Cess Potter

8/8/2019 Cess Potter

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A C O M M E N T A R Y O N T H E R E C EN T C 02 -C L I M A T E C O N T R O V E R S Y

R O B E R T D . C E SSLaboratory for Planetary Atmo sphe res Research, S ta te University o f New York, S ton y Brook, N Y11794, U.S.A.an dG E R A L D L . P O T T E RLaw renc e Live rm ore Na tional Laboratory, University of Cali fornia, Livermore, C A 94550, U.S.A.

Abstract. Suggestions have persisted over the past few years that, conta ry to con-ventional estimates, increasing levels of atmospheric carbon dioxide w ill produ cenegligible warm ing o f the e arth's surface, or might even result in surface cooling.In the present paper w e reexamine several aspects o f these suggestions and illus-trate that they are either fo und ed in various violations of the first law of thermo-dynamics, or that they are based upo n misinterpretations of historical data.

1. Introduction

T h e p a s t t w o d e c a de s h a v e p r o d u c e d n u m e r o u s m o d e l s tu d ie s o f t h e i m p a c t o f a n t h r o p o -g e n i c i n c r e a s e s " i n a t m o s p h e r i c C O 2 u p o n t h e e a r t h ' s c l i m a t e * . F o r t h e m o s t p a r t t h e s es t u d i e s h a v e f o c u s e d u p o n t h e c l i m a t e s y s t e m ' s e q u i l i b r iu m r e s p o n s e t o e i th e r a d o u b l i n go r q u a d r u p l i n g o f a t m o s p h e r i c C O 2 , W h i l e i n c r ea s i n g a t m o s p h e r i c C O 2 i s o f c o u r s e a t im e -d e p e n d e n t p r o c e s s, t h e s e e q u i l i b ri u m c a l c u l a t io n s a r e n e v e r t h el e s s u se f u l i n t h a t t h e ya l lo w m o d e l i n t e r c o m p a r i s o n s . F o r t h e m o s t p a rt , s u c h i n t e r c o m p a r i s o n s s h o w a g r e em e n ti n e s t i m a t e s o f C O 2 - i n d u c e d s u r fa c e w a r m i n g t o w i t h i n f a c t o r s o f a b o u t 2 t o 3 . B u t s i n ce1 9 7 9 a r g u m e n t s h a v e p er s is t e d t h a t t h e s u r f a c e w a r m i n g m i g h t b e o v e r e s t i m a t e d b y o n eo r m o r e o r d e r s o f m a g n i t u d e , a n d t h a t p e r h a p s e v e n t h e s ig n o f t h e c l i m a t e r e s p o n s e is i n-c o r r e c t. A l t h o u g h t h e r e a r e n u m e r o u s f a c t o r s w h i c h a re p o o r l y u n d e r s t o o d c o n c e r n i n gt h e c l i m a t e s y s t e m , t h e s e a r g u m e n t s p u t f o r t h n o n e w p h y s i c a l p r i n c i p l e s . I n d e e d , t h ef a il in g s o f s o m e o f t h e s e a r g u m e n t s a r e d o c u m e n t e d i n s ev e ra l e x c e l l e n t p a p e r s . N o n t h e -l es s, t h e ' C O 2 - c l i m a t e c o n t r o v e r s y ' s e e m s t o p e r si s t ( e. g ., G r i b b i n , 1 9 8 2 ) , a n d i n v i e w o ft h i s w e f e lt i t w o u l d b e u s e f u l t o s u m m a r i z e a n d r e e x a m i n e s e v er a l a s p e c t s o f th e c o n t r o -v e r s y .

