifetime of methane and could shorten the
lifetiae of methyl chloroform and C7C-22.
20. APPTTTOHAZ* RBSRARCH TS ffEJEDED Off CTJDCA.TR TO ftlfflCJGy PMC8SJA-Llff.LBS A&QUT
ctjOBAj. VABMTMC ASSOCTATFP WITH TSACT CAS
-------
ES-32
HKAItXH, BKUttlS* JUID
CHANCES TH COIXMH SE ABDHPAMCT AMP PTSTBTMTnOH AMP A »TSg TH G
CTKP TO HAM BBiAff HEAUHi WtfAEBi AHD THE
CAW M" CPAJfl I f I Uli TTSTHC BASCKS UTHU RTSTtS
CARROT BE QQAfTIKIED OR DATA WBCKi'T^AKT ^^ onAifliyiCATTQff Agg
(MfLY FOB 'LTMTTED CASE STHPTRS.
Ozoiw «hi«ld« th« ««rth froa UV-B radiation. A dacraaa* in total
coition ozone will increase this radiation, •specially *« ic* »o»t haraful
wavelengths. For the DKA action speconsm, a 1 percent depletion would
increase the weighted UV flux by about 2 percent. Changes in coluom ozone
and increases in global temperatures could altar aany environBental
conditions. The findings of this section cover the effects of these
changes on human health, ecosystems, crops, materials, air pollution, sea
level and other areas that influence human welfare.
-------
ES-33
ruu)j
21. BASED ft* SURVEYS (PARTICULARLY in THE uHjTBtf STATES AMD IN
5W EXPOSURE IS CONSIDERED TO BK THE POMimilT RISK FACTOR FOR
SKIN TUMORS (chapter 7).
21*. Nonas lanoaa «kin tueors tend t» develop la sun-exposed sits* (e.g.,
the head, face, aad neck).
21b. Higher incidence rats* occur eaong groups. subject to greater exposui
to tha sun'* rays because of occupations -that necessitate Chair
working outdoors.
21c. A latitudinal gradioat exists for UV-B radiation, and higher
incidence cat** of nnns»linnM skin tnaors generally occur in
gsographie aroas of roladwlj high UV radiation «xposura.
21d. Skin pignontation providaa a protsctiv* barrior that rtduca* the rij
of dowloping nonMlanoaa skin oasors.
21o. Tho riak of nnnsxltnosii skin tuaors is nighast sjwng gonotically
prodisposod individuals (o.g., thoa« wiA xarodars* pigBMntosua).
21f. A prodisposition to dowlop nonaolinnai skin tuaors axists aaong
light'Skinnad individuals (skin phonotrpos I and II) who ar«
suscaptibla to sunburn and vho bar* rod/blood hair, bluo/graan «y«s,
and a Celtic haritago.
22. f^f^U£lJ^ ^f'nfXIOLDBTC^L ffVTPEHCg qmTCArgg tTIAT T^B{ JBD HAJOR TYPES Of
HOMMELAHQMA SXTtt Ty^Ogg , SOOAMOpff CBTJi CAlCIHOMA (SCC1 AMP
CARCIKOMA. < >cc^ . SOLAH.
mJ) THAT COMniATIVE 0V ftADIATTOU HAS A. CggATtB. gPPgCT OH
PEVgLQgMEMT OF SCC THAN QM BCC (ehaptar 7).
22a. Tha BCC/SCC incidanca ratio dacrsasoa vith docroastng latituda and
Charafora, incraaslng UV lavala.
22b. BCC is s»ra likaly to davalop on normally unaxposod sitas («.g., tha
trunk) cosyarad to SCC.
22e. SCC is sora likaly than BCC to darelop on sitaa racaiving tha highest
oavolativo UV radiation dosaa <«.g. , tha noaa) .
22d. for a givan eusulativ* laval of sunlight axposura, tha risk of
developing SCC may be greater than tha risk of developing BCC.
23. fur B;»^T1LTS VftOM SgTgffAJ, EaTSyff**^^- ^™P^*S SUGGEST THAT PV-S MAY fK THE
MOST IMPORTANT COMPQMgMT f\V ^flTAB BAnTATTOS! THAT CAHSKS VARTATTOWS Tff THE
acnmcg OF noimgLMiOMA ej^i T^nf g (ehaptar 7).
23a. UV radiation producaa m-jnaelinnais skin tuaors in sniaals. DV-B
tlangths have been shown to be s»st affective in producing these
-------
ES-34
23b. UV-B has been shown to cause a variety of DHA lesions, to indues
nsoplastie transforaation in colls, and to bo a autagen in both
and baetsrial calls.
24. SEVERAL RESEARCHERS HAVE INVESTIGATED TH1 OUHCES Til TUB INCIDENCE OF
THAT MAV BV^ITTT verm TWCBKACM TW
fly RADIATION. GIVEN UMCERTA.TWTTES, BAHCES OF BTiJIATES OF IHC8EASEP
TNCTPENCE THAT COULD OCCDR gTTH DgKJTTQII AM KSTTMATm (chapter 7).
24a. The action spoetra for initiation and proaotion of basal cell and
squaaous- esll skin cancer have not been precisely doterained.
Fhotocare'inogenie studies indicate that the erytheaa and DHA action
spectra span a range likely to eneoapass that of squaaous cell and
basal cell skin cancer. The Bobertson-Berger (s>B) aster, while
providing useful data for describing aabieat UV radiation, does not
relate as closely to those wavelengths thought to proaote sunburn and
skin cancer.
24b. Several studies have provided estiaates of a biological amplification
factor (BAF), which is defined as the percent change in tumor
incidence that results froa a 1 percent change in UV-B radiation.
The results froa six studies produced an overall BAF range that is
1.8-2.85 for all nonaelanoaa skin tuaors.
24c. BAF estiaates are generally higher for aales than for feaales and
generally increase with decreasing latitude. In addition, the BAF
estiaates for SCC are higher than the BAF estiaatas for BCC. This
finding is consistent with observations that the BCC/SCC ratio
decreases with decreasing latitude and that BCC is aore likely to
develop on unexposed sites.
24d. Optical amplification (the change la UV-B radiation related to ozone
depletion) increases the response of these cancers to ozone
depletion, because the relevant action spectra increase aore than 1
percent for a 1 percent depletion. For exaaple, a 1 percent
depletion has an optical amplification of over 2 for die DKA action
speet
24e. Uncertainty exists in the actual doses of solar UV radiation received
by aaaulitions and in the statistical estiaates of the dose-response
coapRcients. Therefore, a range of estiaates Bust bo developed for
la .incidence associated with changes in dose.
24f. Currently available nonaelanoaa aortality data are of uncertain
accuracy because of the discrepancy of reporting between death
certificates and hospital diagnoses sad the lev proportion of deaths
reported on both hospital diagnoses sad death certificates. Based on
published studies, the rates of aetastasis among SCCs and BCCs have
been estiaated to be 2-20% and 0.0028-0.55%, respectively. The
overall case fatality rate for nonaelanoaa skin tuaors is
approximately 1-2% with three-fourths to four-fifths of the deaths
attributable to SCC.
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ES-35
24g. Changes in behavior have tended to increase skin cancer incidence &i
mortality. While soae evidence exists that this is reaching a li»i
tMn cancer rates, even in the absence of ozone depletion, would be
likely to rise. Future rates of skin cancer could be reduced if
people changed their behavior. Care should be taken, however, in
interpreting such a change- aa a 'coat- free' response.
c •
23. CDTAMgQPS MAt-TCWAMT mrLUJOHA (Qflf) JlSf \ gfRTQPS LTyr«THP1tATENIt«i DISEASE
THAT APVEL.TS A LARGE MMBER OF fTOFLIS T* ™ "JTTP f**™8 - THKRg ARE
T FORMS Qg MgLAIiOMA THAT ABB Limy TO HAVE SOMEWHAT
ETTOt/iCTES AMP RgtATTQMSHIPS tQ SOLAR ABB OV-8 ttAPlATTOH (chaptC
8).
25a. CMM incidence and mortality is Increasing rmnng fair-skinned
populations. These increases appear not to be Merely the result of
improved diagnosis and reporting.
2Sb. In 1987, it is estimated that there will be an estimated 25,800 cas«
of CMM and 5,800 fatalities related to melanoma la the United State »
In die absence of ozone, depletion, the lifetime risk of QfM in the
United States is expected to be about 1 in 150.
26. E.TMTTATIQNS IH THE n*Tfc1U.je» V9VMV3fT AASOTjDTl CpCTACTTY ABOUT TOE
BAPTAT V-R. ASP CPTAOTOPS
(chapter 8).
26a. There currently is no aniaal sjodal in which exposure to UV-B
radiation experimentally induces •elsncem.
26b. There is also no experimental ia ^H.trn model for malignant
transformation of melanocytas.
26c. Ho epidemiologic studies of QOC have been conducted in which
individual human UV-B exposures (and biologically effective doses of
solar radiation) have been adequately assessed.
27 KVAT.TTATIQN OF THlt RPTPPMTOLQCTCAL AND KLfRltTMPlTAL. PAIABASRS FOR MELANOMA.
IP PQSg AHP T(
(chapter 8) .
— . -. .
27a. Osone differentially removes wavelengths of BV-B between 295 end 320
-»»; OV-a, (320-400 nm) in wavelengtha above 350 •«• ia not removed, no
ia visible light (400-900 OB). Ozone removes all OV-C (i.e. ,
wavelengths leaa than 295 oa).
27b. Bavelengths between 295 oe and 300 at are generally more biological!
effective (i.e., damage target molecules in the akin, including DHA)
than other wavelengths in QV-B and even more so than TJV-A, radiation.
27e. Latitudinal variations exist in solar radiation; model predictions
indicate that the greatest variability ia seen la camulative UV-B
(e.g., monthly doses) followed by peak UV-B (highest one-day doses)
and then cumulative UV-A. Peak UV-A does aoc vary significantly
-------
ES-36
acroaa latitudaa up to 60*H. Craatar ambiant variation alao axiata
in UV-B than in UV-A by tima of day.
27d. Tha biologically affactiva doaa of radiation that actually raaehaa
cargat molaculaa dapanda on tha duration of axpoaura at particular
locations, tima of day, dma of yaar, bahavior (i.a., in tarma of
elothaa and sunscreens), pigmantation, and otbar charaetariaties of
tha akin including tamporal varlationa (a.g., fhangaa in pigmantation
dua co canning). .-*r'~:~~f"~? , \ • "
27a. Cloudinaaa •••*** albado, although cauaing larga ^"^T^icm? 1^ tha
amount of -axpoaura to UV-B and UV-A, do not graatly *»V"f» tha ratio
of UV-B to UV-A.
- ,
-------
ES-37
develop rates approaching those of prior (but native born) imaigran
to the adopted country; this is particularly accentuated in
individuals arriving before the age of puberty (10-14 years).
28h. It has been suggested that QfiC risk may be associated with childhoo<
sunburn; other evidence suggests that childhood sunburn may reflect
an Individual's pigmentary characteristics or may be related to nevi
development, rather than being * separate risk factor.
t
281. Most studies that have used latitude as a surrogate for sunlight or
UV-B exposure have found an increase la the incidence or mortality <
Qttt correlated to proximity to the equator. A recent -study of
incidence using measured UV-B and Qtf survey data found a strong
relationship between UV-B and incidence of QM. Another study that
used modeled UV-B data and an expanded database on mortality found i
strong UV-B/mortallty relationship.
28J. One form of QQC, Hutchinson's melanotle freckle, appears almost
invariably on tike chronically sun-damaged skin of older people.
29. SOME EVTPEHCg ^RfjftTBS VHffRTftTTrTT ABCPT TUB fflffnfiTTff^Hiy Bgrvgai SOLAR
RADIATTOW AMP COTAHttQPS IJALTflWfT MgLAMQtfA. (chapter 8).
29a. Some ecologic epidemiology studies, primarily in Europe or close to
the equator, have failed to find a latitudinal gradient for QM.
29b. Outdoor workers generally have lower incidence and mortality rates
for QOf than indoor workers, which appears incompatible with a
hypothesis that cumulative dose from solar exposure causes CMK.
29c. Unlike basal cell and squamous cell carcinomas, most QM occurs on
sites that are not habitually exposed to sunlight; this contrast
suggests that cumulative exposure to solar radiation or UV-B is not
solely responsible for variations in GMM.
30. UV-B RAPIATTOK IS * T.TgTTV COM KM Ml' O* SOLAS BAPTATIQS THAT CAPSBS
R TOBODffl T
(chapter 8)
CnTAMFOlTS MAtTCMAJn* tOJAVrttli SCMn . 'S1TTHKU TH8OPCH TWTTTATTON fff TUMORS OR
30s. Xaroderma pigmentoeum patients M» fall to repair UV-B-induced
•vyrlmidine dimers in daeir MA-feave a 2,000-fold excess rate of CMM
by the time they arm 20.
30b. UV-B Is the most active part of the solar spectrum in the induction
of wflffsgynfrsi* *r>*^ transformation £a. ylcro.
30c. UV-B is die most active part of die solar spectrum in die induction
of csrcinogenesis in experimental ••*<••*• and is considered by most
to be a causative agent of nonmelanoma skin cancer'in humans.
30d. UV-B is die most active portion of die solar spectrum in Inducing
immunosuppression, which may have a role in melanoma development.
-------
ES-38
30e. The limitations in the epideaiologie and experimental database leave
doubt as to the effectiveness of UV-B wavelengths in causing
31. UHTT.E TmCEBTAIMTY EXISTS. PK^fi^SfjS, ™ *™ IHCIPiHCg AMD HQETAT.TTY OF
MAT TOVAIIT MELANOMA ABC TJgKLv AS A RSSITLT OF OZONE BEFLETTOH.
dST fE.C.. MtBMMBC ACTilsH SFECT8A. PEAK VERSUS
CDMPLATTVE DOSE. KTC.i ABOUT THE «ATPBK OF THE KgtAtiOBMlMlP
AMP MFLAMOMA. THE FACT THAT Off-B lADTATIQB VA1TES AgQSS TffE EMVTBONMEST III
THE RAMCT OF VABTATTnH tTP»"fgf> »MH MFLgTTOM MOVtMS
TMFEgFgCT. PTPe«OLfflfTg THFTB?'*'"011 «""« ^P «TTHATg A BA
CHAHCES TIT TMCTPEMCK AMD MORTALITY IF THK omit LATKM. TS DEPUTED (chaptoe
31a. Uncertainty exists about the appropriata action spectrum to be used
in estimating dose, the best functional fora for dose-response, and
the best way to characterize dose (peak value, cumulative summer
exposure, etc.). Histologically different QMs (or possibly QJK _
located at different anatomical sites) are likely to have different
dose-response relationships. Most estimates of Qtt dose-response
relationships fail to consider these histologies! or site
differences. Nonetheless, by encompassing a range of possibilities,
it is possible to estimate doee-response because of die systematic
variations in UV-B.
31b. A recent study by die NIB presents a well-designed ecological study
of melanoma and UV-B using survey data and aeasured UV-B at ground
level. Vhile uncertainties exist, dxis dose-response relationship,
when used with different action spectra aad assuaptions about die
importance of peak versus cumulative exposure, can be utilized to
estimate a range of values for cases. The relationship estimates
Chat a 1 percent change in ozone is likely to increase incidence by
between slightly less than 1 to 2 percent, depending on die choice of
action spectrum. The appropriate action spectrum is likely to be
in die range of erydMaa and DBA.
