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dO 

TO T. K. Kett 

FROM HENRY S HAW 

date December 18, 1980 

Attached is the "CO2 Greenhouse Effect" 
technological forecast. I have added the 
items you suggested on 12/16/80. Pat McCall 
has not had a chance to review this draft. 

He will contact you directly if he has any 
comments . 

HS/lw 

Attachment 

cc: P. P. McCall 
H. C. Hayworth 
H. N. Weinberg 



GENERAL ' 7A 

MEMORANDUM 


H. N. W EIN, v q 

DhC 3 0 1980 




Exxon Research and Engineering Company's Technological Forecast 


CO? Greenhouse Effect 

by 

H. Shaw and P. P. McCall 


Current Status 


The build-up of CO2 in the atmosphere has been monitored con- 
tinuously at the National Oceanic and Atmospheric Administration's Ob- 
servatory at Mauna Loa, Hawaii and periodically in other places since 
1957. In addition to observing a trend between 1957-1979 that showed 
atmospheric CO2 increasing from 315 to 337 ppm, Keeling and others also 
observed a seasonal variability ranging from 6 to 10 ppm between a low 
at the end of summer growing season (due to photosynthesis) and a high 
at the end of the winter (due to fossil fuel burning for heat, and bio- 
mass decay). There is little doubt that these observations indicate a 
growth of atmospheric CO2 (See Figure 1). It is also believed that the 
growth of atmospheric CO2 has been occuring since the middle of the past 
century i.e., coincident with the start of the Industrial Revolution. 
There is, however, great uncertainty on whether the atmospheric CO2 con- 
centration prior to the Industrial Revolution was 290-300 ppm or 260-270 
ppm. 


The relative contributions of biomass oxidation (mainly due to 
deforestation) and fossil fuel combustion to the observed atmospheric 
CO2 increase are not known. There are fairly good indications that the 
annual growth of atmospheric CO2 is on the order of 2.5 to 3.0 Gt/a of 
carbon and the net quantity of carbon absorbed by the ocean is similarly 
2.5 to 3 Gt/a. Thus, these two sinks (atmosphere and ocean) can account 
for the total fossil carbon burned which is on the order of 5-6 Gt/a and 
does not allow much room for a net contribution of biomass carbon. Yet, 
highly respected scientists, such as Woodwell, Bolin and others have 
postulated a net biomass contribution to atmospheric CO2 that range from 
1 to perhaps 8 Gt/a of carbon. The rate of forest clearing has been 
estimated at 0.5 to 1.5%/a of the existing area. Forests occupy about 
50 x 10 6 km 2 out of about 150 x 10 6 km 2 of continental land, and store 
about 650 Gt of carbon. One can easily see that if 1% of the worlds 
forests are cleared per year, then this could contribute 6.5 Gt of car- 
bon to the atmosphere. Even if reforestation were contributing signi- 
ficantly to balancing the CO2 from deforestation, the total carbon stored 
in new trees would be only a small fraction of the net carbon emitted. 

It should be noted, however, that the rate of forest clearing and re- 
forestation are not known accurately at this time. If deforestation is 
indeed contributing to atmospheric CO2, then another sink for carbon 
must be found and the impact of fossil fuel must be considered in the 
context of such a sink. 


- 2 - 




Figure 2, taken out of a recent DOE publication summarizes the 
fluxes and reserviors for the carbon cycle. Note that a deforestation 
flux of 0 to 2 Gt/a and a net flux to the oceans of 4 Gt/a are assumed. 
Thus, the carbon flux to the atmosphere is 6 Gt/a of fossil fuels, and 2 
Gt/a deforestation, while 4 Gt/a returned to the ocean resulting in a 
50% carbon retention rate in the atmosphere. One of the major objectives 
of the Exxon Research and Engineering Company project to measure CO 2 in 
the oceans using tankers is to clarify and quantify the role of the 
oceans as the ultimate sink for CO 2 . 

Projections of scientists active in the area indicate that the 
contribution of deforestation which may have been substantial in the 
past, will diminish in comparison to the expected rate of fossil fuel 
combustion in the future. A number of scientists have postulated that a 
doubling of the amount of carbon dioxide in the atmosphere could occur 
as early as 2035. Calculations recently completed at Exxon Research 
indicate that using the energy projections from the CONAES study and the 
World Energy Conference, a doubling of atmospheric CO 2 can occur at 
about 2060. If synthetic fuels are not developed, and fossil fuel needs 
are met by petroleum, then the atmospheric CO 2 doubling time would be 
delayed by about 5 years to 2065. It is now clear to most people work- 
ing in the area that the doubling time will be much later in the future 
that previously postulated because of the decreasing rate of fossil fuel 
use. 