B y w a y o f i n t r o d u c t i o n , a s e l ec t ed s u m m a r y o f m o d e l e s ti m a t e s o f th e e a r t h 's e q u il ib -r i u m r e s p o n s e t o a d o u b l i n g o f a t m o s p h e r i c c a r b o n d i o x i d e i s g i ve n i n T a b l e I . T h e v a lu e sl i st e d f o r ' m a j o r i t y o f e s t i m a t e s ' s t e m p r i m a r i l y f r o m t h e us e o f r a d i a ti v e - c o n v e c ti v em o d e l s a n d g e n e r a l c i r c u l a t i o n m o d e l s . T h e e s t i m a t e s b y M 6 11 er ( 1 9 6 3 ) , a n d N e w e l l a n dD o p p l i c k ( 1 9 7 9 ) , w e r e o b t a i n e d u s i n g s u r f a c e e n e r g y b a l a n c e c o n s i d e r a t i o n s , w h i le t h a td u e t e I d s o ( 1 9 8 0 ) w a s a r r iv e d at t h r o u g h u s e o f e m p i r i c a l ly d e d u c e d s u r f a c e r es p o n s ef u n c t i o n s .* Historically Tyndall (1861) was the first to describe the CO2-climate problem, while the first CO2-climate m odel was published by Arrlienius (1896).Climatic Change 6 (1984) 365 -37 6 .0 16 5 -0009 /8410 064- 0365 $01.80 .9 1984 by D. Reid el Publ ish ing Company


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36 6 Rob ert D. C ess and G erald L. PotterTABLE I: A selected summ ary of the earth's equilibrium response todoubling atmospheric CO2.Reference Glob al warming (o C)MSller (1963) 9.6M ajority of estimates (1967-19 83) 1.3 - 4.0New ell and Do pplick (1979, tropical oceans) 0.03Idso (1980) 0.26

Al thoug h M 6Ue r's e x t im a te o f 9 .6 ~ g loba l wa r m ing is we l l a bove the m a jo r i ty o fva lue s, he wa s a wa r e o f the de f ic ie nc ie s o f h i s mode l ing , wh ic h c ons i s t e d o f e m p loy ing a na tmo s phe r ic r a d ia t ion m ode l in c o n jun c t ion wi th a s u r fa c e r a d ia t ion ba la nc e . Thus , w he nc ha ng ing the a tmos p he r ic CO2 c on c e n t r a t io n , M 611er d id n o t a c c o un t f o r c ha nge s in thec o n v e c t iv e in t e r a c t i o n b e t w e e n s u rf a ce a n d t r o p o s p h e r e . B u t h e s t a te d t h a t h i s e s t im a t e dg loba l wa r ming wo u ld be l es s 'whe n the c om ple te he a t bud ge t is c ons ide r e d ' . Th e p i tf a ll so f de a l ing w i th a s u r f a c e e ne r gy ba la nc e we r e e mpha s iz e d by M a na be a nd W e the r a ld( 1967 ) , wh o a r rive d a t 2 .4 ~ g loba l wa r ming f o r CO2 doub l ing u s ing a r a d ia t ive - c onvec -t ive mo de l .

The CO2- c l ima te c o n t r ove r s y a r os e in 1979 , whe n Ne we l l a nd Dop p l ic k ( 1979 ) , e m-p loy ing a s u r f a c e e ne r gy ba la nc e wh ic h wa s r e s t r i c te d to t r op ic a l oc e a ns , f ound a ne a r -neg ligible c l ima te r e spons e to a CO2 doub l ing . Th i s wa s f u r the r f ue le d b y I d s o ( 198 0 ) , w hoa ls o f o und a s ma ll CO2- c l ima te r e s pons e ba s e d upon th r e e e mp i r i c a lly - de duc e d s u r fa c er e s pons e f unc t ions . I d s o e mpha s iz e d the a g r e e m e n t be tw e e n h is a nd Ne we U a nd Do pp l ic k ' sconc lus io ns , an d h e has re i te ra ted h is be l ie f in a small CO 2-c l imate response in severa ls ubs e que n t pub l ic a t ions ( I d s o , 1982a , b , c , d , e ) .