'!•: .*-.'.
31c. Melanoma mortality is estimated at about 25 percent of all eases.
This result is consistent widi the jcojeetions of a dose-response
of mortality developed by EPA/BCI. It is eatimeted diet a 1
change in ozone would result la between a 0.3 aad a 2.0
change in CMM aortality depending en die assuaptions about
the appropriata dose and UV weighting functions aaed in the model.
3Id. Additional uncertainties for projecting future incidence and
aortality of OM in the U.S. include the lack of aa adequate database
describing variations in skin pigmentation and human sun-exposure
behavior among different populations and estimates of how these
relationships may change in die future.
^9 TI9 • gl!DDI*F*!Cge 1>UV TMMTINF gVgTBM TV AVTWAT **1MB I MKI^B /t&trnnfmf Q\
JA. uv»B_ayjrj'|UodiLa_^ui£_^UQUlQfi_jUM««M^M&JBB^flAMBHM^RSMflUil^Ati \*•**•!•••* */ •
32a. UV radiation administered at relatively low doses causes a depression
in local contact hypersensitivity (a fora of cell-mediated immunity)
-------
ES-39
resulting froa an inability to reapond to an ancigen presented
, through UV- irradiated skin.
32b. High doaaa of UV radiation cause a depression in systsaic contact son
delayed type hypersensitivity reactions, tbat reault in an inability
of tha aniaal to reapond to an antigen which is presented to the
tnirisl through "ffiTTi*Ha^*t akin.
32c.- Both the local and systeaic effecta on contact hypersensitivity are
aediated by a T suppressor cell which prevents tha developaent of
active laamilr/ to the ancigen.
32d. The iaaunosupprasaive effecta of ultraviolet radiation (UVR) have
been found to reaide alaoat entirely in the UV-B portion of the
ground level solar radiation.
33. SUPPRESSION Of THE TMMPHE SYSTEM MAY WAY AM TXPQgTAflT flffljj flf
(chapter 9).
33*. Aniaals which are* UV- irradiated develop T suppressor cells which
interfere with the iaaune reaponaa to UV- induced tuaors in such a waj
that the aniaala are aora susceptible to the growth of autochthonous
UV- induced tumors. The contribution of the suppression of the faenni
systea to cancer incidence that would reault froei ozone depletion is
reflected in the dose-response estimates of photocarcinogenesis
assuming that the action spectra for the two phenomena are the saae.
If these two iapacta have different action spectra, die estimates
could be either high or low.
34. LIMITED EigERIMESTAL DATA CTDICATE UV-B StTPPagSSES THg HDMAH IMMOSE SYSTEM
(chapter 9).
34a. Although tiiere is limited Information about the effects of UV
radiation on huaans, several studies indicate that the iaaune
response of huaans is depreaaed by UV radiation and is depressed in
UV-irradiated skin.
PITH ggcxpp TO MMiY HP1AH PISEASBS (chapter 9) .
3Sa. Freliadnary studies indicate that UV radiation aay prevent an
'effective iaaune response to aicro-organiaaa that infect via the
akin, thua predisposing to reexpreaaion or chronic infection.
35b. Two buaan diseaaea that aay be Inflnanrad by UV-B-induced iaaune
suppreasion are herpea virus infections and laiahaaniaais.
35c. Alaoat no research has bean conducted on tha influence of UV-B on
other infectious diseaaea; additional investigation ia clearly
warranted.
35d. For at leaat one theory of the aechanisaa of UV-B-induced suppression
of the-.iaaune systea (that involving urpcanic acid), a possibility
exists that non-whites, aa well aa whites, would be vulnerable to.
increased ianune suppression caused by ozone depletion. . _.
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ES-40
35e. Because UV-B can produce systemic immunologic change, the possibility
exists that changes in UV-B could have resulted in effects on
diseases whose control requires systemic rather than local immunity.
35f. Immunologic studies to date have not assessed the effects of long-
term, low-dose UV-B irradiation. Consequently, the magnitude of this
risk cannot be assessed.
36. EVIDENCE EXISTS SUGGESTING THAT CATARACT INCIDENCE PTTJ. CHAMCE PITH
ALTERATIONS IN THE FLUX OF UV-8 CAUSED KY OZONE DEPLETION (chapter 10).
36a. Many possible mechanisms exist for formation of cataracts. UV-B may
play an important role in
36b. Although the cornea and aqueous humor of the hmsn eye screen out
significant amounts of UV-A aad UV-B radiation, nearly 50 percent of
radiation at 320 am is transmitted to the lens. Transmittance
declines substantially below 320 am. so that less than 1 percent is
transmitted below approximately 290 to 300 nm. However, the results
of laboratory experiments on ««•«•»• indicate that short wavelength
UV-B (i.e., below 290 nm) is perhaps 250 times more effective than
long wavelength UV-B (i.e., 320 nm) in inducing cataracts.
36c. Human cataract prevalence varies with latitude and UV radiation;
brunescent nuclear cataracts show the strongest relationship.
37. INCREASES IH THE AMOUNT OF UV-> THAT fi^ BttAffH TffB fl^TTT^ APPEAR CAfAjm 9F
CAUSING STAftlJj MTINAL DISORDERS AMP RgTTNAL PKfmUKHATION. TBO CAUSES OF
BLINDNESS (chapter 10).
38. t-TMTTEQ STUDIES ANALYZING THE EFFECT Of TffCRBAStiP W"^ RADIATION OH CROPS
l VERSE IMPACTS . HQgEV OCLPSIONS ABOUT THE AMOUNT OF
YIELD LOSSES ATTBIBOTA»TJj] JO, PV-B CANNOT BE PttABN (chapter 11).
38a. Difficulties in experimental design, the large number of species and
eultivars, and complex interactions between plants and their
environment have prevented TffiB*l*lM*f'"* °* total crop loss from
in UV-B.
38b. Act^d spectra for UV damage to higher plants are limited, but
a strong weighting toward shorter UV-B wavelengths which are
affected by ozone reduction.
39. QF P^mT CPMTVARS TBSTKft Tff ^^ TABORATBBY. AypBonrrwLTKLy 70
PETESlCNEn TO BE SENSITIVE TO UV-Br CARg MIIST Kg TAIBT IH PffgBPBETIHC THIS
FINDING (chapter 11).
39a. Different eultivars within a species have exhibited different degrees
of UV-B sensitivity. While this suggests selective breeding could
limit damage, neither the basis for selectivity nor die potential
effect on other aspects of growth has been studied.
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ZS-41
39b. Laboratory experiments haw b««n shown to inadequately replicate
effects in to* field, thus the implications of eultivar sensitivity
ara not .certain.
39e. In some species, mitigation rosponsos sora raadily apparent in tha
field (a.g., increased production of DV absorbing flavonoids) have
reduced adverse impacts.
40. *n*g gypicrs OF ov-g BAPIATTQW HAVE im> gTAnrmirn «QP QML
MAJOR TlBMyF^jAj, ^QSYSTBUS AMP TOft OHLY A THTgP OF THE PTJLMT CRQBTH FOR]
(chapter
40a. Little or no data exist on enhanced 0V- B effects on trees, woody
shrubs, vines, or lower vascular plants.
41. LAgCg-PMCgRTAHrrTaS BCTST AS A ggSTTLT OF AH tMCTgCTCT BPgttMgHTAT. DESIGN
fflt_DQSIMET8y. RXJ.ST1JIC KXPKftJMPlTAL FIKLD PAUL SOOCKST A POTPfflAL
PtttfCTICH TH CSOF TTFT^ TOg s°*ff ff^ffff8 PP^ ^Q PIHAIICB> PV-B RADIATION
(chapter 11).
41a. Field experiments in which UV-B radiation has been supplemented are
limited. Several of the earlier field experiments are of limited
value since UV-B doses or other factors such as soil temperature vei
not sufficiently controlled or representative of field conditions.
Dose-response studies in the field are particularly different.
41b. The only long-term field studies of a crop involved soybeans. Th«s<
studies have found that enhanced levels of UV-B, simulating between
16 and 25 percent ozone depletion, caused crop yield reductions of v
to 25 percent in a particular eultivar. Smaller reductions in yielc
were experienced in years where drought conditions existed.
41c. Soybean (CV Essex) yield could be accurately predicted when total
UV-fi dose, daily i"*'"*?""* temperature, and number of.jtays of
precipitation were included in a regression model.
41d. The lipid and protein content «•£ soybean vas reduced up to 10
percent; however, higher UV-1 doses alone did not consistently resul
la the largest reductions.
41m. mie only several cultivars have been tested la die field, two out
•f three soybean cultivars tested under laboratory conditions were
sensitive to UV-B. If this relationship holds true in the field, it
suggests (when considered la light of yield reduction experiments)
that JJV-B increases could baza die potential of the world
agricultural system to produce soybeans.
42. THE gygKLTS OF flV-B OH PTOSAL Oft VHtAL PATBOCHIIS fA^Y wTTH ?ATHOCZH. PLANT
SMCTBS . AMD cnt3T7A^ (chapter 11) .
42a. Current evidence ee> possible interactions with pathogens is very
limited.
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ES-42
42b. Reduced vigor in UV- sensitive planes could render the planes more or
laaa susceptible to post or disaasa damage and thus result in changes
in crop yield.
43. CHAM2£S^^LJZ!LJLi.i^£££2£_Ii^C_iUiI2U£E_iiUuQ2^
(chapter 11).
43a. If enhanced UV-B favors weeds over crops, agricultural costs (e.g.,
for increased tilling and herbicide application) could increase.
However, .insufficient evidence exiats to form a basis for evaluating
this effect.
43b. Increases in UV-B could altar the results of the competition in
natural ecosystems and thus shift community composition. Since UV-B
changes would be both global and long term, possible UV- induced
alterations of plant species balances could result in large-scale
changes in the character and equilibrium of vegetation in
nonagricultural areas such as forests and grasslands.
44. DV-B RADIATION INHIBITS AM) STIMULATE* FLOW]{im4C . PEPEMPCTC OH THE SPBCIRfi
AMP GROWTH COHDTTIOSS (chapter 11).
44a. The timing of flowering may also be influenced by UV-B radiation, and
there is limited evidence that pollen may be susceptible to UV damage
upon germination.
44b. Reproductive structures enclosed within the ovary appear to be.
well-protected from UV-B radiation.
45. TMTERACnOHS BETUKEM PV-B RAPIAXIfff Miff ffiiH^*^ PiyTSiOMMBJfl!AL. FACTORS ARE
IMPORTANT IN DETERMINING PQTEHTIAL PV-B EFFECTS COS PLAHTS (chapter 11) .
45a. UV-B effects may be worsened under low light regimes or less apparent
under conditions of limited nutrients or water.
4Sb. Interactions with other environmental affects make extrapolation of
data from growth chambers or grsenheuees to field conditions
difficult ***** often unreliable.
45c. Thafflimtilnsil affect of higher UV-B and other environmental changes
eamfvt be adequately assessed by currant data, Extensive, long-term
stalls* would be required.
46. TMTTTAL ICTKgTMgHTS SHOP THAT
mTBAVTATJPr BABTATTOt RAW TJR POTSHTTAL TO HARM AQUATIC
PKSTffltS AMP Tflg UMITRD SCOPE OF THE
STUDIES PREVENT THE OPAMTTflCATIQH Of glSIEg (chaptar 12)-
46*. Increases in energy in the 290-320 nm wavelengths that would occur if
the ozone layer were depleted could harm aquatic life.
46b. Various experiments have shown that UV-B radiation damages fish
larvae and juveniles, shrimp larvae, crab larvae, copepods, and
plants essential to the marine food web.
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ES-43
46e. Op to some threshold level of exposure, most zooplankton show no
effect due to increased exposure to uV-B radiation. However,
exposure above tha dose threshold elicits significant and
irreversible physiological and behavioral effect*.
46d. While the exact limits of col<
been precisely determined, -as
variety of aquatic organisms
46«.
46 j
47.
48.
im and current exposure have not
of these two properties for a
to bo aaaantially equal.
Tha equality of tolerance and
radiation is currently an Important
* suggests that solar UV-B
ecological factor, and
tha sunlight-exposed organisms sacrifice potential resources to avoid
increased- UV-B exposure. Thus, even small increases of UV-B exposure
would be likely to further injure species currently under UV-B
stress.
46f. A decrease in column ozone is reasonably likely to diminish the time
that zooplankton can survive or broad at or near the surface of
waters they inhabit. For some zooplankton. the time they spend at or
near the surface is critical far breading, whether the population
could endure a significant shortening of surface time is unknown.
46g. Sublethal exposure of copepods produces a reduction in fecundity.
46h. Of the animals tested, no zooplankton possess « sensory mechanism for
directly detecting UV-B radiation; therefore, it would be unlikely
that they would actively avoid enhanced levels of exposure resulting
from a reduction in colt
461.
Exposure of a community to UV-B streaa in controlled experiments has
resulted in * decrease in species diversity, and therefore a possible
reduction in ecosystem resilience and flaxibility.
One experiment predicted an t percent annual loaa of the larval
anchovy population from a 9 percent reduction in column ozone in a
marina system with a 10-meter mixed layer.
ny py.g
BECAUSE
VARIABLE Al'l'lHUATTOM OF TTV.ft BADTATTflH TTt
48a.
XBE
saaaaa. (chapter 12) .
:ausa aquatic organisms are- mmall and do not ^ssually have fixed
locations, it is vary difficult to obtain accurate data needed to
modal the systems and verify results. ^Current maderstsnding of the
life cycle of organisms la vary
49. ABOPT OWE
OF THE gQRlP'S PRflTETl TS
MANY THTTIO WOBTJ5 eonNTRTBS THTS
PggrgHT
fi» TS
MSEARCH TS
TO IMPROVE OUR nWDERSTANnTHC OP HOB OTfiH* arVfxTTOH COOTJ)
SYSTEMS (chapter 12).
THESE
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ES-44
49a. A comprehensive analysis of sublethal and lethal effects of solar UV
on littoral, benthos, and planktonic ecosystems is needed.
49b. A model of energy flow analysis leading to protein production where
solar input ia augmented by increased ultraviolet radiation would be
required to better evaluate potential affects. Marine organisms
responses to projected increaaaa is UV must be considered in the
context of the «*ff?«n> as a dynamic moving fluid.
49c. Battar documentation of tha off acts of praaant levels of ultraviolet
light on marine organisms is
49d. Intensive research is needed to identify biochemical indict that
reflect UV stress in marine
(chapter 13).
SOa. Several commercial polymers (e.g., polyethylene, polypropyli
poly(vinylehloride)). although theoretically UV transparent, contain
chromophore impurities diet absorb light in the UV-B region of the
spectrum. Other polymers (e.g.. polycarbonate) have structural
features in their molecules that result in strong UV-B light
absorption.
50b. Several polymers have important outdoor applications (e.g., used in
siding and window glazing in the building industry, in film and
containers in packaging, in housewares and toys, and in paints and
protective coatings). Such polymers are likely to be exposed to
significant amounts of UV-B radiation. Other polymers are stored
outside before use and could deteriorate ****rHg these periods.
50c. Absorption of UV-B radiation in polymers causes photo-induced
reactions and altars important machsnicsl. physical, or optical
properties of the polymers (e.g., yellowing, brittleneas) and thus
degrade* (i.e.. reduce* the useful life of) the polymers.
51.