Description of potential impact on weather, climate, and land availability 

The most widely accepted calculations carried on thusfar on 
the potential impact of a doubling of carbon dioxide on climate indicate 
that an increase in the global average temperature of 3±1.5°C is most 
likely. Such changes in temperature are expected to occur with uneven 
geographic distribution, with greater warming occuring at the higher 
latitudes i.e., the polar regions. This is due to the presumed change 
in the reflectivity of the Earth due to melting of the ice and snow 
cover (See Figure 3). There have been other calculations on a more 
limited scale by a number of climatologists which project average temper- 
ature increases on the order of 0.25°C for a doubling of CO 2 . These 
calculations are not held in high regard by the scientific community. 
Figure 4 summarizes the results presented in the literature on the pos- 
sible temperature increase due to various changes in atmospheric CO 2 
concentration. 

The area of climate modeling was recently studied by a com- 
mittee of the National Research Council, chaired by Jules G. Charney of 
MIT, and the conclusions are summarized in their booklet titled "Carbon 
Dioxide and Climate: A Scientific Assessment." This National Research 
Council study concluded that there are major uncertainties in these 
models in terms of the timing for a doubling of CO 2 and the resulting 
temperature increase. These uncertainties center around the thermal 


- 3 - 


capacity of the oceans. The oceans have been assumed to consist of a 
relatively thin, well mixed surface layer averaging about 70 meters in 
depth in most of the general circulation model, and that the transfer of 
heat into the deep ocean is essentially infinitely slow. The Charney 
panel feels, however, that the amount of heat carried by the deep ocean 
has been underestimated and the oceans will slow the temperature in- 
crease due to doubling of atmospheric C02- The Charney group estimated 
that the delay in heating resulting from the effect of the oceans could 
delay the expected temperature increase due to a doubling of CO 2 by a 
few decades. 

Along with temperature increase, other climatological factors 
that are expected to occur will include uneven global distribution of 
increased rainfall, and increased evaporation. These disturbances in 
the existing global water distribution balance will have dramatic impact 
on soil moisture, and in turn, on agriculture. The state-of-the-art in 
climate modeling allows only gross global zoning while some of the ex- 
pected results from temperature increase of the magnitude indicated are 
quite dramatic. For example, areas that 4,000 to 8,000 years ago in the 
Altithermal period (when the global average temperature was some 2°C 
higher than present) were deserts, may in due time return to deserts. 
Conversely, some areas which are deserts now were formerly agricultural 
regions. It is postulated that part of the Sahara Desert in Africa was 
quite wet 4,000 to 8,000 years ago. The American Midwest, on the other 
hand, was much drier, and it is projected that the Midwest will again 
become drier should there be a temperature increase of the magnitude 
postulated for a doubling of atmospheric CO 2 (See Figure 5). 

In addition to the effects of climate on the globe, there are 
some particularly dramatic questions that might cause serious global 
problems. For example, if the Antartic ice sheet which is anchored on 
land, should melt, then this could cause a rise in the sea level on the 
order of 5 meters. Such a rise would cause flooding in much of the U.S. 
East Coast including the state of Florida and Washington D.C. The melt- 
ing rate of polar ice is being studied by a number of glaciologists. 
Estimates range for the melting of the West Antartica ice sheet from 
hundreds of years to a thousand years. 

In a recent AAAS-D0E sponsored workshop on the environmental 
and societal consequences of a possible CO 2 induced climate change, 
other factors such as the environmental effects of a CO 2 growth rate on 
the less managed biosphere were studied. For example, the impact of a 
temperature increase and a higher atmospheric CO 2 concentration on weeds 
and pests was considered. The general concensus was that these unmanaged 
species would tend to thrive with increasing average global temperature. 
The effects of atmospheric CO 2 growth on the managed biosphere such as 
in agriculture would also tend to benefit from a CO 2 growth. It turns 
out that CO 2 can fertilize agriculture, provided the other key nutrients, 
phosphorous and nitrogen, are present in the right proportions. Agri- 


- 4 - 


cultural water needs can be met by new irrigation techniques that re- 
quire less water. In addition, with highest CO 2 and higher temperature 
conditions, the amount of water that some agricultural plants may need 
will be reduced. It is expected that bioscience contributions could 
point the way for dealing with climatological disruptions of the magni- 
tude indicated above. 

In terms of the societal and institututional responses to an 
increase in CO 2 , it was felt that society can adapt to the increase in 
CO 2 and that this problem is not as significant to mankind as a nuclear 
holocaust or world famine. Finally, in an analysis of the issues as- 
sociated with economic and geopolitical consequences, it was felt that 
society can adapt to a CO 2 increase within economic constraints that 
will be existing at the time. Some adaptive measures that were tested, 
for example, would not consume more than a few percent of the gross 
national product estimated in the middle of the next century. 