A l thoug h the ina pp l ic a b il i ty o f the s e a pp r oa c he s ( i. e . , Ne we l l and D opp l ic k , a nd I d s o )ha s be e n e mph a s iz e d by o th e r s (W a t t s , 1980 ; Ra m a na tha n , 1981 ; Cr a ne , 1981 , Ha ns e n e ta l . , 1981 ; W a t t s , 1 982 ) , we f e l t i t u s e f u l to s umm a r iz e the f a c t tha t , w i th in the c u r r e n ts ta te -of - the-a r t o f c l im ate mo del ing , i t i s poss ib le to reconc i le the resu l ts o f Newel l andDop p l ic k , a nd c e r ta in o f the r e s u lt s o f Id s o . Fo r the s a ke o f c omp le te ne s s we a l so inc ludeM 611er's r e s u l t in th i s e nde a vo r , a l though we c e r ta in ly do n o t r e ga r d h i s wor k a s c u r r e n t lyc on t r ove r s ia l .2 . Su r f a c e Ene r gy Ba la nc eI n th i s s e c t ion w e r e v ie w how M 611er ( 1963 ) , Ne we l l a nd Dopp l ic k ( 1979 ) , a nd on e o fI d s o 's ( 1982a , b ) a pp r oa c he s ha ve t r e a te d the s u r fa c e e ne r gy ba la nc e . Th i s ba la nc e m a ybe expressed , on a g loba l annua l average , as

F + L H + S H = Q , (1 )whe r e F a nd Q de no te the ne t up wa r d in f r a r e d a nd n e t do wnw a r d s o la r r a d ia t ion f luxe sa t the su r face , r espec t ive ly , whi le L H an d S H a r e , r e s pe c t ive ly , the upwa r d l a te n t a nds e nsib le he a t f luxe s f r om the s u r f ac e .


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A C o m m e n t a r y o n t h e R e c e n t C 0 2 - C l i m a t e C o n tr o v er s y 3 6 7Cons ide r now tha t the s u r f a ce e ne r gy ba la nc e i s pe r tu r b e d by the e ne r gy f lux G . I t

r e a d i ly f o l lows tha t the e ns u ing g lobal c l ima te r e s pons e , de f ine d he r e in te r ms o f s u r f ac et e m p e r a t u r e T s , is

T s = X x G , (2 )whe r e X is the s u r f a c e r e s pons e f unc t ion g iven by

1 d F d ( L H ) d ( S H ) d O- + - - + ( 3 )X d T s d T s d T s d T s

N o t e t h a t w e e m p l o y s u r fa c e t e m p e r a t u r e , r a t h e r t h a n t h e m o r e c o m m o n l y u s e d s u rf a cea i r t e m pe r a tu r e . The r e a s on f o r th i s i s to a ss ur e c ons i s t e nc y wi th Ne we l l a nd Dop p l ic k( 1979 ) , who d id no t a l low s u r f a c e a i r t e mpe r a tu r e to c ha nge in the i r mode l ( Ra ma na tha n ,1 9 8 1 ) .

Equ a t ions ( 2 ) a nd ( 3 ) a re s imp ly a s t a te me n t o f the f i r st l a w o f the r m odyn a m ic s . I fb o t h t h e f o r c i n g ( G ) a n d r e sp o n s e ( & T s ) a re k n o w n , t h e n X m a y b e e v a lu a t ed f r o m e i th e r .B u t c a re m u s t b e e x e r c i se d n o t t o c o m b i n e e le m e n t s o f b o t h , a n d t h e e v al u a ti o n o f Gc o r r e s ponds to ho ld ing a ll o the r p r oc e ss e s f ixe d , wh i le the e v a lua t ion o f X , f r om Equ a t ion( 3 ) , r e f e r s to the e qu i l ib r ium r e s pons e o f the c l ima te s y s te m a f t e r the f o r c ing ha s be e ninvoke d . Fo r a n inc re a s e o f a tmos phe r ic CO2 , G thus de no te s the inc re a s e in dow nw a r ds u r f a c e ra d ia t ion a s c a lc u la te d f r om a n a tmos ph e r ic r a d ia t ion mode l , bu t w i tho u t a l lowingthe s u r f a c e o r a tmo s phe r e to r e s pond to the CO2 inc r e a s e.Al though the p r e s e n t de f in i t ion o f X wa s c hos e n to be c o ns i s t e n t w i th N e we l l a ndDop p l ic k ( 197 9 ) a n d I d s o ( 1980 ) , th is de f in i t ion s u f f e rs the de f ic ie nc y o f be ing p r oc e s sde pe nd e n t ; i . e . , the va lue o f X wi ll de pe nd upo n the s pe c i fi c type o f c l ima te f o rc ing , apo in t wh ic h wi ll be i l lu st r a ted in Se c t ion 3 . M or e logic al de f in i t ions o f c l ima te r e s pons ef unc t ion s a re g ive n by La l a nd R a m a na tha n ( 1984 ) .