Sla. XsmVMaod amounts of stabilizers might adversely affect the
prooais!ii» «* «*• properties of some polymers
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ES-45
52. TMCREASZP Py-B BAPIATIQN DOE TO Q2ONF pfyy^XIOH COPID HAVE ADVERSE ECONOMIC
(chapter 13).
S2a. Changes in polymer processing properties can result in more equipment
shutdowns, higher maintenance coses, and increased utility casts.
52b. Increased operating costs and material coats (e.g., for stabilizers,
lubricants, and other additivea) vould have an adverse economic
impact on the polymer/plastic and related industries. -
52c. In a. case study using preliminary data and methods, and a given
scenario of ozone depletion (26% depletion by 2075), undiscountad
cumulative (1984-2075) economic damage for poly(vinylchloride) is
estimated at $4.7 billion (USA only). Due to the lack of data,
possible damage to other polymers hast not been aaaessed.
53. PqTEN'^IAL DAMAGES TO PQLVinrPg ymjrtirp TQ QZOHB PPLKTIOif *|fp
f^v. i)fyyrctnj TO gsriMATg (chapter 13).
S3a. Due to lack of relevant; experimental 4ata, only approxiaate
estimation •ethods are available to determine the potential extant of
light-induced damage to polymera and other materials.
53b. Depending upon the chemical nature of a polymer, the components of
«?h* compound, innj **«^ watfaerlog factors, frofb temperature
humidity tend to increase t±a rate of
53c. Research on dose-response relationahlps for polymers could increase
our ability to project the effecta of ozone depletion.
53d. Actual action spectra need to be developed for different polymers.
53e. The feasibility of different mitigation measures needs to be
experimentally determined.
53f. The synergistic effects of increaaed humidity and temperature need to
be considered. •. ».•• •
•***•
54a. According to these studies, increaaea in OV-B associated with ozone
depletion vould increase the quantity of ground-baaed ozone
associated with various hydrocarbon and nitrogen oxides emission
levels. Results for individual cities vary, denenrtl-ng on the city's
location and on the exact nature of the pollution.
54b. According to these studies, global warming would enhance the effects
of increased UV-B radiation on the formation of ground-baaed ozone.
54c. According to these studies, ground-based ozone would form closer to
urban centers;. This would cause larger populations in some cities to
be exposed to peak values. •> • — - -
-------
ES-46
54d. Mora raaaareh is needed to verify and axpaad the results of these
initial studies.
55.
TO DV.» BAPTATTMI
(chapter 14)
HYPRQGEH PgRffldPE BODLD MSPLT MOM TBCMAfi
55a. If hydrogen peroxide iaereaaes aa predicted la *Mf study,
oxidizing capability potantial of the atmosphere, including the
formation of acid rain, would be influenced.
55b. Mora research, especially a chamber study, is needed to -verify this
affect.
56.
TM CROnSP-flASgB QZOK1 O
ttYAT Iff At
(chapter 14).
If UV-B increases enhanced ozone production, more U.S. cities would
be unable to meet health-baaed ground-level ozone standards, and
background ozone would increase.
Crops, ecosystems, and materials would be adversely affected by
increased ground-level
56a.
56b.
57.
EVKNTUAT-^Y TffCRFASTTf6 'fm 3ATB AT HHTm priTJhP rr» «ugBT«i mnT r»
ICE THTO THE OCTAHS (chapter 15).
58.
AYBRA^ SEA UVEL APPEARS TO HAVE RISES 10 TO is oc vtun *t^ ~~-^*.
CEMTURY (chapter 15).
58a. Studies of the possible contribution of thermal expansion and alpine
meltwatar to sea level rise, baaed on the 0.6°C warming of the past
century, indicate that these two sources are insufficient to explain
the eatimated sea level rise Oat has occurred during this period. •
Consequently, some other source, such aa melting of the polar ice
caps, must be considered a poasibility.
59.
59a. According to published studies, tbarmal expansion of the oceans alone
would increase sea level rise between about 30 cm and 100 cm by 2100.
depending on the realized temperature change. This is the most
certain contribution.
59b. Melting of alpine glaciers sad possibly of ice on Greenland could
each contribute 10 to 30 cm through 2100, depending on the scenario.
This contribution also has a high degree of likelihood.
59e. The contribution of Antarctic deglaciation is
project. It has been estimated at between 0
possibilities cannot be ruled out that (1) i
•ore difficult to
100 cm; however, the
aaed snowfall could
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BS-47
lase the size of tho Antarctic lc» sheet and thereby partially
offset pare of the sea level riaa froa othar soureaa; or (2)
saltwater and .enhanced calving of tha lea shaet could incraaae che
contribution of Antarctic daglaciation to aa such aa 2 a. Tha
Antarctic contribution to aaa larval riaa aay be aore sensitive eo
tiaa delays after certain threshold conditions are reached than to
die aagnituda of total waraing.
60. OVER THE MUCH T/WCTP TKKM ^TffB inocT TKP cMTumm^ PTSTHTBSBATTON OF THE
BEST ANTARCTIC ICT MHiLgT MldBP RAISE SEA LKVC. _BY 6 JiKtEHS (chapter 15).
60a. If a disintegration tafcea place, glaciologists generally believe th
such a complete disintegration of the weat.Aatarctic ice sheet woul
take at leaat 300 years, sad probably at least 500 years.
60b. A global waraing might result ia sufficient thinning of the Ross an
Flleher-Ronae Ice Shelvea ia die next century to sake the process o
disintegration irreversible.
61 T/VMT. TRENDS IN SPBSTPdCB AMP BttKCCTCK iBIST BK APOED 08. SUBTRACTED^TO
cr/?BAL RISK ESTTMATKS Tlf QBPEft TO KTUJAT8 BBLATTVE SKA LZVEL RISE_AI
PARTICULAR LOCATIONS (chapter 15).
61a. Host of die Atlantic aad Gulf Coasts of die United States--as well
die Southern Pacific coast—are subsiding 10-20 ca per century.
61b. Louisiana is subsiding 1 a per century, while parts of Alaska are
emerging 10-150 cm per century.
61c. Due to subsidence already occurring ia areas such as Bangladesh,
Bangkok, and die Bile delta, dieae areas are extremely vulnerable t
aea level rise.
62. A SUBSTANTIAL RTSB Tit *)f^ Hnf^T- POPTJ PBMAingiTLY THIMPATE WETLANDS AND
^n TPA
TH8 SAT.TMtTY nv 'ESTUARIISS ejTO /^QPTy^ft^ (chapter 15).
62a. Louisiana is die scats aoatjwalaerable to a rise ia aaa level.
Important impacts would also fggor ia Florida, jfarylaad, Delaware,
•aw Jersey, and' ia dsa coastal regions of acher statea.
62b. A. rise ia sea level of 1 to 2 a by die year 2100 could destroy 50
percent to 80 percent of U.S. coastal wetlands.
62c. Limited studies predict daat increased salinity froa sea level rise
would convert cypress swaaps to open water aad dureatan drinking
water supplies ia areas such as Louisiana, Philadelphia, and New
Jersey. Other areas, such as Southern Florida, may also be
vulnerable but have not bean investigated.
62d. Studies of Bangladesh and die Rile Kiver Delta indicate th*c dxese
river deltas, which are already subsiding, would be greatly affects
by rising sea level, experiencing significant economic and
environmental losses. - ' "*'•-
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' - ES-48
63. EROSION PROJECTED IM VARIOUS STUDIES TO RESULT FROM ACCELERATE SEA
RISS CfflTLP THPEATES U.S. RECREATIOMAL BEACHES (ehaptar 15).
63a. Caaa atudias of baacfaas in Haw Jaraay, Maryland, California, South
Carolina, and Florida hava concluded that a 30-em riaa in saa laval
would result in beaches aroding 20-60 • or Jwara. .Major beach
preservation efforts would ba raquirad if racraational baachaa ara to
be maintained.
£A AfifiyT_lftt a\Tffft SCA. T-W^FBT^ ftYSC flOOZJD ^MGBSASZ TOT? ttaVmmCKS tltflM wff-flQpTjIlC TW
COASTAL AREAS (chapter 15).
64a. Flood damages would increase bacauaa highar water levels would
provide a highar base for stora aurgaa.
64b. Erosion would incraaaa die vulnerability to atorm waves, and
dacraaaed natural and artificial drainage would Increase flooding
during rainstorms.
65. ESTIMATES OF DAMAGE EKOH SEA TJtVg. ttTSK JgtST COMSlftiK TOSSI^^* MTTIGA.TIOH
BY HDMAN RZSPQHSgS (chap tar 15).
65a. Tha advarsa iapaeta of aaa larval riaa could ba awalioratad through
anticipatory land uaa planning and atructural daaign changaa.
65b. In a caaa study of two eitiaa, Charlaaton, South Carolina, and
Galvaston, Taxaa, acealaratad anticipatory planning waa aat'imatad to
raduca nat daaagas by 20 to 60 pareant*
66. ttglATBP TMPACTS OF A ClJPBAV gABMTWC BPPLP AI.SQ AVVRt.'!' IMPACTS OF SEA LEVEL
RISE (ehaptar 15).
66a. Ineraasad droughts might aoplify dia salinity ijapacts of aaa laval
riaa.
66b. Ineraasad hurricanaa and ineraaaad ratnf al 1 in coaatal araaa could
amplify flooding froai aaa laval riaa. ~
66c. Waraar tavparaturaa light iapair paat Jofiaation of salt warahaa and
weul^anabla •angrova awaapa to taka awar araaa that ara praaantly
aaltyprah.
66d. Dacraaaad nerdiaaatara wight raduca
67. RESEARCH OPPQRnnTTTIBS ECTST TO DtP80V15 SKA LKTEL tt.IS8 BSTIMAIliS AHD
IMPACTS (ehaptar 15).
67a. Tha wost critical araaa of raaaarch for Ta4nr1ng tha -variation in
aatimatas of fueara aaa laval riaa axa ica Malting and runoff in
Antarctica and Graanland and ica diacharga.
67b. Raaaareh in glacial diseharga in Antarctica ahould focus not just on
Vaat Antarctica, but on Piaa Island and East Antarctica.
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ES-49
67e. An improved program of tidal gauge station*, •specially in tha
southern hemisphere, and satellite altimatry should be used to
re saa level rise and the Bass balance of ice sheets.
68. CT-TMATE CHABCE HAS 'HAD A SICHIFICAHT IMPACT OH FORESTS HT THE PAST. IF
CURRENT PREDICTIONS WQWij ACgnttATg. Bggg IS A POTENTIAL FOR DRAMATIC
IH POBKSTS AND VKCKTA.TTOH OVUB ^ffi ^PtT TOO Y8ARS (chaster 16)•
68a. Climate models predict that a global •"^^ng of approximately 1.5°C
Co 4.5°C will be induced by a doubling of atmospheric 002 and other
trace gaaaa during tha next 50 Co 100 Tears. The period 18,000 to 0
year* B.P. is the only general analog for a global climate change of
this magnitude. The geological record from this glacial to
inter-glacial interval provide* a baaia far ^qualitatively
understanding how vegetation may ebanga in raaponaa to large climatic
ebanga.
68b. The paleovegetational rocord abova that climatic change as large aa
that expected to occur in raaponaa to C02 doubling is likely to
induce significant changes in cha eoaposition and patterns o£ the
world's bioaaa. Changes of 2°C to 4°C hare bean significant enough
to altar the composition of blames, and to eauae new biomes to appear
and others to disappear. At 18,000 B.P., the vegetation in eastern
North America was quite distinct from that of the present day. The
cold, dry climate of that time teems to have precluded the widespread
growth of birch. hemlorV, beech, alder, hornbeam, aah, elm, and
chestnut, all of which are fairly abundant in present-day deciduous
forest. Southern pinea were limited to grow with oak and hickory in
Florida.
68c. Available paleoecologieal and paleoclimatological records do not
provide an analog for the high rate of climate change and
unprecedented global warming predicted to occur over the next
century. Previous changes in vegetation have been associated with
climates that ware nearly 5°C £o 7°C cooler and took thousands of
years to evolve rather than rtejeiles, the time during which such
changes are now predicted to eoovr. Insufficient tempera! resolution
(e.g.. via radiocarbon dates) limits our ability to analyze the
deeadal-acale rates of change tfeat occurred vrior to the present
6S4.~ T.tmired experiments conducted with dynamic vegetation models for
•orth America suggest that deereaaea in net blomaaa may occur and
that significant changes- in species composition are likely.
Experiments with one model auggeat that eastern Berth American
biomass may be reduced by 11 megagrams per hectare (10% of live
biomaaa) given the equivalent of a doubled C02 environment. Plant
taza will respond individualiatically rather than aa whole
communities to regional changes in climate variables. At this time
such analyses must be treated aa only suggestive of the kinds of
4 Findings 68 to 71 are summarized from Appendix B, which provides a
comprehensive review of potential impacts of global climate change.
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ES-50
chang* that could occur. Many critical processes arc simplified or
oaittad and the actual situation could be versa or better.
68*. Future forest management decisions in major timber* growing ragions
ara likaly to ba affected by 'pfr^rfi'* in natural growing conditions.
For axample, ona study suggests that loblolly pin* populations ara
likaly to aova north and northaast into Pennsylvania and Bev Jersey,
while its rang* shrinks in tha wast. Tha total gaographic rang* of
tha spacias asy ineraaaa, but a net loss in produetiTity may result
baeausa of ahifts to lass aceaasibla sad lass -productive sitas.
Vhila tha axtant of such changes is unclear, adjustaents will ba
naadad in forest technology, resource allirestiop, planning, tree
breading programs, and decision-Baking to aaintain and increase
productivity.
68f. Dynsaic vegetation Bodela based on theoretical descriptions of all
factors that could influence plant growth must ba improved and/or
developed for all major kinds of vagatation. In order to make more
accurate future predictions, these models must ba validated using the
geological record and empirical ecological rasponse surfaces. In
particular, tha geological record can ba used to teat the ability of
vegetation Models to simulate vegetation that grew under climate
conditions unlike any of tha modern day conditions.
68g, Dynamic vagatation models should incorporate direct effects of
atmospheric C02 increases on plant growth and other air pollution
effects. Improved estimates of future regional climataa are also
required in order to make accurate predictions of future vegetation
changes.
69. T-TKT-nm Assasst^ffg gycCTsr THAT mpoBTMrr emmeies n> AcaTCPLTDRE AND FARM
PB.OPUCTTVITY. ARE LIKELY THBOOtSfflTf TSB ffOKTJ? Ty CTJUAJK OUMCS OCCURS AS
gsTTM*T^s (py IMPACTS OH spgg]7IC MSIQHS mfiK f>| fFlflf^T TO MAKE
AlTEBMATIVK SCUTARTQS (chapter 16) . -" --ev'*
69a. Climate has had a significant impaet'«n faxm productivity and
distribution of crops, fetamplaa include tttm 1983
«f^ gome fluted to a nearly 30 percent reduction in corn
la the U.S. ; tha persistent Great Plains drought between
1932-1937, which contributed to nearly 200,000 farm bankruptciaa; and
tie climate shift of tha Little-lea Age (1300-1800), which led to the
•handonmant of agricultural settlements in fr?i>tlmy| and Borway.
69b. World agriculture is likaly to undergo significant shifts if
traca-gaa-inducad climate warming in tha range of l.~3°C to 4.5°C
occurs over the next SO to 100 years. Climatic effects on
agriculture will extend from local to regional aad international
levels. However, modern agriculture is vary dynamic aad is
constantly responding to changea in production, marketing, and
government- programs.