Major Programs Underway 


The DOE which is acting as a focal point for the U.S. govern- 
ment in this area is considering two reports to the scientific community 
and to the policy makers. The first one, summarizing five years of 
study is due in 1984, and the second one in 1989. The current plan is 
to spend approximately 10 years of research and assessment prior to 
recommending policy decisions in this area which impact greatly on the 
energy needs and scenarios for the U.S. and the world. The national 
program on CO 2 , environment and society is summarized in Figure 6. 

Projections on When General Concensus Can be Reached 


It is anticipated by most scientists that a general concensus 
will not be reached until such time as a significant temperature in- 
crease can be detected above the natural random temperature fluctuations 
in average global climate. The earliest that such discreet signals will 
be able to be measured is after the year 2000. However, depending on 
the actual global energy demand and supply, it is possible that some of 
the concerns about CO 2 growth due to fossil fuel combustion will be 
minimized if fossil fuel use is decreased due to high price, scarcity, 
and unavailability. Figure 7 illustrates the behavior of the mean global 
temperature from 1850 to the present contained within an envelope scaled 
to include the random temperature fluctuations. 

Future Scenarios and Their Consequences For Exxon 

A number of future energy scenarios have been studied in rela- 
tion to the CO 2 problem. These include such unlikely scenarios as stop- 
ping all fossil fuel combustion at the 1980 rate, looking at the delay 
in doubling time and maintaining the pre-1973 fuel growth rate. Other 
studies have investigated the market penetration of non-fossil fuel 


- 5 - 


technologies such as nuclear, and its impact on CC>2. It should be noted, 
however, that a new technology in a competitive scenario would need about 
50 years to penetrate and achieve roughly half of the total market. Thus, 
even if solar or nuclear were to be considered viable alternatives, these 
would not really displace fossil fuel power generation for the next 50 
years or so, and CO 2 growth would have to be estimated based on realistic 
market displacement of the fossil fuel technologies. All of these studies 
tend to give a range of deviations on the order of 50 years, indicating 
a CO 2 doubling time that might be as early as 2035 (for a fossil fuel 
growth rate of 4.3%), to a doubling time occuring by about 2080 resulting 
from scenarios which assumed fossil fuel growth rates of 1 to 2%. Synthetic 
fuels will cause minor perturbations on the projected atmospheric CO 2 
growth rates in the next century. 


FIGURE 1 


Trend in Atmospheric CO 2 Concentrations 
at Mauna Loa (Hawaii) 



340 


335 


330 


325 


320 


315 


310 


1 

cr> 


Year 



FIGURE 2 


Exchangeable Carbon Reservoirs and Fluxes 


Atmosphere 



Surface 


Intermediate, 
Deep Ocean 
and Sediments 


Fossil Fuels Terrestrial Oceans 

and Shale Biosphere 


( ) = Size of Carbon Reservoirs in Billions of Metric Tons of Carbon 

Fluxes (arrows) = Exchange of Carbon Between Reservoirs in Billions of 

Metric Tons of Carbon per Year 




FIGURE 


Temperature Change 
Doubling CO? Cone 


2 x C 





I 


) 