I n M 611e r's ( 196 3 ) CO s - c l ima te mo de l , c ha nge s in L H a nd SH we r e igno r e d , s uc h tha t1 d F d O

- ( 4 )X(M611er) d T s d T sAlthou gh Ne we l l and Dop p l ic h ( 1979 ) d id inc o r p o r a te c ha nges in L H and S H w i t h i n t h e i rs u r f a c e e ne r gy ba la nc e , the qua n t i t i e s d ( L H ) / d T s a nd d ( S H ) / d T s we r e e va lua te d by a s -s u m i n g c o n s t a n t a t m o s p h e r i c t e m p e r a t u r e a n d w a t e r v a p o r c o n t e n t d u r in g t h e r e s p o n se o fthe c l ima te s y s te m, d e s p i t e the f a c t tha t bo th he a t a nd wa te r va po r we r e a dde d to thea tm os ph e r e ( Ra m a na tha n , 1981 ;W a t t s , 1980 , 1982 ) . As f u r the r d is cuss ed by R a m a na tha n( 198 l ) , th is c o r r e s ponds to r e p lac ing the to ta l de r iva t ive s o f L H an d S H w i t h i n E q u a t i o n( 3 ) by pa r t i a ! de r iva t ive s , w i th the pa r t ia l de r iva t ive s de no t in g tha t a tmo s phe r ic pa r a me te r sha ve be e n he ld c ons ta n t . Ne we l l a nd Dopp l ic k f u r the r igno r e d a ny c l ima t ic a l ly - induc e dc ha nge in Q , s o tha t

1 d F a ( L H ) a ( S H )- + + - - ( s )X ( N & D ) d T s O T a T s


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36 8 Robert D. Cess and Gerald L. PotterThe re a r e a l so i ncons i s t anc i e s a s soc i a t ed wi th t he eva lua t ion o f d F / d T s b y N e w e l l a n dDo pp l i ck (W at t s , 1982) , b u t t h is i s a s econd-o rde r e f f ec t .

A t l a s t coun t , I d so (19 82a , b ) has dev i sed fou r me tho ds fo r eva lua t ing X , bu t t h r ee o fthese a r e emp i r i ca l eva lua t ions employ ing none qu i l i b r ium obse rva t ions and a s such a r e i n -app ropr i a t e fo r t he de t e rm ina t ion o f an equ i li b r ium re sponse . Id so ' s (1982 a , b ) so l e equ i -l i b r i u m e v a l u a t i o n p e r t a i n s t o c o m p a r i n g t h e p r e s e n t g l o b a l s u r f a c e t e m p e r a t u r e t o t h a tf o r a n e a r t h w i t h o u t a n a t m o s p h e r e , a s s u m i n g th e p l a n e t a r y a l b e d o t o b e t h e s am e i ne i the r ca se. I d so then ca l cu l a t ed t ha t i n go ing f rom an ' a tm osp he re - f r ee ' ea r th t o t hep r e s e n t e a r t h , t h e s u r fa c e t e m p e r a t u r e in c r e as e d b y 3 3 . 6 ~ a n d t h e d o w n w a r d I R s u rf a c ef lux inc reased f rom ze ro t o 348 W m -2 . Bo th num ber s a r e r easonab le . I d so then a s sum edt h a t t h e 3 4 8 W m - 2 i n cr e as e i n d o w n w a r d I R c o n s t i t u t e d t h e f o r c i n g G , s o t h a t f r o mEqu a t ion (2 ) X = 33 .6 /348 = 0 .097 ~ m -2 W -z , and th a t i s no t r ea sonab le .A s p o i n t e d o u t b y R a m a n a t h a n ( 1 9 8 2 ) , w h a t I d s o h a s a ct u a l ly d o n e i s t o p r o c e e d f r o mo n e e q u i li b r iu m s t a te ( a 2 5 4 .4 K e a r t h w i t h n o a t m o s p h e r e ) t o a s e c o n d e q u i li b r iu m s t a te( t h e p r e s e n t e a r t h - a t m o s p h e r e s y s t e m ) , s u c h t h a t h is 3 4 8 W m - 2 i n cr e as e in d o w n w a r d I Rsurface f lux i s the sum of t he fo rc ing and the r e sponse . Aga in r eca ll t ha t t he fo rc ing m us tbe eva lua t ed b y ho ld ing the o r ig inal su r f ace -a tm osph e re p roces ses f i xed , and the re is con -cep tu a l d i f f i cu l ty i n t ry ing to f i gu re ou t h ow to do th is w hen the i n i ti a l s t a t e i s an ea r thw i t h o u t a n a t m o s p h e r e . M o r e o v e r , a s a l s o p o i n t e d o u t b y R a m a n a t h a n ( 1 9 8 2 ) , I d s o h a signored a r edu c t ion o f 70 W m -2 i n t he ne t so l a r f l ux a t the su r f ace due to the add i t i ono f t h e a t m o s p h e r e . I r re s p e c ti v e o f h o w o n e m i g h t a t t e m p t t o i s o l at e f o r ci n g f r o m r e -sponse , i t f o l l ows tha t by Idso ' s de f in i t i on