69c. The main effects likaly to occur at tha field level will be physical
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ES-51
impacts of changes in thermal regimes, water eonditiona, and past
infestations. High tenperaturea have caused direct damage to crops
auch aa wheat and corn; moisture atraaa, often associated with
elevated temperatures,, is harmful to corn, soybean, and wheat during
flowering and grain fill; and increased pests are associated with
higher, •ore favorable temperatures.
69d. Ivan relatively snail increases in the mean temperature can inci
the probability of harmful effects in acme regions. Analysis of
hiatorical data has ahown that an incraaaa of 1.7°C (3°F) in mean
temperature changes by about a factor of three the likelihood of a
five-consecutive-day maartmnm temperature event of at laaat 35°C .
(9S°P) occurring in a city like Dee Moines. Xa regions where crops
are grown eloae to their maTlmna tolerance limits, extreme
temperature events may nave aignif icant barmful ef fecta on crop
growth and yield.
69e. Limited axperimenta using climate scenarios and agricultural
productivity models have demonstrated the sensitivity of agricultural
systems to climate change. Future farm yields are likely to be
affected by climate because of changes in the length of the growing
season, heating units, extreme winter temperatures, precipitation,
and evaporative «I*M«MI-. In addition, field evaluations show that
total productivity is a function of the drought tolerance of the land
and the moisture reserve, the availability of land, the ability of
farmers to shift to different crops, and other factors.
69f . The transition costs associated with adjusting to global climatic
change are not easily calculated, but are likely to be very, large .
Accommodating to climate change may require ahifting to new lands and
crops, creating support aarvieaa and induatriea, improving and
relocating irrigation systems, developing naw soil management and
peat control programs, and breeding and introducing new heat* or
drought •tolerant species. The consequences of these decisions on the
total quantity, quality, and coat of food are difficult to predict.
69g. Current projections of the effects of climate change on agriculture
are limited because of uncertainties in predicting local temperature
and precipitation pattar&a talma; -global climate models, and because
of the need for improved reaearch atudies uaing controlled
atmoapherec, statiatieal regreaaion modela, dynamic crop models and
integrated modeling approachea.
70. H&TZB^ RESOURCE SYSTEMS HAVE PitPRBQQHP IMPORTANT CHARGES AS THE EARTH'S
CLIMATE HAS SHIFTED TH Tfflt PAST. CPMBMT AHAI.YSKS BfflPSST AH 1NTENST"PTTT>
jf CT.TMATR eHAnen oeenftfi AS gftKPTCTED (chapter 16).
70a. There is evidence that climate change aince the laat ice age (18,000
years B.P.) has significantly altered the location of lakes --
although tiie extant of preaent day lakes is broadly comparable with
18,000 years B.P. For example, there is evidence indicating the
existence of many tropical lakes and swamps in the Sahara, Arabian,
and Thor Deserts around 9,000 to 8,000 yeara B.P.
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ES-52
70b. Tho inextricable linkages between tha water cycle and climate ensure
that potential future climate change will significantly alter
hydrologic processes throughout tha world. All natural hydrologic
processes --precipitation, infiltration, storage and movement of soil
moisture, surface and subsurface runoff, recharge of groundwater, and
evapotranspiration— will be affeetad if climate changes,
70c. As a result of changes in key hydrologic variables such as
precipitation, evaporation, soil •oisture, and runoff, cliaata change
ia expected to have significant affects on water availability. Early
hydrologie Impact studies provide evidence that relatively small
changes in precipitation and evaporation patterns might result in
significant, perhaps critical, changes in water availability. For
many aspects of water resources, including human consumption,
agricultural water supply, flooding and drought management,
groundwater use and recharge, and reservoir design and operation,
these hydrologic changes will have serious Implications.
70d. Despite significant differences among climate change scenarios, a
consistent finding among hydrologic Impact studies is the prediction
of a reduction in summer soil moisture and changes in the timing and
magnitude of runoff. Vintar runoff is expected to Increase and
summer runoff to decrease. These results appear to be robust across
a range of climate change scenarios.
70e. Future directions for research and analyses suggest that Improved
estimates of climate variables are needed from large-scale climate
models; innovative techniques are needed for regional assessments;
increased numbers of assessments are necessary to broaden our
knowledge of effects on different users; and increased analyses of
the impacts of changes in water resources on the economy and society
are necessary.
71. MORBIDITY AKP MQRTAt^TTY RATES ARE ASSQCTATKP fflTP PEA.THBB ETTMjflgg m OUR
SOCIETY (chapter 16).
71*. Weather has a profound affect on hmman health and wall being. It has
been demonstrated that weather is assort arid with changes ia birth
races, outbreaks of pneumonia, iaflmawca, and bronchitis, and related
to other morbidity effects, and is linked to pollen concentrations
and high pollution levels.
Tib. Large increases la mortality have occurred, during previous heat and
cold waves. It is estimated that 1,327 fsrsllrlas occurred la the
United States as a result of tha 1980 heat wave, and Missouri alone
accounted for over 25 percent of that total.
71c. Hot weather extremes appear to have a more substantial Impact on
mortality than cold.wave episodes.
Tld. Threshold temperaturea, which represent marl mum and minimum
temperatures associated with Increases in total mortality, have beexv.
determined for varioua cities. These threshold temperatures vary
regionally; for example, the threshold temperature for winter
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ES-S3
mortality IB mild southern cities such a* Atlanta is 0°C and for more
northerly cities such as Philadelphia, threshold temperature is -5°C.
71*. If future global warning induced by increased concentrations of trace
gases does occur, it has the potential to affect human Mortality
significantly. In one study, total summertime mortality in New York
City was estimated to increase by over 3,200 deaths per year for a
7°F trsce-gas-induced warming without acclimatization. Zf Bew
Yorkers fully acclimatize, the number of adrtiffmial deaths is
estimated to be no different than today. It is hypothesized that if
climate warming occurs, some additional deaths are likely .to occur
because' economic conditions and the basic infrastructure of the city
will prohibit full acclimatization even if behavior change*,
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ES-S4
QOAHriTATTVE ASSESSOR! OF KXSXS HTH XHIB3AZID MODEL
AS INTEGRATED ASSESSMENT Ot5 TOR VARIOUS SCENARIOS OF
SUBSTANCES SHOWS THAT HARM DEPENDS OW THE ^fl**^ Of THE gROPDCTIOK OF
AND BRQMINE . B^tlNC SOTSTANCEg.
Risks ara avalxsatad by using Cha intagratad aodal to aiaulata tha impact of
"what -if" scenarios of production of ozona-daplating substancas and scenarios of
othar trace gas concentrations on tha ataosphara and on huaan health and tha
environaent. Sensitivity analyses of alternative assuaptions are also
conducted.
Analysis of tha results of all tha scenarios indicates that adverse iapacts
on health and welfare are lowered with reductions in tha production of ozone*
depleting substances.
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ES-55
72. ttopiyrcATTos OF THE TRACE CAS coaposinQK OF THE ATMOSPHERE CAN BE
TO ALTBt COMIC? Q2QHE ABUHDAHCfi (chapter 18).
72a. The range of global average total coluan ozone change projected for
the year 2075 baaed on a paraaeterized representation of a
one-diaensional aodel could vary froa as high as over 50 percent
depletion, for a case where global use of chlorine aad broalne
bearing aubataacea grows at aa average *wvfl rate of 2.8 percent
froa 1985 to 2100 (5.0 pereeat pax year froa 1985 to 2030, followed
by no growth through 2100), to increased abundance of ozone of
approxiaataly 3 percent, for a ease where global use of chlorine aad
broaine hearing substances declines to 20 pereeat of its 1985 value
by 2010. Exhibit ES-6 displays the global ozone change estiaates
for these two scenarios, aa well aa estiaates for four aeenarioe in
between; the aix "what if* scenarios eraainad include:
RffaCtlPTT Vaa of chlorina aad bromina baaring aubataaeaa
daeliaaa to 20 pareaat of ita 1985 valua by 2010, aad ramaiaa
thereafter, yialdiag approxiaataly 3.0 percent increased
abundance by 2075;
Bo Crovefa; no growth in uae of chlorina aad broadna •bearing
aubataneea froa 1985 to 2100, yielding approxiaately 0.3 percent
iaereaaed ozone abundance >y .2075;
l.gt firowch; 1.2 percent growth froa 1985 to 2050, followed by
no growth, yielding approziaataly 4.5 percent depletion by 2075;
2.S» Croveh; 2.5 percent growth froa 1985 to 2050, followed by
no growth, yielding approxiaataly 25 percent depletion by 2075;
3.8% Crovgh: 3.8 percent growth froa 1985 to 2050, followed by
no growth, yielding over 50 percent depletion by 2075;
3.0* Growth: 5.0 percent growth froa 1985 to 2050, followed by
no growth, yielding over 50 percent depletion by 2075.
The trace gaa concentration aaaoaptions uaed in theae aix eases are:
C02 — HAS 50th percentile; CB4 -.-.0.017 ppa per yaar (approxiaataly
1 percent of current CH4 concentration); aad H20 — 0.20 percent par
72b. Current data are not sufficient for distinguishing whether CB4
concentrations are likely to increase in a linear manner (e.g. at
0.017 ppa per year, or approxiaataly 1 pareaat of currant
concentrations) or in a coapound aaaner (e.g., at 1 pareeat par year.
coapouaded annually). The sensitivity of the ozone change esdaatas
in 2075 was evaluated for the following aix aaauaptiona regarding
future CH4 concentrations:
o Seansrio A! coapound annual growth of 1 percent froa 1985 to
2010, followed by constant concentrations at 2.23 ppa;
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ES-56
OF GLOBAL OZOB 9BUZXOB XI 2075
FOR. SIX CASES OP CIC QSB
10
•10
OzanaCtMnaa
•20
•SO
•40
•40
•raw* 12S U»
•raatamMftMftaaatatton
Uaing a paraaMtarizad rapraaantation of a ona-diaanaional Bodal, tha
potantial changa in ozona waa avaluatad for aiz acanarioa: 80% Raduction:
global CFC uaa daclinaa to 20 parcant of currant larval* by 2010, and raaains
constant tharaaftar; No Growth: no growth in CFC uaa froa currant lavals; 1.2%
Growth: 1.2 parcant growth fro* 1985 to 2050, followad by no growth; 2.5%
Growth: 2.5 parcant growth froai 1985 to 7050, followad by no growth; 3.8%
Growth 3.8 parcant growth froai 1985 to 2050, followad by no growth; 5.0% Growth:
5.0 parcant growth froai 1985 to 2050. *«*§jfe by no growth through 2100). Tha
p**imi ***i«>eiona uaadlS^Baaa aiac caaaa ara: C02: HAS 50th
par cant ila; CB4: 0.017 ppa par yaar (approxliiataly 1 parcant of currant CH4
concantratioa); and H20: 0.20 parcant par yaar.
Currant 1-D aodala aecurataly raflact global daplation; Antarctic oxona
hola haa no lapaet on global oxona laval*.
latad
Graanhouaa gasaa that countar daplation grow at hiatorically-axtr
rataa.
Growth rataa for ozona daplation ara for global aaiaaiona; it ia aaauoad
that aaisaiona do not incraaaa aftar 2050.
Ozona daplation lioitad to 50 parcant.
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ES-57
o Seanario B: linaar growth at 0.01275 ppa par yaar (75 pareant of
tfaa 0.017 ppa growth);
o geanmrlo C: linear growth of 0.017 ppa par yaar (approxiaataly 1
parcant of currant concentrations);
o pe«M*-La P; linear growth at 0.02125 ppa par year (125 parcant
of tha 0.017 ppa growth);
0 geanario E: coapouad «mn«l growth of 1 pareant;
« $fifBICi&_£: eoapouad aimnsT growth of 1 percent froa 1985 to
2020, growing to 1.5 parcant i"*ar*iimf •«"""1 growth by 2050 and
For tha 2.5% Growth aeenario, the astlaeta of ocone daplation by 2075
rangaa from about 14 parcant (Scenario F) to 30 pareant (Scanario A)
acroaa tha*a six CB4 assuaptiona evaluated. Exhibit ES-7 displays •
tha results for these six CB4 asauBpcions. Aa ahown in tha axhibit,
dia diffaranea batwaaa tha 1 pareant linaar (0.017 ppa par yaar) and
1 parcant coapoundad aaauaptioaa (Scanarioa C and E) i* approxiaataly
6 parcant daplation. Thia aancitivlQr of tiia ozoaa daplation
aatiaata* to tha aacuaption about linaar Taraua coapound growth of
CHA eoncantrations ia auch largar than tha aansitivity to tha ranga
of aaauaptiona rxaninad ragarding futura 002 concantrationc (froa tha
25th to tha 75th pareaatila HAS aatiaataa) and ragarding futura N20
eoncantrations (froa 0.15 parcant simusl coapound growth to 0.25
pareant annual coapound growth).
73. TOP.PTKRttSTOHAL (g.p) MOPgTS fmTOTgT Cyg***'*g AYfflA'jfP GLOBAL PCTTBTIOS THAU
OffE-PTMEHSTQKAL fl»g> MffgE^S- 2-P *ataa&_L1SR WlgPTgy THAT Q70KK DEPLETIC»I
cm. Bteggp THE GLOBAL AVERAGE AT HTCH IATITPPES A»» *« TJ!!g5 TB/tfT THfi
GLOBAL AVgRACE AT THE EQUATOR (chaptar 18).
73a. For a eaaa of 3 pareant *^"**1 growtii in aaiaaions of CFCs, no
oaiaaions of Halons, and incraaaas in traea gaaaa of: C02 --
approxiaataly 0.6 pareant par yaar; CB4 •• 1 pareaat par yaar; and
K20 •• 0.25 pareant par yaar, a 2-D aodal aatiaataa approxiaataly 5.A
pareaat global avaraga 4aplatioa*ftgr 2030. For tha aaaa aeanario of
tmm fwitfwyfff^tfi . t**^ paraaatarizad
Representation of a 1-D aodal aatiaataa only 3.0 pareant daplation by
•1030.
73b. For thia aaaa eaaa of aaia'sions aad trace gaa eoncantrations, tha 2-D
aodal eatiaataa of ocoaa daplation in 2030 at high latitudes are
approxiaataly; 60°H — 8.7 pareaat; and 50°I — 7.0 pareant.
74. KSTTMATKfi nv MMPSPHEPTe MOPTTTCATIOW. ffltTK CAHCTB CASKS AHT) PEATHS.
fiATAPAfT ftWVC MATVPTATC 1\AltA CTfMLAT
an TOT; BATE AT WHICH OZONE-DEPICTING CAS*S CRffffi A*n
-------
ES-58
EXHIBIT ES-7
01 2075
no
•10
•20
•so
Using a paraaotorizod representation of a one-dimensional model, the
potential change in ozone vas evaluated for aix aasuBptions about future aethane
concentration: Seenaiflp ^: compound annual growth of 1 percent from 1985 to
2010, followed by constant concentrations at 2.23 pper, gfitTTflTlf* ft* linear growth
at 0.01275 ppm per year (75 percent of the 0.017 ppm growth); Scenario C: linear
growth of 0.017 ppm per year (approximately 1 percent of current
concentrations); fr^jnario Pi linear growth at 0.02125 ppm per year (125 percent
of the 0.017 ppa growth); s«t«Mrta E: compound annual growth of 1 percent; and
: compound annual growth of 1 percent fro» 1985 to 2020. growing to
1.5 percent compound annual growth by 2050 and thereafter.