_3 

(°C) Due to 
:entrations 


0 2 — Standard 



Decrease in Temperature 



Surface temperature change - 






Latitude 


FIGURE 5 


The Altithermal Period 



Longitude 


Wetter 



Drier 


Unknown 


FIGURE 6 


A National Program on Carbon Dioxide, 
Environment and Society 


RESEARCH 

CATEQQnV 


RESEARCH 

SUBCATEOOfiY 


ntSEAncn program 
RESULTS 


PRIMARY RCSEARCH 

products 


ASSESSMENT 


tut global 

CARBON CYCLE 


£ 


A. PlUxH Of fcOj 
V. ATMOSPULMC STORAGE 

c. past records op co 2 
o. uoonS or tiic carbon 
CYCLE 


irricTior 

INCREASING COi 
ON CLIMATE 


t— i a. modeling The irrtCTi 
I or co 2 increase 


s 


“E 


i. reconstruction op 

PAST ClIUATIS 
e. CLIMATE SCENARIO 
DEVELOPMENT 
0. CViatNCL Of CLIMATE 
CHANGE 


trrtcTsdr climate 

CHANGE AND COi 
INCREASE ON THE 
REMAlNOEnOf THE * 
ENVIRONMENT 


» a, tt f Ecti r£ tllf dcfAM 

• i. cErfccts on iiu cnvo- 

SPIltRt 

• c. ff rrcTt oit fut 

UNUANACCO lloMCRE 

• o. trncTS on IHc 

MANAGED BIOSPHERE 


ErrUnoF 

ENVIRONMENTAL 
CHANGE ON THE. 
GLOBAL SOCIETAL 
SYSTEM 


AMELIORATION 

AND/OR 

ADAPTATION 


E 


A.EPftCTOr INVtllOE. 
MENTAL fcilANOl ok 

HuklAxi SOCIETIES 

-I. effect or envircN.' 
mental change oil 
THE GLOBAL ECONOMIC 
SYSTEM 


1. REMOVAL OP 

CONTROVERSY OVtR 

lilt non op the no* 

IPHtni ASACAflBON 
SOURCE OR SINK 
1. DEVELOPMENT OP 
ACCEPTABLE FOSSIL 
FUEL USE SCENARIOS 

t. COUPLING OP 
ATAtOSPlir flic bCMWIfll 
OCTANIC VOOtl 

I. inclusion or tnvo. 

SPHERIC. ClOUOANO 
01 HER rtfOBACKS 
i. DEVELOPMENT OP 
REGIONAL DETAIL 
4. AOUISiON OP VALIDATION 
DATA FROM PALE 0* 
CLIMATIC AND GEOlOCTC 
RECORO 


. ocneric ibtNTineArioN 
op pnrJciPAL 
UNSISlVintSOf Till . 

I NVIRON MENTAL SYSTEM 
TOtOMII.IAUONS OF 
CHANCES IN CLIMATE 
COMPONENTS AN 0 
INCREASING CARBON 
DIOXIDE 


. dtfclkic loCWtiriCAtiok 
or Major MfcckANijMs 
it which populations 

RESPOND TO SLOWLY 
CHAiiQINO BUT PROPOUND 
ENVIRONMENTAL 
DISLOCATION 



- A. PAtVEfcUf IVl Ml asUrti^I 

- i. CURATIVE MEASURES 1 i 

»J C. MODERATING MEASURE! I 

b. adaptive measures \ 


GENERIC iDENTIPlCAtlON 
Of STRATEGIES FOR 
INCREASlhQ AOAPTASilltY 
OR TECHNOLOGIES FOR 
REDUCING THE BUILDUP 
OP ATMOSPHERIC CO) 


1. VAllDAttO CARBON 
CYCLE MODEL 

2. ESTIMATES OF RATES 
OF CHANGE OF 
ATMOSPHERIC CO) 


t. PARIIALLY VALIDATED 
OClAN-ATMSOPHCftC' 
itnncsrniAL' 

CHYOSPIURE OLOIAL 
MODEL 


I. oJantitative uboEiif 
or environmental 

* SYSTEM RESPONSES 


REVIEW, INTEGRATION 
AMO (VALUATION Of 
CARBON CYCLE 
INFORMATION 


REVIEW. INTEGRATION I 
ANO EVALUATION OF 
CLIMATE INFORMATION I 


DEVELOPMENT OF BEST 
ESTIMATES OF NEW CLIMATE 
STATES AS A FUNCTION OF 

co 2 ,x.y.z.t. 


1 , 

REVIEW, INTEGRATION ANO 
EVALUATION OF 

i 

ENVIRONMENTAL IMPACTS 

INF OHMATION ANO MOOILS 



IDENTIFICATION OF GLOBAL 
REOIQNS PRIMARILY 
IMPACTED ANO IDENTIFICA- 
TION OF COSTS ANO/OR 
BENEFITS 


. eoNCEPTiIULioorls 
SOCIETAL RESPONSE 


"h~[ 


REVIEW. INTEGRATION 
ARO EVALUATION Of 
SOCIETAL IMP AC IS 
INFORMATION ANO MODELS 


t. POLICY fix STRAikbV 
OPTIONS 




REVIEW. INTEGRATION ANO 
EVALUATION OF POLICY OR 
STRATEGY OPTIONS 


TO THE POLICY COMMUNITY 

icxccuTivc. copicncss. 

PUBLIC) 


tHE 1114 INTERIM ASSESSMENT REPORT 
1. DEVELOP BEST ESTIMATES OF NATIONAL ANO INTER- 
NATIONAL AGRICULTURAL. ENVIRONMENTAL ANO 
SOCIETAL CONSEQUENCES OF THE CO; ISSUE 
t. DEVELOP BEST ESTIMATES OF COSTS OF STRATEGY OR 
TECHNOLOGY ALTERNATIVES (UR AME LIUHATINQ 
UNOERSIRAILE IMPACTS 

S. COMMENT OF THE APPROPRIATNESS OF THE DlQBAl 
C0 2 RELATED RESEARCH PROGRAM TO THE MAJOR 
RESEARCH UNCERTAINTIES REMAINING 


Change of global mean temperature — 


► * 


- 12 - 

FIGURE 7 


Range of Global Mean Temperature From 1850 to the Present with 
the Projected Instantaneous Climatic Response to Increasing CO 2 
Concentrations . 



1850 


1900 


1950 


2000 


2050 


2100 




* I