1 G ( I R ) + A F ~X(Idso) ATs

or

1 G ( I R ) d ES- + - - , ( 6 )X(ldso) zx r dr s

where G ( IR ) i s u sed to no t e t ha t Id so has on ly cons ide red in f r a r ed fo rc ing , wh i l e F r de-n o t e s t h e d o w n w a r d c o m p o n e n t o f t h e s u r f ac e i n fr a r e d f l u x . T h e p o i n t h e r e , w i t h r e fe r -e n c e t o E q u a t i o n s ( 2 ) a n d ( 3 ) , is t h a t E q u a t i o n ( 6 ) c o m b i n e s f o rc i n g w i t h p a r t o f t h ere sponse .

Obv ious ly E qua t ions (4 ) , ( 5 ) , and (6 ) cons i tu t e qu i t e d i f f e r en t v io la t i ons o f t he f i r stl a w o f t h e r m o d y n a m i c s . I n t h e f o l lo w i n g w e e m p l o y a c l i m a t e m o d e l t o i ll u st r at e , f o r ad o u b l i n g o f a t m o s p h e r i c C O 2 , t h e c o n s e q u e n c e s o f th e s e v i o l at io n s .

3. A Mod e ler 's 'Ex per im ent 'I n t h i s s e c t i o n w e e v a l ua t e a c l im a t e m o d e l ' s re s p o n s e t o a d o u b li n g o f C O 2 , a n d w e t h e nr e e v a lu a t e t h a t m o d e l ' s r e s p o n s e b y e m p l o y i n g e q u a t i o n ( 2 ) t o g e t h e r w i t h X c o r r e s p o n d i n gto t he su r f ace p roces ses a s cons ide red , r e spec t ive ly , by M 6Uer, NeweU and Do pp l i ck , and


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A Com men tary on the Re cen t C02-Climate Controversy 3 6 9I d s o . T h e p o i n t i s s i m p l y t o d e t e r m i n e i f t h e v a r i a b i l i ty o f r e s u lt s a s s u m m a r i z e d i n T a b l e Ican , in e f f ec t , be r e so lved by a sing le c l ima te m ode l .