All estimates based on the 2.5% Growth
growth from 1985 to 2050, followed by no
gas assumptions used in these cases arm: 002:
percent growth per year.
•rio 1985 to 2100 (2.5 percent
thereafter). The other trace
•AS 50th percentile; and H20: 0.20
Current 1-0 models accurately reflect global depletion; Antarctic ozone
hole has no impact on global ozone levels.
.. Greenhouse gases that counter depletion grow at historically-extrapolated
*»tes.
- Growth rates for ozone depletion are for global emissions; it is as
that emissions do not increase after 2050.
Ozone depletion limited to 50 percent.
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ES-59
74*. The models used in this risk assessment assume that Antarctic ozone
depletion haa no global implications and that global trends do not
invalidate estimates of current models.
74b. Except as noted, projected effects assume that: greenhouse gases grow
at historical rates indefinitely; current one-dimensional models
accurately project depletion; production of ozone deplaters does not
grow after 2050; ozone depletion is Hsrffad «o 50 percent; the action
spectrum causing skin cancers is OKI; sad the temperature sensitivity
of the earth to doubled C02 is 3°C.
74c. In 2100, projections of ozone depletion range from over SO percent
for the 5% Growth scenario (ozone depletion is constrained at 50
percent in this analysis) to 47 percent for the 2.5% Growth scenario
to an increase in column ozone abundance of marly 5 percent for the
80% Reduction scenario.
74d. For cohorts born before 2075, the number of additional nonmelanoma
skin cancers projected ranges from a 261.5 million increase for the*
5% Growth scenario to a 115 million increase for the 2.5% Growth
scenario to a reduction of 6.5 million skin cancers for the scenario
of 80% Reduction in all ozone depletars,
74e. For cohorts born before 2075, the increase in total melanoma eases
ranges from a 1.3 million case increase for the 5% Growth scenario to
a 609,000 increase for the 2.5% Growth scenario to 54,000 fewer cases
for the scenario of an 80% Reduction in all ezoae depleters.
74f. For cohorts born before 2075, total mortality from melanoma and
nonmelanoma ranges from a 5.6 million increase for the 5% Growth
scenario to a 2.4 million increase for the 2.5% Growth scenario to
115,000 fewer cases for the scenario of 80% Reduction in all ozone
depleters.
74g. For cohorts born before 2075, the increase in total cataract cases
ranges from 26 million for the 5% Growth scenario to 15.1 million for
the 2.5% Growth acenario to 9,500 for the scenario of 80% Reduction
in ozone depleters.
74h. The rise in global temperature W-.J075 rangea from U.6°C in the 5%
Growth acenario to 5.6°C in the^5* Growth scenario:co 4°C in thai
scenario of 80% Reduction in all ozone depletars.
74i. Impacts are also projected for ot&er areaa such aa aaa .level rise.
ground-baaed ozone. Materials, aquatics, sad aoybean yield.
75. ODAMT1TATIVE ESTIMATES OP BISKS VMEY wTTH ASSIBgTTOWS ABOOT FPTDRE
gMISSTOMS QP CttgEHUOPSE CASES THAT PTTJ. COSffBTinTg TO GLOBAL gARMTBC
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BS-60
75b. If future deeiaionmakars limit the concentrations of C02, H20, and
CB4 to prevent global warming from exceeding 2°C (±50%) in 2075, thay
would by -necessity have to li»it growth of ozona daplatars to tha No
Growth case; for'other eaaas increases in ozona daplatara would ba
too largo to achieve that objective.
75c. Ozona daplation aaaoelatad with tha Bo Growth or 1.2% Growth
scenarios iaoraaaaa naarly 3 to 5 pareant if global warming ia
limited to 3°C (±50%); akin eanear deaths would increase 43 pareant
' for.paopla alive today. v •
7Sd. Estimates of T*****"* •^••f»«^ ara inherently uncertain even without
consideration of futura policy daciaiona and could affact
quantitative riak eatimataa.
76. QPANT1TATTVE ESTIMATES Of RTSK VMBT BTTB"t!WJC*JTATMTT ABflOyPOSE-pJESPOlTSE
coEFFTcimrrs. Adirion SPECTRUM- IJKTTS of QZONK PEPUTTQH. AHP
BE5POJf5IVP^^^ OF MOPET^ TO ATitos^tBS^c PRPLBTTOR (chanter 18)
76a. For people aliva today and born bafora 2075, additional skin cancer
eases would be reduced 45 pareant if one assumes the lower dose*
response coefficients that are one standard arror below the best
estimate and 66 percent higher if ona assumes the higher coefficients
that are one standard arror above the beat estimate.
76b. For people alive today sad born bafora 2075, additional skin cancer
cases would ba raducad 11 percent if the Erythema action spectrum,
rather than tha DHA, action spectrum, ware used to measure health
effects.
76c. Limiting projected daplation to 50 pareant from what the
parameterized 1-D model would project reduces projected deaths for
later cohorts. For people born from 2030 to 2074, limiting depletion
to 50 percent reduces deaths by 13 percent for tha 2.5% Growth
scenario and 66 pareant for tha 5% Growth scenario.
76d. For people alive today and born'Before 2075, akin cancer cases would
be reduced 62 percent in the 2.5% Growth scenario if the atmosphere
wars lass sensitive to potential jeVtioa daplatars (using the 10th
pereantila)» and increased 54 paromut If tha. atmosphere wore
sensitive (using the 90th parcenrflbe). -
**- MAPK AT TWTS TTMK. CASK SRSHPI MSOLTS
. PAMACg. MiP LOSS OF C80F TULfl /MKB PMSCTK (chapte
18).
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ES-61
OF ms ISSUE
A number of prior assessments of atratoapharie modification and climate
change have bean dona. A partial liat with daaeriptiona is ineludad balow:
1. National Academy of Sciences (HAS). 1975. 1976. 1979. 1982. 1983
Several assessments of anthropogenic influaneea on the stratospheric ozone
layer were coordinated by the National Academy of Sciences. The first report,
in 1975, focused-on the effects of propoaed floats of supersonic transports on
the stratosphere.- Subsequent reports focused OB ehlorofluorocarbons.
2. National Aeronautics and Spaee Administration (NASA), 1977. 1986
NASA has convened several technical panela to review models and chemistry.
In addition, it completed a scientific assessment in 1986.
3. Vorld Meteorological Organization.
National Aeronautics and Spaea Administration,
Federal Aviation Administration,
National Oceanic and Atmospheric Administration,
United Nations Environment Programme,
Commiaaion of the European Communities, and
Bundeministerium fur Forschung und Technologic
International assessments of the stratosphere have been conducted by the
European Community, the United Kingdom's Department of the Environment (1979),
and by the United Nations Environment Coordinating Committee on the Ozone Layer
(1981, 1984, 1986).
The most recent and most ambitious assessment of the scientific issues
regarding the stratosphere was coordinated by the Vorld Meteorological
Organization with the assistance of several other organizations. Approximately
150 of the world'a leading scientists participated in this assessment.
1. Climatic Impact Aaaeasment Program. 1974
Initial concern over anthropogenic influences on the climate and the
stratospheric ozone layer lad in 1971 to the establishment of the Climatic
Impact Assessment Program (CIAP). Coordinated by the Department of
Transportation, CIAP's objective waa to aaaeaa, by a report in 1974. the Impacts
of climatic changes duo to projected fleeta of supersonic transports.
2. National Academy of Sciences: 1979, 1982, 1983
Three panels were convened by the National Academy of Sciences to aaaeas the
scientific basis and certainty of the effecta of carbon dioxide concentrations
on global climate. Reports ware raleaaad in 1979., 1982. and 1983.
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KS-62
3. tforld Matarological Organization,
International Council of Scientific Unions, .sad
Unitad Rations Emrironaant
Efforts to aehisva an iatarnational scientific eoasonsus oa carbon dioxide,
trac* gasea, and cliaata war* eoordiaatad by the World Hatarological
Organization (WO), TTH*^n^y1
-------
ES-63
Commission of th« European Communities, (1981), Evalnatier^ of the Effaces of
ChlaraflAiefaearpotia on Ataoapheri.e Ozene ! Pf eaeat S**a
Brussels , Belgium.
Department of the Environment, (1979),
'
if f •t on
Ozone. Pollution Paper No. 15, Central Directorate of
Environmental Pollution, Department of the Environment, London, 'U.K.
EPA Science Advisory Board, (March 1987), Review of EPA 'a An Aaaeaa»eng of the
Rlaka of Stratospheric Madtfteatloy. prepared by EPA'S Science Advisory
Board, Washington, D.C.. SAB-EC- 87-025.
Crobecker, A.J., S.C. Coroniti, and R.H. Cannon. Jr., (1974), Keoort of
Findings. The Effects o^ Strataapherie Pollution bv Aircraft.
DOT-TST-75-50, prepared by the Department of Transportation Climatic Impact
Assessment Program, Washington, DC. •
Hoffman, J.S. (1986), "The Importance of Knowing Sooner," in J.C. Titus (ed.),
Overview. U.S. Environmental Protection Agency, Washington, DC.
Hunter, J.R. , S.E. Kaupp, and J.H. Taylor. (1982), •Assessment of Effects of
Radiation on Marine Fish Larvae," in J. Collins (ed.), The ttola of Solar
Ultraviolet Radiation in Marine Keosvsteaa. pp 459*497, Plenum, Hev York.
National Academy of Sciences (HAS), (1979), Carbon Pieride mA Q|p^fy; A.
Scientific As«e«siMflt. National Academy of Sciences, Washington, DC.
NAS (1982), Carbon Dioxide and Cliaatei A Second Asse««»en1^. National Academy
of Sciences, Washington, DC.
NAS (1983), Changing
nf
IMnvfil* &*•*«•
fifiejBi££ee., National Academy of Sciences, Washington, DC.
NAS (1976), H*T«^»»^»ona; Effeeta on Stratnaphgrte Qgone. HAS, Washington, DC.
HAS (1979), PrefcaeCion Ayainat Depletion of StraCoaaharte Qgena bv
Chlorofltiaraftarfao|ia. NAS, Washington, DC.
NAS (1979), Stragaapherie Ozone Dealetiatt by Tial ftearbona;
NAS, Washington, DC.
Effects of Stratoanhairle Oeone ftaduerdi
NAS (1982) ,
NAS, Washington, DC.
NAS (1984), Cauaes and Effect^ of Changea in Stratosphgrie Qzt
NAS, Washington, DC.
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ES-64
National Aeronautics and Space Administration (RASA) (1977),
ChlorofluoroiMthanea and, the Stratosphere. RASA Reference Publication 1010
RASA. Washington, DC.
RASA (1986), Freaanc State of Knowladfa of th» Pppag Aea
. NASA Reference Publication 1162, HASA, Washington, DC.
Seotto, J. (1986), •Hon*slanoaa Skin Cancar - TJV-B Iff acts," in J.G. Titus
(ad.) Z{f&ct.3 of Changes in Stratoan^**TJ.c Qgat>* *ftd Clohal. CllMattti Voli
2: Stratospheric Ozone. U.S. Environmental Protection Agency, Washington.
DC.
Sarafino. G. and J. Frederick (1986), •Global Modeling of the Ultraviolet Solar
Flux Incident on the Biosphere,* prepared for the U.S. Environmental
Protection Agency.
United Nations Environment Programme, UHEP (1984), gnviTa**M«e*l Aaaaasagne of
Ozone Laver Depletion and its Impact as of October 198A. Coordinating
Committee on the Ozone Layer (CCOL), UHEP.
UHEP (1986), draft report of the CCOL meeting, 1986.
World Meteorological Organization (1979), gfpftyt of the Pir«g Seagion of the CAS
WorVei.Tig Group or> ^P>oyph*ri-c Carbon Ptori^* WHO Project on Rssaarch
Monitoring of Atmospheric C02, Aep. No. 2, Coewission for Atmospheric
Sciences, WHO, Geneva, Switzerland.
ling Staff, WHO,
WHO (1981), Joint VMQAK
of C02 on Gliaao Variations and their laoaet. Joint
Geneva, Switzerland.
WHO (198S), Report of the InternagJOBal Ca^rfaranea on the Asaegaaent of the Role
of Carbon Ptmcld* and of ofchor Cr*anhati«a ^"SlI in CH«ag« TJ»fl*tlem* and
Aaaoeiaired lapaeta. WMO-Ro. 661, WMO/ICSU/UflEP, WHO, Geneva, Switzerland.
WHO (1986).
fikmnf* TOD Global Ozone
Research
Mont
oring Project — ftaporc Bfa. 16, WO, Geneva, Switzerland.
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ES-65
TABLE OF
PAGE
I
ACKNOWLEDGMENTS i
ORGANIZATION ES-1
INTRODUCTION ...*. * ES-2
SUMMARY FINDINGS \ ES-5
CHANGES IN ATMOSPHERIC COMPOSITION ES-I5
POTENTIAL CHANGES IN 02OHE AND CLIMATE ES-23
HUMAN HEALTH, WELFARE, AND ENVBtONHENTAL EFFECTS ES-32
QUANTITATIVE ASSESSMENT OF RISKS WITH INTEGRATED MODEL ES-5*
VOUME II
fifyyfrsftfntxvMVMTK [[[ i
INTRODUCTION . I
The Rise of Concern About Stratospheric Change 1
Concern About Public Health and Welfare Effects of Global
Atmospheric Change 1
Need for Assessaents 2
1. GOALS AND APPROACH OF THIS RISK ASSESSMENT 1-1
Analytic Framework 1-1
Supporting Docuaents and Analysis for this Review 1-2
Chapter Outlines 1-2
2. STRATOSPHERIC PERTORBARTS: PAST CHABdS HI CONCENTRATIONS
J0D FACTORS THAT DETERMINE COBCimiSZQKS 2-1
.'. 2-1
Findings 2-3
Measured Increases la Tropospberic Concentrations of
Potential Ozone Depleters 2-4
Measured Increases in Tropospheric Concentrations of
Potential Ozone Increasers 2-13
Factors that Influence Trace Gas Lifetimes 2-21
Long-Lived Trace Gases 2-22
Trace Gases with Shorter Lifetimes . 2-26
Carbon Dioxide and the Carbon Cycle 2-26
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SS-66
TABLE OF COBUBTS
PAGE
Appendix A: -CFC Emissions-Concentrations Model 2-28
Reference* ...; ....... ]"!!!!!!! 2-30
3. EMISSIONS OF INDUSTRIAIIX PRODUCED POTENTIAL OZONE MODIFIERS 3-1
3-1
.
Introduction .... ............ . ..... . ..... . ....... ~. ........ m ....... 3..$
Chlorofluorocarbon* ............. . ............... !!!!!!!!!!"!!-!!! 3-6
Chlorocarbon* ..... , ..... ...... ......... ... ..... . ...... !!!!!!!!!!! 3-58
Haion* — '. .................................. I!!!IIII'II!!!I!!!!!! 3-59
Reference* .................... .... .
