ae m sowmt 4 93e17w44e No.066 P904 025

.d

March 27, 1975

Dr. Rudol f J. En gel mann

Division of ei:medical and

EnVironmental Research (DBER)

U. 5. Energy Research and

Development Administration

Washington, D.C. 20545

Daar Rudy:

With the increasing pressures for greater domestic enerqy production,

£RDA is praposing and many utility executives an urging that this comrtry s

C041 reserves be rapidly developed to serve as the backbone a United

$tateS' energy resources for at least the next hundred years, in toe

atmospheric sciences. :hese plans have prompted formation of a resesrcn

pmgram to investigate the potential sulfur/sJlfate concentraticns which

may result. But at this crucial juncture in erergy plannica, trere seems

to have oeer no critical assessment similar to tne CI4P weigning tne

relative rrerits o' fossil fuel usage and, for cumple, acclear or solar

anergy generation in which tne inalications anc conseauerces of continJing

reliance on combustion of fossil fuels and the resulting increase ia

atmospheric carbon cíoxide concentrations have been carefully considered.

Rather, an inpl cit assumption nas 4Dparently been Tade that increasing

atmospheric caroon cioxide is of no significance; a decision made without

assessing the current indications that small chances can cwse large

effects (e.g., Gmbecker, Coroniti, and Cannen, 1974).

Carbon dioxíce is the one atmospheric constituent for which there

is a very goad evidercê that it has been increasing frcm about 290 com in

the mid 1300's to more then 325 ppm at present (see, for exanale, Callendar

1958; Revelle, 1955; SCEP, 1970; SMIC, 1971). And based on extensive

studies of tne carbon cycle, it seems quite clear that the aoproximately

125 increase in atmospneric carbon dioxide corcentrations is well with n

the emission estmatas from anthropogenic sources. In fact present

estimates of C03 emssions requim that about half of the enissions be

taken up by the oceanic and/or other caraon reservoirs in order to l'mit

the rate of increase in concentrations to the rate wnich is cbservec.

A nureer of investigators (e.g., Pachta, 1972; Dugas, 1968; SCEP,

1970; Fairnall, 1973; Crarner and Myers, 1972) have attempted to mocel the

carbon cycle treating the various carbon reservoirs (nairely, the atmosphere,

biosphere, humus, mixed ccean lajer, and deep ocean) in differing detail.

And the en*ire carbon cycle has recently been reviewed in a biology related

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symposium (WMell and Pecan, 1973). While the projections for future

atmospheric :entrations di ffer, they are unanimous in seeing a continuing increase atmospheric carbon dioxide concentrations if emissions continue at re ably projected rates. These projections for the year 2000

range from apm upwards to 415 ppm, with a likely value close to 385 ppm

(Machta, 1 That is about an 18% increase over present values, and

more than 3 over the base-line value from the 1800's.

While such concentrations are small in an absolute sense and not a

direct threat to man, the range of indirect consequences seems large.

Such impacts can be expected to involve both the climate and the biosphere.

Although a trace gas, carbon dioxide plays a vital role in the atmospheric

radiation bal ance. Studies in the last twenty years have sought to refine

numerical calculations of the potential effects and current estimates,

which attemot ta account for at least some other atmospheric mechanisms

(e.g., convective adjustment), indicate that a doubling of carbon dioxide

(from 300 pcn to 600 ppm) would increase global average surface temperature

by 2 to 3 K ( see for example Manabe and Wetherald, 1967 and a draft review

Schneider, 1975). There have been, so far, only a limited number of studies

of the climatic effect in multi-dimensional models (e.g., Manabe and

Wetherald, '975) and these tend to indicate the effect will be at least

as large as incicated by radiation models alone. What has not been done

is to interpret the effects of these changes on man in terms of agriculture,

life-style, oman level, polar melting, etc. It should be noted, however,

that the obsered climate has responded somewhat di fferently than increase.d

CO2 alone woul a predict, and may do so in the future. This may be due to

natural fl ct ations or other factors, but in any case we will someday have

to face up to tne effects of increased CO2, and should therefore be aware

of them in advance whether they be beneficial or detrimental.

The second effect is biological. Much of the biological cycle has

been treated in the AEC Symposiun Series oublication Carbon and Bioscnere

(Woodwell and Ncan, 1975). I sense that there remains a neeo for assess ent

of the CO2 effects cascade and a ccmparison of the effects cascades bet.seen

various erercy systens. Of crucial incortance in current discussions seems

to be oceanic cnemistry and its effect on marine organisms.