T h e m o d e l u s e d f o r t h is ' e x p e r i m e n t ' i s t h e t w o - d i m e n s i o n a l n i ne - le v e l ( l a ti t u d e -h e i g h t )s t a ti s ti c a l -d y n a m i c a l m o d e l d e v e l o p e d a t t h e L a w r e n c e L i v e r m o r e N a t i o n a l L a b o r a t o r y .T h i s m o d e l , d e s c r i b e d b y M a c C r a c k e n e t a l . (1981) , u ses a s econd o rde r f i n i t e d i f fe r ences o l u t i o n o f t h e p r i m i t iv e f o r m o f t h e e q u a t i o n s d e s c r i bi n g c o n s e r v a t io n o f m a s s , e n e r g y ,w a t e r v a p o r a n d t w o c o m p o n e n t s o f m o m e n t u m . T h e m o d e l e m p l o y s a 10 ~ l a ti tu d e g ri dwi th r ea l is t i c f rac t i ona l r ep resen ta t i ons o f ocean , l and and moun ta ins . Ra d ia t i on i s ca l-cu l a t ed i n cons ide rab l e de t a i l and inc ludes t ha t due to wa te r vapo r , c louds , ozo ne , s t r a to -sphe r i c ae roso l s and ca rbon d iox ide . Fo r p re sen t pu rpo ses t he annua l - ave rage ve r s ion o ft h e m o d e l i s u t i li z e d t o g e t h e r w i t h a s w a m p o c e a n h av i n g i m p o s e d m e r i d i o n a l h e a t t r an s -p o r t .A t t h i s p o i n t i t i s i m p o r t a n t t o n o t e a d e fi c i e n c y i n t h e m o d e l w i t h r e f e r e n c e t o a s ur -f a c e e n e r g y b a l a n c e . R e c e n t l y K i e h l an d R a m a n a t h a n ( 1 9 8 2 ) h a v e p o i n t e d o u t t h a t i n t h e1 2 - 1 8 / ~ m s p e c t ra l re g i o n t h e C O 2 b a n d s a r e o v e r l a p p e d n o t o n l y b y t h e p u r e r o ta t i o n a lb a n d o f H ; O , b u t a ls o b y t h e H 2 0 c o n t i n u u m a b s o r p ti o n . T h is l a t te r e f fe c t h a d n o t b e e ni n c o r p o r a t e d i n p r i o r s t u d i e s, w h e r e a s K i e h l a n d R a m a n a t h a n F r e d t h a t i t si g n if ic a n t lyreduces t he CO2 in f r a r ed fo rc ing a t the su r f ace . Bu t t he p o in t o f t he p re sen t exe rc i se i st o e m p l o y a m o d e l w h i c h is c o n s is t e n t w i t h b o t h N e w e l l a n d D o p p l i c k , a n d Id s o , r a t h e rt h a n w i t h r e a li ty , a n d f o r t hi s r e as o n w e to o ig n o re t h e 1 2 - 1 8 / ~ m H 2 0 c o n t i n u u m o v er -l a p. A di sc u ss io n o n t h e l a c k o f t h e i m p o r t a n c e o f t h e 1 2 - 1 8 / ~ m H a O c o n t i n u u m t o C O 2 -induce d su r f ace warm ing is g iven in a l a t e r s ec t ion .

T h e r e l e v a n t m o d e l o u t p u t s , f o r a d o u b l in g o f a tm o s p h e r i c C O 2 , a re s u m m a r i z e d i nTab le I I . H ere G den o te s t he 2 x CO2 in f r a r ed fo rc ing a t t he su r f ace , eva lua t ed f ro m them o d e l ' s f ir s t r a d i a t i o n t i m e s t e p , so t h a t o t h e r s u r f a c e - a tm o s p h e r e p ro c e s se s h a v e n o tr e sponded to t h i s i n i t i a l f o r c ing . 2xTs i s t he g loba l ly -ave raged inc rease i n su r f ace t em pera -tu re due to 2 x CO 2, wh i l e t he r em a in ing quan t i t i e s r ep resen t t he r e sponse o f su r f acet r a n s p o r t p r o c e s s es . I n t h e t e r m i n o l o g y o f R a m a n a t h a n ( 1 9 8 1 ) , o u r i n i ti a l f o r c in g c o r re -spon ds t o h i s p roces s 1 , wh i l e ou r r e sponse i s t he sum o f h i s p roces ses 2 and 3 . W i th r e spec tto t he pa r t i a l de r iva tives o f L H an d S H w i t h i n T a b l e I I , r e c a l l t h a t t h e s e c o r r e p o n d t o

TAB LE II: Mo del outputs for a doubling of atmosphericCO2 relative to the model's control climate.Quantity ValueZXrsGd F d d T sd F I d r sdQIdTsd ( L ~ l d T sd(S H) d r sa (LH) IaTsa SS--O aTs

1.87 ~1.69Win -25.87 W m -2 ~ -1-0 .24 W m -2 ~ -1_0.39 W m-2 ~1.11W in -2 ~-0.3 5 W m -2 ~ -151.64 Wm -2 ~ -118.26 W m -~ ~ -1


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37 0 Robert D. Cess and Gerald L. Potterh o l d i n g a t m o s p h e r i c p a r a m e t e r s f i x e d , a n d t h e y w e r e e v a l u a te d b y i n c re a s in g t h e m o d e l ' ss u r fa c e t e m p e r a t u r e e v e r y w h e r e b y 1 ~ a n d t h e n r u n n i n g th e m o d e l t h r o u g h a s in glet i m e s t e p , s o t h a t t h e r e w a s n o r e s p o n s e o f a t m o s p h e r i c p a r a m e t e r s .