Appendix A: Ch«aic*l T3»m E*ti»»tc Had* Av*il»bl«
Sine* Publication of ta* &i«k A«M«aMnt ................. A-l
Appendix At Reference* ......... ................................. A- 10
«•»
4. FUTURE EMISSIONS AND CONCENTRATIONS OF TRACE GASES HITH
PARTLY BIOCENIC SOURCES ...................................... 4-1
Suanery ; 4.^
Findings f 4.2
The Influence of Trace G«se< on the Stratosphere and
Troposphere 4.4
Trace Gas Scenarios 4.4
Effects of Possible Future Lisdts on Global Warming 4-23
Conclusion 4-23
References 4-25
5. ASSESSMENT OF THE RISK OF OZONE MODIFICATION 5-1
S«*»*ry 5-1
Findings .". .».. 5O
Introduction 5.5
Equilibriua Prediction* for Tiro-Di»en*ion*l Model* 5-18
Time Dependent Prediction* for Ooe-DlMnslonal
Model* for Different Scenario* of Trace Ca*e* 5-32
Dependent Prediction* for Tvo-Dlaoa«io«al Model*
with Different Scenario* of Trace Ca*e* 5-40
Model* Fail to Represent All Processes That Govern
Stratospheric Change la * Coaaloto end Accurate Manner 5-61
The Implication* of Ozone Monitoring for /H««+tttlng Risk*
of Ozone Modification 5-80
Reference* 5.104
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ES-67
FACE
zzz
6. CLIMATE ........... ; ...... '. ............... . ....................... 6-1
-1
Findings
The Greenhouse Theory
Radiative Forcing by Increases in Greenhouse Casea
Ultisiate Temperature Sensitivity
The Timing of Global Baning
igional Changes in Climate Due to Global Wanting
1 • •
•15
r!8
-22
Effects on the Stratosphere of Possible Control of
Gases ...................... .... ..... ............... ...........
6-26
Attachment A: Description of Model to be Used in Integrating
Chapter .................... . ..... . .................
6-28
Attachment B: Trace Gas Scenarios ................................ 6-32
References .................... . . . . .............. ... ..... ......... 6-33
7. RONMELANOMA SKIN TUMORS . . . ............... . ....................... 7-1
Suanary .................... . ................................. .... 7-1
Findings [[[ 7-2
Background on Solar Radiation and the Concept of Dose ............ 7-5
Introduction .................................. ..... . ............. 7-5
Biology of Nonmelanoma Skin Tumors : Links to UV-B ................ 7-11
Epideaiological Evidence . ........................ . ............... 7-27
Dose-Response Relationships ...................................... 7-40
Attachment A ....................... ............................... 7-49
References [[[ 7-58
8. CUTANEOUS MAUGHANT MELAKMA ---- . ................................ 8-1
Summary [[[ •. ..... 8-1
Findings ........................... ; ............................. 8-3
Introduction ... ......... . ........ . . . ...................... ~ ...... 8-7
Epiolsjiologic Evidence .............. . ............................ 8-U
Experimental Evidence .............. ;.'... ......... .. ............... 8-28
Dose-Response Relationships .................... ,..»... ........... 8-29
References ..... .......... .. ....... . ................ . ............. 8-41
9. DVR-IHDUCED DOfDHOSDPFRESSIOR: "CHARACTERISTICS AID
IMPACTS ................................... ..
Suamary [[[ 9-1
Findings ................................. . ....................... 9-3
Introduction ............... ...................................... 9-5
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ES-68
PAGE
Human Studie* .- *. 9-14
Effects of Ultraviolet Radiation oa Infectious Diseases 9-15
References 9-18
10. CATARACTS AND OTHER EYE DXSOtB0S 10-1
, 10-1
Findings '. '. 10-2
Cataract* .: 10-3
Potential Change* in S«nil« Cataract Prevalence for
Changes in DV-B 10-29
Other Eye Disorder* 10-33
References 10-37
11. RISKS TO CROPS AND TERRESTRIAL ECOSYSTEMS FROM ENHANCED
UV-B RADIATIOH 11-1
Suanary 11-1
Findings , 11-2
Introduction 11-5
Issues and Uncertainties in Assessing the Effects
of UV-B Radiation on Plants 11-5
Issues Concerning UV Dose sad Current Action Spectra
for UV-B Impact Assessment 11-5
Issues Concerning Natural Plant Adaptations to UV Radiation 11-7
Issues Associated with the Extrapolation of Data fro*
Controlled Environments to the Field 11-10
Uncertainties in Our Current Knowledge of UV-B Effects on
Terrestrial Ecosystems and Plant Growth Forms 11-11
Uncertainties with the Ability to Extrapolate Knowledge to Higher
Aabient C02 Environment sad Other Atmospheric Pollutants 11-13
Risks to Crop Yield Resulting from an Increase in
Solar UV-B Radiation 11-15
Risks to Yield Due to a Decrease in Ojuality U-20
Risks to Yield Due to Possible Increases In
Disease or Pest Attack Jtrr; 11-20
Risks to Yield Doe to Competition with Otter Plants 11-22
Risks .to Y$»ld Due to Change* la Pollination and Flowering 11-23
References 11-25
12. AH ASSESSMENT OF THE lHHa» OF ULTRAVTOLZT-B
RADIATION OH AQUATIC ORCAIfTSHS 12-1
Summary '. 12-1
Findings 12-2
Introduction 12-4
Background on Marina Organisms and Solar Ultraviolet
Radiation - 12-*
Effects of UV-B Radiation in Fltytwlsnliftn ............«•••••••••• 12-9
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ES-69
TABLE OF UJB1U1&
PACE
Effaces on Invertebrate Zooplankton 12-11
Effects on Ichthyoplankton (Fisheries) .„.«..... 12-23
Conclusion* 12-28
References ... „ 12-29
•
13. EFFECTS OP UV-B ON POLYMERS „ '... 13-1
Su*Bary .". 13-1
findings .... 13-2
Pbotodegradation of Poly»ers 13-4
Polymers in Outdoor Uses and the Potential for Degradation 13-7
Dsaage Functions and Response to Daaage 13-16
Effect of Temperature and Humidity on Photodegradation 13-29
Future Research * 13-31
References «...,... 13-32
14. POTENTIAL EFFECTS OF STRATOSPHERIC OZONE DEPLETION OH
TROPOSPHERIC OZONE 14-1
Summary 14-1
Findings 14-2
Introduction 14-3
Potential Effects of Ultraviolet Radiation and Increased
Temperatures on Ground-based Ozone 14-5
Conclusions and Future Research Directions 14-9
References • 14-14
15. CAUSES AND EFFECTS OF SEA LEVEL RISE 15-1
Susnary 15-1
Findings 15-2
Causes .of Sea Level Rise 15-5
Effects of Sea Level Rise „ 15-15
Conclusion ,. 15-32
Hots* !.'.'.'.'.'.'.'.'.'.'/.'.'.'.'.'.'.'.'.'.!!!!!I!!!I™*!*""*! ..15-33
References 15-34
16. POTENTIAL EFFECTS OF FUTURE CLIMATE CHARGES OH FORESTS
AND VEGETATION, AGRICULTURE, HATER. RESOURCES
AHD HUMAN HEALTH ;. 16-1
ary 1$-1
Findings 16-5
References ^ 16-10
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ES-70
OF
sued)
PACE
17. MODELS FOR. IHTEG&AXXBG THE AHALTSES OF ««ATTU
. £ISKS ASSOCIATE) WITH OZOBE MODITICATIOH 17-1
17-1
Introduction ..., , .. 17-2
The Modal as a-Framework , <.!.I!II1!!!!I!! 17-2
Analysis Proeadura .. 17-4
Modal Limitations 17-9
Rafaranca* 17-11
Appendix A: Model Design and Modal Flow .. A-l
Appendix B: Scanarios of fihaairsl Production, Population,
and CMP B-l
Appandix C: Evaluation of Policy Alternatives C-l
Appendix 0: Emissions of Potential Oxone-Depleting Compound* D-l
Appandix E: Ataospharic Scianca Modula B-l
Appandix F: Haalth and EnvlronBantal Lapaets of Ccona
Daplation F-l
18. HUMAN HE1ATH AND ENVIRONMENTAL EFFECTS 18-1
Suaaary ,... 18-1
Findings 18-2
Introduction 18-6
Methods for Estimating Haalth and Exnriroaasntal Kisks 18-11
Daacription of Ranga of Production, Emissions, and Concantrations
Scanarioa for Evaluating Risks 18-12
Sansitivity of Haalth and Environaantal Effacts to Oiffarancaa
in Emissions of Ozona Daplatars 18-18
Sansitivity of Raaults to Altarnativa Atmospharlc Assumptions 18-23
Sansitivity of Effacts to Oncartainty in Doaa Rasponsa 18-54
Ralativa Importanca of Kay Uncartaintias 18-61
Summary 18-62
Rafarancas 18-65
X*
Appandix A
Ultrsviolat Radiation and
Appandix B
Potantial Effacts of Future Climata Changas on Forests and
Vegetation, Agriculture, Water Resources, and Tftaisn Haalth
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IS-71
VQUME VI
Technical Support Documents
LSC C
Projecting Production of Ozone Depleting
Technical Support Doeu»«nts
Appondix D
Scientific Pcpor»
fDUDHE 7ZZZ
Technical Support Docuaents
Appendix E
Current Risks end Uncertainties of Stratospheric Ozone Depletion
Upon Plants
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ES-72
LIST OP EXHIBITS
1-L Relationships Among the Chapters 1-3
2-1 Measured Increases in Tropospheric Concentrations
of CFC-11 (CTC-13) , 2-5
2-2 Measured Increases in Tropoapbarie Coneentrationa
of CFC-12 (CF2CL2) '. 2-6
2-3 Measured Inereaaea in Tropoapheric Coneentrationa
of HCFC-22 (CHC1F2) 2-7
2-4 Measured Inereaaea in Tropospheric Coneentrationa
of CFC-113 (C2CL3F3) 2-7
2-5 Measured Increased in Tropospheric Coneentrationa
of Carbon Tetriehloride (CC14) 2-9
2-6 Measured Increases in Tropospheric Coneentrationa
of Methyl Chloroform (CH3CC13) 2-10
2-7 Measured Increases in Tropospheric Coneentrationa
of Halon-1211 (CF2ClBr) 2-11
2-8 Measured Increases in Tropospheric Concentrations
of Nitrous Oxide (S20) 2-12
2-9 Measured Increases in Tropospheric Coneentrationa
of Nitrous Oxide (N20) 2-14
2-10 lee Core Measurements of Historical Nitrous Oxide
(N20) Concentrations 2-15
2-11 Measured Inereaaea in Tropospheric Concentrations
of Carbon Dioxide (C02) 2-16
*
2-12 lee Can Measurements of Historical Carbon Dioxide
(C02) Concentrations 2-17
2-13 Measured Increases in Tropoapbarie Concentrations
of Methane (CH4) 2-19
2-14 Ice Core Measurements of Historical Methane (CH4)
Coneentrationa 2-20
2-15a CFC-12: Constant Emissions 2-23
2-L5b CFC-12: Atmospheric Concentrations .' 2-23
2-16a CFC-12: Emissions .;.... 2-24
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ES-73
LIST OF HUHIMfct
2-16b CFC-12: Ataoapharlc Coneancratioaa i 2-24
2-17 CFC-12: Ataoapharic Concentration* from Different
Eaiaaion Trajactoriaa „ '., 2-25
A-l Concentration* of Fluoroeatbeaa ..« '..... 2-29
A-2 Location* of Station* 2-29
3-1 Salaetad Propartlaa of CFCS 3-8
3-2 CFC Charaetariatiea and Subatitutaa 3-10
3-3 Coapanie* Reporting Data to CMA 3-11
3-4 Production of CFC-11 and CFC-12 Baportad to CMA ........... 3-13
3-5 Historical Production of CFC-11 and CFC-12 3-15
3-6 CFC-11 aad CFC-12 Uaad in Aaroaol and Honaeroaol
Application* in tba EEC , 3-16
3-7 Coapariaon of Eatiaated CFC-11 DM: 1985 3-18
3-8 Coaparicon of Eatiaated CFC-12 Baa: 1985 3-19
3-9 Ectiaate* of Production and Eaiaaiona of CFC-11
and CFC-12 3-21
3-10 Published Eatiaataa of U.S.S.R. Production of CFC-11
and CFC-12 3-22
3-11 Historical Production of CFC-11 and CFC-12 in the U.S 3-24
•' .'ji.