I write this letter to urge that carbon dioxide effects be considered

in.evaluating eqergy strategy for tne next generation. Research see-s

needed in cl i tic effects as well as those biological areas succested in

the 1972 Caracn Synoosium. Just as there is a program on tne sul fur cyc!e,

there shculd be one on the carton cycle, trying to focus toward contiruina

evaluation of potential effects which can be used in long tenn enercy planning.

Sincerely yours,

t

MCM: cl m Michael C. MacCrack en

Ceputy Divisun ær

c: J. B. hux Atmospneric and Ceopnysical

D. H. Sìo - Sciences Otvision

Physics Deadrtuent

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Page 3

Re fe rences :

Callendar, G. S., 1958, On the Amount of Carbon Dioxide in the

Atnosphere, Tellus, 10, 243-248.

Cramer, J. and A. L. Myers, 1972, Rate of Increase of Atmospheric

Carbon Dioxide, Atmos. Environ., 6_, 563-573.

Dugas, D. J., 1968, Increase of Exchangeable Carbon in the Earth's

Reservoirs frcm Combusion of Fossil Fuels, The RAND Corporation, unpublished

manuscript.

Fairhall, A. W., 1973, Accumulation of Fossil CO2 in the Atmosphere

and the Sea, , 2441, 20-23.

Grobecker, A. J., S. C. Coroniti, and R. H. Cannon, Jr., 1974, Report

of Finding The Effects of Stratospheric Pollution by Aircraft, U. S.

Fepa-i-ta-e-nt of Trönsportation.

Machta, L. , 1972, Prediction of CO2 in the Atmosphere, in Carbon and

the Biosphere, USAEC/TIC, 1973.

Manabe, S., and R. T. Wetherald, 1967, Thermal Equilibrium of the

Abnosphere witn a Given Distribution of Relative Humidity, J. Atmos. Sci.,

24, 241-259.

Manabe, S., and R. T. Wetherald, 1975, The Effects of Doubling the

C0g Concentration on the Climate of a General Circulation Model, J. Atmos.

Sci. , 32, 3-15.

Revelle, R. , 1965, Atmospheric Carbon Dioxide, Appendix Y4 of Report

of the Environ±ental Panel, President's Adviisory_C_ommittee, The White House.

SCEP, 1970, Pan's Impact on the Global Environment: Assessment and

Recomendations for Action, recort of the Study of Critical Environmental

Problems CSCE?), ine M.I.T. Press, Cambridge, Mass.

Schneider, S., 1975, On the Carbon Dioxide--Climate Confusion, submitted

to J. Atmos Sci.

SMIC, 1971, Inadvertent Climate Modification, report of the Study of

Man's Impact on the Climate (SMIC), the M.I.T. Press, Cambridge, Mass.

Woodwell, G. M. and E. V. Pecan, editors, 1973, Carbon and the Biosobere,

Proceedin as c f

USAEC/TIL

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O e

APR 8 0 M

h8Este es AS$sshed Last

Gang grewins ggggg

Tom aey set kace that the legLalation establish1ag KEA

has charged es with (1) reviewing ongoías research re.

Lattag to emetsy, and (J) enual subestaaloa to cangrese

of a plan and program to achieve solutions to the enessy

serply and associated envinnessnal problees.

Dr. MacGraetes has semaerised the carbon dioxide issue

(anclased) at my request se that I can see it as a ettsutus

La initiatang as SMA evaluattaa og CO2 research.

would you please Les een knew

(1) Whether you believe that the Rettenal prepas as 00

18 edegiate la view of the time scale of the problem

(2) desbar you eam Edentify weaknesses tebash additieaal

fandtag would help alleviate

) what mechanise fue suggest for settling ce se answer to

the above two queettoes (for instaase, should ghs sansat Ag

chsmist042mscooreleSist teeskaber be seed to address the estreney

Year reopeases any be written er by phone (301.973.074) 11 yen

preter. Mr. David Slade wall be to the taick og ghie, so you

any cell him (J01.973.3M3) abould I be est.

39delf J. RBgelsens

Deputy Manager

Bavironmenf-41 Frepans

bec: C. L Edingtan, w/eac sim of 51easdical and

c. L. osterberg, w/encli"VI'°°°°°°°A 5'esassh

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ENVIRONM T a MAN. inc. 275 Windsor Street . Hartford Connecticut

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Dr. Lovis X4Plan

NPertasat of the Geophysical St&ance L'niv rat ty og 41cago

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042 Cantar for the Bariramassa and Nas

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