ENERAL -

?84-?43

CORRESPONDENCE

DATE August 18, 198;

 

TO

REFERENCE

 

W. Glass

SUBJECT

 

FROM

R. W. Cohen

 

 

 

?effect.

I have looked over the draft of the RED reply to the
request from O'Loughlin. The only real problem I have is with
the second clause of the last sentence in the first paragraph:
"but changes of a magnitude well short of 

I think that this statement may be too reassuring. Whereas
I can agree with the statement that our best guess is that
observable effects in the year 2030 are likely to be "well
short of catastrophic", it is possible that the
CPD scenario will later produce effects which will indeed be
catastrophic (at least for a substantial fraction of the
earth's population); This is because the global ecosystem
in 2030 might still be in a transient, headed for much more
significant effects after time lags perhaps of the order of
decades. If this indeed turns out to be case, it is very
likely that we will unambiguously recognize the threat by
the year 2000 because of advances in climate modeling and
the beginning of real experimental confirmation of the C0
The effects of such a recognition on subsequent
fossil fuel combustion are unpredictable, but one can say
that predictions based only on our knowledge of availability
and economics become hazardous.

I would feel more comfortable if the first para-
graph concluded with a statement to the effect that future
developments in global data gathering and analysis, along
with advances in climate modeling, may provide strong
evidence for a delayed C02 effect of a truly substantial
magnitude, a possibility which increases the uncertainty
surrounding the post-2000 CPD scenario.

ROGER W. COHEN
RWC:tmw
Attachment

cc: H. N. Weinberg

A. J. Callegari

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*TER.OFTICE CORRESPONDENCE

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REFERENCE

See Below

SUBJECT

W. Glass

J. F. Black
R. W. Cohen
S. A. Diamond
H. Shaw
Mcrey O'Loughlin has asked Ed David for EREETS
views on the realism of CPDrs projections for fossil fuel'
2030 (attached) in view of potential
combustion out to,,acid
,,greenhouse,' and
rain" problems. I have been asked
rePlY.
short
to draft a

A prelirninary draft for EED's reply is attachedIt is based not on any calculations but on my "understanding" of what I think I've heard you say and write in
the pasl. I would appreciate your reviewing this pre-

liminary draft very critically and letting rne know ProqPtly
of any changes you would like to see. EED vrants to get an
answer back to }IEJO'L by August 2l..Thank you for Your cooPeration.
WG:

bl

Attachments

c:

T. K. Kett

 /'
. -. .?.'-a

DRAFT

EED TO !{EJO I L

you asked about our viehrs on possible emission con-

fuel consumPtion levels
out to 2030. t"luch is still unknown about the sources and
sinks for atmospheric CO2, as weLl irs about the clinatic
effect of increasing co2 levels in the air, so that Prop
gnostications remain highly sPeculative. The models that
appear most credible (to us) do predict measurable changes
in temperature, rainfall Patternr 6Dd sea-level by the year
2030 for the postulated fossil. fuel combustion rates' but
sequences of the CPD-projected fossil

changes of a magnitude well short of catastrophic and pro-

bably below the magnitude that need trigger otherwise noneconomic resPonses to the problem of energy supply.

fossil fuel contribution to the localized
problem of acid rain aPPears handlable by liniting the reJease'of SO;r NOyr and chlorides to the atmosPhere--tfhich
would decrease but by no means eliminate the economic advantage of fossil fueIs.
The

We

would be happy to discuss ttiis with you in

greater detail.

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