3-12 EIC Production arkl Salaa Data 3-25
3-13 Tha Bottoa Up Approach 3-27
3-14 Rang* of Population and GBP Pax Capita Projection* 3-30
3-15 Suaaary of Oaaaad Projection Ictiaata* 3-32
3-16 Suaoary of Oaaaad ProJaction Sattaata*
(Average annual rate of growtii in parcant) .- 3-34
3-17 Long Tata Projection* CFC-11 and CFC-12 -
World Production (2000-2050) 3-35
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5-74
3-18 Bavlngton'* Projections for Use of CFC* In the DC ........ 3-38
3-19 Cemm Projections of World U*e '.. 3.40
3-20 Summary.of KFCTC Projections 3-42
3-21 Global Population and 60 Scenario* Used in
Gibbs' Analysis 3-43
3-22 Gibbs Scenarios of World CFC Use 3-45
3-23 Bammitt Projections of World CFC Use 3-47
3-24 Susmary of Bedenstrom Projections for Sweden ;... 3-49
3-25 Knolly* Projection* '. » 3-51
3-26 Summary of Kurocawa Projection* for Japan 3-53
3-27 Hordhau* Scenario* of world Honaarosol CFC Consumption .-... 3-55
3-28 Summary of Sheffield Projections for-Canada .-ic.:. 3-57
(1984-2005)
3-29 Global Balon Projections for Quinn TJ.'. 3-62
3-30 Bemmitt and Came Global Balon Projection* 3-64
A-la Global Annual Production in Millions of Kilograms A-4
A-lb U.S. Annual Production In Million* of Kilogram* A-4
A-2 Assiapffmis for He Balon PrejectJsos A-5
A-3 Me Projection* of Sale* and Emissions for Halon-1301
and Balon-1211 ......... A-6
A-4 Global Halon-1301 and Balon-1211 Growth Bates A-7
A-5 Dupont Ectimates of CFC par Capita Us* *.. A-8
4-L Effects of Change* in Composition of Atmosphere 4-5
4-2 Bi*torical Carbon Dioxide Emissions from Fossil Fuels
and Cement ... ;. 4-7
4-3 A Schematic of the. Carbon Cycle 4-8
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ES-75
LIST OF
4-4 Projected Carbon Dioxide Emissions and Doubling
Time of Concentrations 4-10
4-5 Estimated CB4 Emission Soureaa (10 grams mar year) • 4-12
4-6 Two Says 'That CB4 Concentrations Could Batvm Changed ....... 4-14
4-7 Poaaible Changes in CB4 Soureaa and la
Emission Factors * 4-15
4-8 Currant Soureaa and Sinks of Carbon Monoxida
(1984 concentration of CO: 30-200 ppb) 4-17
4-9 Scenarios of Carbon Monoxide (CO) Emissions from
Combustion 4-18
4-10 Preliminary Scenario of Future Growth in B20
Emissions by Source 4-21
4-11 Projected Nitrous Oxide (K2O) Concentrations 4-22
4-12 Summary of Standard Scenarios Proposed for Assessment ..... 4-24
5-1 Temperature Profile and Ozone Distribution in the
Atmosphere 5-7
5-2 Steady-State Scenarios Used in International Assesamant ... 5-10
5-3 Change in Total Ozone from Representative One-Dimensional
Models for Steady-State Scenarios *V*r*-1"f«*t Clx
Perturbations 5-12
5-4 Change in Total Ozone at 40 Kilometers for Steady-Stata
Scenarios Containing Clx Perturbations 5-13
5-5 Change in Total Ozone for Steady-State Scenarios 5-14
5-6 Effect of Stratospheric Nitrogen (BOy) on Chlorine-Induced
Ozone Depletion 5-15
5-7 Effect of Doubled C02 Concentrations on Ozone
Temperature ,. 5-16
5-8 Calculated Changes in Ozone Versus Altitude 5-17
5-9 Two-Dimensional Modal Scenarios Used in International
Assessment 5-19
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ES-76
LIST OF EXHIBITS
CContlnttad)
^ ^^^^^•^•^I^^^^^^^P^
Paga
5-10 2-Dinenaional Model Raaulta: Globally and Saaaonally-
Averaged Ozone Depletion „.' 5-20
5-11 Ozone Depletion by Latitude, Altitude, and Seaaon for Clx
lacraasa of 6.8 ppbv (MPIC 2-0 Model) ' 5-21
5-12 Oxone Depletion by Latitude, Altitude, and Month for Clx
Increase of 6.8 ppbv (AKR 2-0 Modal) 5-22
5-13 Ozone Depletion by Latitude, Altitude, and Month for Clx
Incraaaa of 14.2 ppbv (AKR 2-D Modal) 5-23
5-14 Ozone Depletion of Latitude, Altitude, and Month for Clx
Increase of 6.8 ppbv (GS 2-0 Modal) 5-24
5-15 Ozone Depletion by Latitude and Season for Clx Increase
of 6.0 ppbv (IS 2-D Modal) (AIR 2-0 Modal) 5-25
5-16 Change in Ozone by Latitude and Season for Clx
Perturbations (MPIC 2-0 Modal) 5-26
5-17 Change in Ozone by Latitude and Season for Clx
Perturbations (AZR 2-0 Model) 5-27
5-18 Latitudinal Dependence of AER and MPIC 2-0 Models 5-28
5-19 Change in Ozone by Latitude, Altitude, and Month for
Coupled Perturbations (GS 2-0 Model) 5-29
5-20 Changes in Ozone by Latitude, Altitude, and Season for
Coupled Perturbations (MPIC 2-D Modal) 5-30
5-21 Changes in Ozone by Latitude *r*** Altitude in Winter for
Coupled Perturbations (MPIC 2-D Modal)' „ 5-31
5-22 Models With Reported Tim* Dependent tuna 5-33
5-23 LLHL 1-D Modal Versus Parameterization Fit 5-34
5-24 Trace Gaa Assumptions for Raaults in Exhibit 5-2S
(Brassaur and DaRuddar 1-D Modal. 1986) 5-35
5-25 Tine-Dependent Change in Ozone for CFC Growth and Coupled
Perturbations (Brassaur and DaRuddar 1-D Model) 5-36
5-26 Tine-Dependent Change in Ozone for Constant CFC Emissions
and Growth in Other Trace Gaaas (Braaaaur and Oeindrtar
1-DModal) .*.... 5-37
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ES-77
LIST OF
5-27 Sensitivity of 1-D Models to Representation of Radiative
Processes (Brasseur and DeRudder 1-D Model) 5-38
5-28 Model Comparison: Time-Dependent Change in Ozone for CFC •
Growth and Coupled Perturbations 5-39
t
5-29 Trace Gas Assumptions for Results in Exhibit 5-30
(AER 1-D'Model. 1986) '. 5-41
5-30 Time-Dependent Change in Ozone for Various Scenarios of
Coupled Perturbations (AER 1-D Model) 5-42
5-31 Trace Gas Scenarios Tested in LLHL 1-D Model 5-43
5-32 Time-Dependent, Globally Averaged Change in Ozone for
Coupled Perturbations (IZJO. 1-D Model) "Reference Case9 ... 5-45
5-33 Tim* Dependent, Globally Averaged Change in Ozone for
Coupled Perturbations (UAL 1-D Model) 5-46
5-34 Effect of Potential Greenhouse Gas Controls on Ozone
Depletion (Results from 1-D Parameterization) 5-47
5-35 Calculated Ozone Depletion for 1970 to 1980 Versus
Umkahr Measurements 5-49
5-36 Tim*-Dependent Globally and Seasonally Averaged Changes
in Ozone for Coupled Perturbations (IS 2-D Model) 5-50
5-37 Time-Dependent Globally and Seasonally Averaged Changes
in Ozone for Coupled Perturbations (IS 2-D Model) 5-51
5-38 Time-Dependent Seasonally Averaged Change in Ozone for
1980 CFC Emissions and Coupled Perturbations (IS 2-D
Model) 5-52
5-39 Time-Dependent Seasonally Averaged Change in Ozone for
1.2% Growth i*> eye Emissions *r**f Coupled PrrTTfratslopT
(IS 2-D Model) 5-53
5-40 Time-Dependent Seasonally Averaged Change in Ozone for
3% Growth in CFC Emissions sad Coupled Perturbations
(IS 2-D Model) 5-54
5-41 - Tim*-Dependent Seasonally Averaged Change in Ozone for
3.8% Growth in CFC Emissions and Coupled Perturbations
(IS 2-D Model) 5-55
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ES-78
LIST Of HHXBZ7S
5-42 Temperature Feedback Experiment: Time-Dependeat, Globally
and Seasonally Averaged Change ia Ozone for 3% Growth ia
CFC Emissions aad Coupled Perturbations (IS 2-0 Model) .... 5-57
5-43a Two-Dimensional* Time-Dependent Simulation for Constant
CTC Emissions (AIR. 2-D Model) .'. 5-58
5-43b Two-Dimensional, Time-Dependent Simulation for CTC Growth
of 62 Percent Per Tear (AIR 2-0 Model) 5-59
5-44 Model Comparison for Coupled Perturbations Scenario 5-60
5-45 Calcualted Ozone — Column Change to Steady-State for Two
Standard Assumed Perturbations 5-63
5-46 Latitudinal Gradients ia Odd Mitrogen: Models TS
Measurements 5-65
5-47 Logical Flow Diagram for Monte Carlo Calculations 5-67
5-48 Histogram of Measurements for a Rate Constant 5-68
5-49 Recommended Rate Constants and Uncertainties Used in
Monte Carlo Analyses 5-70
5-50 Monte Carlo Results: Change in Ozone Versus Fluorocarbon
Flux 5-71
5-51 Monte Carlo Results: Change ia Ozone Versus Fluorocarbon
Flux 5-72
5-52 Monte Carlo Results: Ozone Depletion for Coupled
Pertubations 5-73
5-53 A Monte Carlo Distribution of Column Ozone Changes
for Changes in CTC Production 5-74
5-54 Monte Carlo Results: Changes ia Ozone- by Altitude 5-76
5-55 Monte Carlo Results: Changes ia Ozone by Colon
Altitude. Onscreen Data 5-77
5-56 Monte Carlo Analysis With the LLHL l-D Model 5-78
5-57 Monte Carlo Results: Changes ia Ozone by Altitude 5-79
5-58 Ozone Trend Estimates by Latitude 5-83
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25-79
LEST OF
^^^^mm^fcaiaimmmmw*^
5-59
5-60*
5-61
5-62
5-63
5-64
5-65
5-66
5-67
5-68
5-69
6-1
6-2
6-3
6-4
6-5
6-6
6-7
6-8
Ch*ng«* i« OZMMI tTom 197*0 to 1980: Qakahr Ma««itrMMnnt
**w4 ttnAml C« 1 mil »fi eimm .........................
SBOV Zonal Trand* Batimataa Varaua •Omkahr Station
Ozona Trand Batimataa and 95% Conf idonca Intarrala ........
Ozona Trand Bmiaaiona (t par yoar) Aa Datarminod from
Balloon Ozonaaondaa Varaua Thoaa Datarminad from Dodaon
MaaauramantB (Tlao, at al . t parvonal communication)
Monthly Maana of Total Oceo* *t B*ll«y l*y ,,.,, T »,,,-,, T ,,
Himbua 7 Antarctic Ozona Maaauramanta: 12 -Day Saquanca . . .
Rimbua 7 Antarctic Ozona Maaauramanta: Maan Total
Global (60*R-60*S) Monthly Ozona Datarminad from
Preliminary Ozona Trond Data (Haaltii varau* 2-D Modal
Raaulta) (laakaan)
Stratoapharic Parturbanta and Th*ir Bffacta
Abaorption Charactariatiea of Traca Gaaaa
Radiativ* Forcing for a Uniform Incraaaa in Traca Gaaaa . . .
Iff acta of Vortical Ozona Distribution on
fuifnrt Tomparatura
Vatar Vapor, Altituda, and Radiativa Forcing
Tamparatura Sanaitivity to Climatic Faadback Machaniama . . .
Empirical Batimataa of Climata Sonaitivity era Sanaitlva
to Batimataa of Historical Tamparatura Incraaaaa aad
Ralationahip of Radiativa Forcing, Ocaan Baat Uptaka,
and Raalizad and Unraalizad Varminc
5*85
5-86
5-88
5-90
5-91
5-93
5-96
5-97
5-98
5-100
5-102
6-9
6-10
6-11
6-13
6-14
6-16
6-17
6-20
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gg.80
LIST OP EXHIBITS
6-9 Transient Estimates of Global Warming 6-21
6-10 Expected Temperature Inereasea 6-23
6-11 Results of Transient Analysis Using a General
Circulation Model 6-24
6-12 Regions of U.S.: Change in Runoff .". 6-25
7-1 Variation in UV Radiation by Latitude aa Fercent of Levels
at the Equator on March 21 at Boon *.... 7-6
7-2 UV Radiation by Month in Washington, D.C 7-8
7-3 Ratio of Instantaneous Flux Throughout the Day to
Flux at 5:15 a.m. in Washington on June 21 (Assumes
a Clear Day) 7-9
7-4 Average DRA-Dsmage Action Spectrum 7-10
7-5 Organization of the Adult Skin 7-12
7-6 Ultraviolet Absorption Spectra of Major Epidermal
Chromophores ,-..... 7-14
7*7 Skin Types and Skin Tanning Responses 7-16
7-8 Ultraviolet Action Spectra for DHA Dimer Induction,
Lethality and Mutagenicity ..., 7-19
7-9 Effectiveness of UVR at Inducing Pyrlmidine Diaers
and Transformation 7-21
7-10 Action Spectrum for the Induction of Single-Strand Breaks
in OKA 7-24
7-11 Action Sfactrua of Mouse Edeaa (MBE48) aa Compared
to that of DMA. Damage and the Robartson-Bargar
Meter ^ 7-26
7-12 Comparison of Age-Adjusted Incidence Rates Far 100,000
Persons for Squamous Cell Carcinoma (SCC) and Basal Call
Carcinoma (BCC) Among White Males and Females in the
United States 7-29
7-13 Percentage of Tumors by Anatomic Site for
Skin Cancer Among White Males and Females in the United
States (1977-1978 SCI Survey Data) 7-31
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ZS-81
LIST OF BZHXBZTS
7-14 Distribution by Sex and Aaatoaie Sito of
Skin Tuaors: Canton of V«ud, Switzerland (1974-1978) 7-32
7-15 Annual Age Adjusted Incidence Bates for Basal •
Cell Carciaoaa (1977-1978 BCI Survey Data) aad
(1973-1976 SBBB, Data) Aaong White Males 7-35
7-16 Annual Age Adjusted Incidence Bates for Basal sad "
Squaaous Cell Cirrinoass (1977-1978 9d Survey Data) and
Melanoaa (1973-1976 SBBB Data) Aaong White Foailss 7-36
7-17 Estiaated of Belative Bisks of Basal and Squaaous Coll
Carcinoaas for 32 Coabinations of Bisk Factors 7-38
7-18 Belative Mutagenieity of QV-B as a Function of Wavelength . 7-46
A-l Correlation of Alternative Measureaents of CV-B Badiation
for Ten Locations in the Halted States 7-51
A-2 Population Weights for Ton Locations in tho United
States 7-52
A-3 Estimated Dose-Response Coeffieeints (and t-Statistics) for
Basal and Squaaous Cell Skin Cancers (TJV-B Dose-Skin
Cancer Incidence) ......................................... 7-53
A-4 Estiaatod Percentage Changes in UV-B Badiation in San
Francisco for a Two and Ton Percent Depletion in Ozone .... 7-55
A-5 Percentage Change in Incidence of Basal and Squaaous Cell
Skin Cancers for a Two Percent Doplotion in Ozone for
San Francisco 7-56
A-6 Percentage Change in Incidence of Basal and Squaaous Cell
Skin Cancers for a Ten Percent Depletion in Ozone for
San Francisco '7-57
8-1 Location of Melanocyto in the Bpiderais »... 8-8
8-2 Cooperative Transaittance of U7 Badiation 8-9
8-3 Increases in Incidence and Mortality Bates froa
Malignant Melanoaa in Different Countries 8-17
8-4 Aaatoaie Site Distribution of Cutaneous Malignant
Molanoaa 8-19
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BS-82
USX OF BHXBXIS
8-5 Anatoaic Sit* Diatrlbucion of «^*-T^HII Malignant
Malanoaa by Gaodar 8-20
«-« Kalignant Ma.lanoaa liak Factor* by Maaaur** of Skin
Plgaantation Within tfaa Caucaaian Population ." 8-26
8-7 Hultipla Bay* in vhich OVt can nay a tola in
Davalopaant g.30
8*8 Suaaary Statiatie* for tograaaiona of Skin Caacar
Iscidanca *pv4- Mortality on Lat'lfytr ....................... 8-32
8-9 Eatiaatad ftalativ* Ineraaaaa in Malaaoaa Skin Cancar
Incidanca and Mortality Aaaociatad with Chang** in
Erythaaa Do** g-33
8-10 Suaaary of Faara. Scotto, and SchaaidarBaa (1977)
tograaaion Aaalysaa of Malanoaa Incidanca Doaa-Baapon** ... 8-35
8-11 Biological Amplification Factor* for Skin Malanoaa by
Sax and Anatoaical Sit* Group*, Adjusting for A«a and
Salactad Coaatitutional and tzpoaura Variablaa 8-35
8-12 Biological Amplification Factor* for Malanoaa laeidaaca
by Sax and Anatomical Sita Croup*, Adjuating for Aga
and Coabinationa of Salactad Constitutional and
Expoaura Variablaa 8-36
8-13 Pareantag* Zncraaa* in Malanoaa Oaatib lataa for a On*
Parcant Oaclina in Oxoua 8-39
9-1 Action Spactra for Local Suppraaaioa of Contact
ByparaaaaitiTity Aa«aaia§ tlthar Ona-Mt or Multi-ait
.Vi 9-11
9-2 Action fpactrua For Syataadc Suppraaaioo of Contact
. ........... ... .......... ^ .................. 9-12
10-1 Cataract Pravmlane* by WT Zona ..... . ...................... 10-7
10-2 Coapariaoa of Cataract Fravalaae* for Aboriginaa and
Mon-Aborigina* .......... . .......... ... ..... . ............... 10-7
10-3 Coapocita Traaaaittanca Curw* for tiba Babbie ............ . 10-9
10-4 Calculated Total Tranaaittanc* of th* Huaan Eya ........... 10-10
10-5 Parcant Tr«n*ai**ivtcy Through th« Entir* Rha*us Ey* ...... 10
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ZS-83
UST OP EXHIBITS
10-6 Tranaaittanea of tha Total tabbit Goroaa. tha Total
Buaan CotnM, and tha Rabbit Cotnaal Epithaliua . 10-12
10-7 Tranaaittanca of tha Antarior-Ocular Structiuoa of
tba Btavm and Babbit Eyaa 10-13
10-8 0V Radiant Expoaura Thraahold Data for tha
Hr, Lana HL Cataracta, and Batina H_
for tha tabbit and Priaata 7 10-14
10-9 Tba Action Spoetra for Photokaratitia and Cataracta
for tha Priaata and tabbit 10-15
10-10 Fraa P«dt?fllt tr4 Oxidation: taduction tjacaai ... ......... 10-17
. »
10-11 Enryaa Syataam Involved in Oxidation: tadaetion ........... 10-18
10-12 Standardized tagraaaion Coaflieianta for Cataract ......... 10-31
10-13 Eatiaatad talationahip Batvoan tiak of Cataract
and UV-B Flux ............................................. 10-32
11-1 A Suanary of Studiaa Itr*"*"**! **»* Sansitivity of Cultivarc
to UV-B Radiation ......................................... 11-8
11-2 Survay of UV Studiaa by Major Tarraatrial Plant
Ecosyataaa (aftar Vhittakar 1975) ......................... 11-12
11-3 Suaaary of UV-B and C02 Effacta on Planta ................. 11-14
11-4 Suaaaxy of Fiald Studiaa BraainJTH tba Kffacta of
UV-B Radiation on Crop Yialda ....* ................... *.... 11-16
11-5 Dataila of Fiald Study by Taraaura, <1981-1985) ............ 11-17
11-6 Itiam i j of Changaa in Tiald Quality in Soyboan
Batvaon tha 1982 and 1985 Growing Saaaona
(Taraaura 1982-1985) 11-21
12-1 Solar Irradianca Outaida tb* larth'a AtBoapharo and at
ch« Surfaca of tb« Earth for * Solar Zanith Angla of 60*... 12-5
12-2 talationahip Batwaan Oxona Daplation and Biological
Effactivanaaa of Incraaaad UV-B Radiation 12-6
12-3 Solar Spactral Irradianca at tha Surfaea of tha Ocaan
and at Four Daptha 12-7
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ES-84
LIST OP UK! BTTS
^•a^sewABHaiaaavspvav^
Pjgt
12-4 Lethal Effects on Shrlap Larvae for Various Coabinations
of DV-R, Dose-Rate, and Total Dose 12-13
12-5 Estiaatad Effective UV-B Solar Daily Dose at Various
Atteospherlc Ozone Concentrations Baaed on a 4-Year
Mean of Medians, Manchester, Washington, 1977-1980 12-14
12-6 Estiaatad Biologically Effective UV-B Doses Leading to
• Significant Effects in Major Marina Zooplaakton Groups .... 12-17
12-7 Percentage of Total Dose Halt to be Reached on Any
Particular Day: Lethal Doses Accuaulatad Only After
Dose-Bate Threshold is Exceeded 12-20
12-8 Effect of Increased Levels of Solar OV-B Radiation on
tha Predicted Loss of Larval northern Anchovy froa Annual
Populations, Considering the Dose/Doee-Rate Threshold
and Three Vertical Miacing Models 12-27
13-1 Vcvalangths of DV Radiation and Polyaars with
Sensitivity and Corrasponding Photon Bnargias 13-4
13-2 Plastics Usad in Applications Vhara Exposura of tha
Matarial to Sunlight Might Ba Expactad 13-8
13-3 Modas of Daaaga Exparianead by Poljaara Usad in
Outdoor Application .' 3-11
13-4 PVC Siding Compound Coapoaition 13-13
13-5 UV Seraaning Effactivanass of Salactad Pigpants 13-14
13-6 DosMStie Conauajption of Light Stabiltmars, 1984-85 13-15
13-7 IncraaMd Stabilization Markat (1970-2020) 13-18
13-8 Oxooa aeplation Estiaatas 13-19
13-9 Qawlatlm Addad Cost 13-20
13-10 Diagraamatic Bapraaantation of tha Iff act of
Pigaant/Fillara as Light Shialdars
(Monodisparsa Spharical FUlar) 13-22
13-11 Ralativ* Daaaga Zndieas for Yallovlng of PVC Ttadar Miaai
(March 22nd) Conditions, at Diffarant Extanta of
Ozona Layar Datarioration 13-25
13-12 Estiaatad Rangas of Factor Incraasa in Daaaga and tha
Factor Incraasa in Stabilizer Naadad to Counter tha
Change of Yellowing of Rigid PVC Compositions 13-28
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ES-85
LIST Of OH I FITS
(I
13-13 PVC Damage with Ozone Depletion 13-29
13-14 Projections of Future Demand for Selected Y«
(Thmitsndt of Metric TOM) 13-30
14-1 Ozone Concentrations for Short-Term Exposure That
Produce 5% to 20% Injury to Vegetation Growth Under
Sensitive Conditions 14-6
14-2 Ozone Concentrations at Which Significant Yield •
Losses Have Been Noted for a Variety of Plant
Species Exposed Under Various Experimental Conditions 14-7
14-3 Ozone Concentrations Predicted for Changes in
Dobson Number and Temperature for Three Cities (ppm) 14-10
t
14-4 Global Warming Would Exacerbate Effects of Depletion
on Ground-Based Ozone in Nashville 14-11
15-1 Snow and Ice Components 15-6
15-2 Worldwide Sea Level in the Last Century 15-8
15-3 Temperature Increase At Various Depths and Latitudes 15-10
15-4 Estimates of Future Sea Level Rise 15-13
15-5 Local Sea Level Rise 15-14
15-6 Evolution of Marsh as Sea Level Riaas 15-17
15-7 Composite Transect — Charleston, S.C 15-18
15-8 Louisiana Shoreline IB the Year 2030 15-20
15-9 Distribution of Population in »—»*-«—* 15-21
15-10 Ae Bruun Rule 15-23
15-11 Percent of Tidal Cycle* in Which Specified
Concentration is Exceeded at Torrasdale During a
Recurrence of the 1960's Drought for Throe Sea Level
Scenarios 15-28
15-12 Estimates of Flood Damages for Charleston and Call
Resulting From Sea Level Rise 15-30
16-1 Summary of Findings from the OMO/OHEP/TCSU Conference
on Global Climate Held in Villach, Austria, October 1985 .. 16-1
17-1 Modular Structure 17-3
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ES-86
vat or
C
17-2 Major Modal Input Choieaa 17-5
17-3 Bffecta »ot Quantified 17-10
A-l Flow of. Aaalyaia Program A-4
A-2 Pilea Required to Specify a Run . A-6
B-l Ftttura Global Production Scaaarioa: Middla Scaaario B-3
B-2 Ragioaal Uaa Sharaa for CFC-11 .....' B-4
B-3 U.S. End Uaa Sharaa far CFC-11 B-6
B-4 Middla U.S. Population Seanario B-7
B-5 Middla U.S. GNP Scaaario B-7
B-6 Uaar-Modifiad Seaaario Specifying a Growth Rata of 2
Parcant Annually for CFC-11 la the U.S B-9
B-7 A Uaar-Modifiad Seaaario: Production aa a Function of
Population B-9
0-1 Raleaae Tablaa for C7C-11 _ D-2
0-2 Eaiaaiona from a Hypothetical 100 Million Kilogram* of
Production in 1985 0-4
0-3 Emiaaiona from Production Over a Seriaa of Tears
(Milliona of Ulograma) 0-5
0-4 Sample Tabla of Exoganoualy Specified Emiaaiona 0-6
E-l Trace Gaa Aaaumptiona Uaad to Develop the Ozone Depletion
Relationship .» ..i?t^ 1-2
E-2 Compaxtaoa of Total Column Ozoaa Daplation Baaulta from
tha 1-0 Modal and tha Paramatarixad Bumvrical Fit ......... E-3
E-3 Hypothatieal Tabla of Qaar-Spaeiflad Ocoaa Oaplatioa ...... E-6
S-4 Exampla Osona Oaplatioa Scaling Factors ................... E-7
F-l Citiaa Uaad to Evaluata Chaagaa in U7 Flux for tha .Taraa
Ragiona of tha U.S ...................... ." ................. '-3
F-2 Stataa Ineludad in tha Thraa Kagiona of tha U.S. ... ....... F-5
F-3 Parcant Changa in UV aa a Function of Changa in Ocoaa
Abundance for Thraa U.S. Ragiona ........ ..... ............. F-6.
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BS-87
LIST OP EXHIBITS
F-4 Age Distribution of the U.S. Population Over Time in the
North Region F-8
P-S Baseline Incidence for Henmelanome Skin Cancers P-10
F-6 Basal Incidence for Melanoma Skin Cancers ..,„* F-12
F-7 Mortality Rates for Melanoma Skin Cancers F-14
F-8 Standardized Regression Coefficients for Cataract F-16
F-9 Estimated Relationship Between Risk of Cataract and UV-B
P-17
P-10 Sample Table for Specifying Relative Weights for Exposure
During a Person's Lifetime F-19
F-ll Coefficients Relating Percent Change in UV to Percent
Change in Skin Cancer Incidence F-22
F-12 Coefficients Relating Percent Change in UV to Percent
Change in Melanoma Mortality F-23
F-13 Dose-Response Coefficients F-25
F-14 Damage Index and Increase in Stabilizer for Ranges of
Ozone Depletion F-29
18-1 Types of Human Health and Environmental Effects
Estimated 18-8
18-2A Real World Equivalent to the No-Growth Scenario In Risk
Assessment 18-15
18-2B Real Vorld Equivalent to the 1.2% Growth Scenario in Risk
Risk Asaessment , 18*16
m
18-3 Global Average Ozone Depletion: Central Case 18-.20
18-4 Additional Cases of Hnnsulinomt Skin Cancer by Type of
Bonmelanoma , 18-21
18-5 Additional Mortality From Hnnm>1 snnsM Skin Cancer by Type
of Nonrnel •uriiM , 18-22
18-6 Additional Cases of Melanoma Skin Cancer by Cohort 18-23
18-7 Additional Mortality From Melanoma Skin Cancer by Cohort .. 18-24
18-8 Additional Senile Cataract Cases by Cohort 18-25
-------
ES-38
18-9 EznrironMatal Effaces Eatiaatad Quantitatively for tfa* U.S. 18-26
-------
ES-89
LEST OF EXHIBITS
18-10 Environmental Effects Baaed on Case Studies and Research
in Early Stage* 18-27
18-11 Equilibrium Temperature Change for the Emissions Scenarioa
Assuming 3°C Waning for Doubled CO2 18-28
t
18-12 Global Average Ozone Depletion: Comparison to Results .
with a *-D Dimensional Atmospheric Model 18-30
18-13 Climate, and Other Effects: Sensitivity to Relationship
Between Climate Change sad C02 Emissions 18-31
18-14 Summary of Effects of Greenhouse Gases on Ozone Depletion
and Global Equilibrium Temperature 18-33
18-15 Global Awrag* Oxon* D*pl*tion: Scenario of liait*
to Futur* Global Waning • 18-34
18-16 Human Health Effect*: Scenario* of Liait* to Future
Global Waning. Additional Cumulative Caaea and Dead*
Over UfatiBe* of People Alive Today 18-36
18-17 Human Health Effect*: Scenario* of Limit* to Futur*
Global Warming. Additional emulative Cue* and Death*
Ov*r Lifetime* of People Born 1986-2029 18-37
18-18 Human Health Effect*: Scenario* of limit* to Future
Global Warming. Additional Cvoulative Caae* and Death*
Over Lifetime* of People Born 2030-2074 18-38
18-19 Material*, Climate, and Other Effect*: Scenario*
of Limit* to Future Global Warming 18-39
18-20 Global Average Ozone Depletion: Methane Scenario* 18-41
18-21 Bu«*n Health Effect*: Methane Scenario* Additional
domulative Caae* and Death* Over lifetime*
*€ People Alive Today 18-42
18-22 Human Health Effect*: Methane Scenarioa
Artdtrtonal Cumulative Ca*e* and Death* Over Lifetime*
of People Born 1986-2029 18-43
18-23 Human Health Effect*: methane Emi*«ion* Caaea
Additional Cumulative Caae* and Death* Over Lifetime*
of People Born 2030-2074 18-44
18-24 Material*, Climate and Other Effects: Methane Scenarioa .. 18-45
18-25 Global Average Ozone Depletion: Sensitivity to
-------
KS-90
Relationship B*ttr*ari Ozon* D*pl«cioa and £*l««iena 18-46
-------
ES-9J.
LIST 09P 8IHLUXS
18-26 Human Health Effects: Sanaitivity to Ralationahip
Batwaan Ozona Daplation mad Eadaaiona. Additional
Cumulative Caaaa and Daatha Ovar Lifatimaa of Paopla
Aliva Today .......................................... ..... 18-48
18-27 Human Haalth Effaeta: Sanaitivity to Ralationahip
Batvaan Ozone Daplation and Imlaalona. artrtiHonal
Cumulative Caaea and Daatha Ovar Lifatimea of People
Bon 1985-2029 .................................. ... .......... 18-49
18-28 Human Haalth Effoeta: Satuilti-rlty to lalationabip
BatwMa Oxom Doplotion and toiaainna. 4iMiti«mal
Cuaulativa Caaaa and Daatha Ovar Llfatiaaa of taopla
Bom 2030-2074 ............................................. 18-50
18-29 Human Haalth Effaeta: Maximal Daplation of 95 P«rcant.
Additional Cuaulativa Caaaa and Daatiaa Ovar Ltf atiaaa
of Paopla Aliva Today ......... .. .............. . .............. 18-51
18-30 Human Haalth Effaeta: Maximum Daplation of 95 Pareant.
Additional Cuaulativa Caaaa and Oaatha Ovar Lif atiaaa of
Paopla Born 1986-2029 ....................................... 18-52
18-31 Human Haalth Effaeta: Mariana Daplation of 95 Pareant.
Additional Cuaulativa Caaaa and Oaatha Ovar Ufatiaaa of
Paopla Born 2030-2074 ....................................... 18-53
18-32 Human Haalth Effaeta: Sanaitivit? to Doaa-Raaponaa
Ralationahip. Additional Cuaulativa Caaaa and
Daatha Ovar Ufatiaaa of Paopla Aliva Today ................. 18-55
18-33 Human Haalth Effaeta: Sanaitivity to Doaa-Raaponaa
Ralationahip Additional Cuaulativa Caaaa and
Daatha Ovar Lif atiaaa of Paopla Born 1986-2029 .............. 18-56
18-34 Human Haalth Effaeta: Sanaitivity to Doaa-Raaponaa
Btla't1yp«*tip Additional Cnmiilaf !»•
Daatha Ovar Ufatimaa of Paopla Born 2030-2074 .............. 18-57
18-35 H«ai«n Haalth Effaeta: Sanaitivity to Ralationahip Baewaan
Ozona Daplation and Action Spaetrum. Additional Cumulative
Caaaa and Daatha Ovar Ufatimaa of Paopla Aliva Today 18-58
18-36 Human Haalth Effaeta: Sanaitivity to Ralationahip Batvaan
Ozona Daplation and Action Spaetrum. Additional Cuaulativa
Caaaa and Daatha Ovar Lifatimaa of Paopla Born 1986-2029 18-59
18-37 Human Haalth Effaeta: Sanaitivity to Ralationahip Batvaan
Ozona Daplation and Aetion Spaetrum. Additional Caaaa and
Daaths Ovar Liftimas of Paopla Born 2030-2074 18-60
Protection A^cno
-------
ES-52
13SI Of BHXXXXS
18-38 Coaparaeir* Saaaitivity of Mortality Fnaa Skin Caaear to
Various Factors
M.S. fmnmrn* FrtMiac Offto* : UM • «MH«M/tMU
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