F r o m E q u a t i o n ( 3 ) 3, = 1 .1 0 ~ m 2 W - 1 w h i c h , w h e n e m p l o y e d w i th i n E q u a t i o n ( 2 ) ,y ie lds A T s = 1 .87 ~ s imp ly i l lu s t r a t ing cons i s t ency be tw een the mo de l ' s ac tua l g loba l r e -s p o n s e a n d t h a t e v a l u a te d f r o m t h e c o m p l e t e s u r fa c e r e sp o n s e f u n c t io n . W e n e x t e v a l u at eA T s em ploy ing 3 , a s de f ined by Equ a t ions (4 ) , ( 5 ) , and (6 ) , and these r e su l ts a r e sum ma r i -zed in Tab le I I I . I n t e r e s t i ng ly en ough , t he c l ima te mod e l p roduces a range o f g loba lwarm ing r e su l t s com parab le t o t he r ange g iven wi th in Tab le I . The po in t , o f cou r se , i st h a t i t e m s 2 , 3 , an d 4 w i t h in T a b l e I I I i n t r o d u c e i n d e p e n d e n t l y d i f f e r e n t v i o la t io n s o f th ef ir s t l a w o f t h e r m o d y n a m i c s .

TAB LE IlI: Results of the model 'experiment' .Surface process model Global warming (~1. All proc esses, 1.87Equation (3)2. M~511er, 11 .52Equation (5)3. New ell and Dopplick, 0.02

Equation (6)4. Idso, 0.25Equation (7)

Befo re p roceed ing , i t is o f i n t e r e s t t o r e tu rn t o t he po in t r a is ed ea r l ie r t ha t X , a s de f inedb y E q u a t i o n ( 3 ) a n d a s e m p l o y e d b y N e w e l l a nd D o p p l i c k ( 1 9 7 9 ) a n d I d s o ( 1 9 8 0 ) , isdepe nde n t u pon the t yp e o f c l ima te fo rc ing . To i l l u s t ra t e t h i s depe nden ce , we inc reasedt h e s o la r c o n s t a n t b y t w o p e r c e n t w i th i n th e L a w r e n c e L iv e r m o r e m o d e l , f r o m w h i c h w eob ta in ed X = 0 .70 ~ m 2 W - t , a s com pare d to X = 1 .10 ~ m -2 W -1 fo r t he 2 x CO2c l ima te change , a d i f f e r ence t h a t c l ea r ly i l lu s t r a te s t he depen denc e o f 3` up on the ma nne rin w h ich the c l ima te is changed . Such a de f i c i ency does no t , howe ver , ex t end to a c l ima tere sponse fu nc t ion de f ined in t e rms o f t he su r f ace - t ropo sphe re sys t em (e.g ., Po t t e r andCess, 1984).4. Seasonal Respon seIdso (1982a , b ) has fu r the r e m ploy ed the seasona l r e sponse o f t he c l ima te sys t em to e s ti -m a te a su r f ace r e sponse fun c t ion , f rom which he d educed a g loba l warm ing fo r 2 x CO2which i s cons i s t en t w i th h i s r e su l t i n Tab le I . Bu t Hansen e t a l . ( 1 9 8 1 ) h a v e p o i n t e d o u ttha t i n s t ead o f r e fu t ing ex i s t i ng c l ima te m ode l s , I d so ' s r e su lt s ac tua l ly conf i rm the i rm ode l ' s s easona l r e sponse , and i t is u se fu l t o am pl i fy th i s po in t .

Spec i f ica l l y , we cons ide r Id so ' s su r f ace r e sponse fun c t ion fo r t he i n t e r io r Un i t ed S t a t e s .


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A Commentary on th e Re cen t C02-Climate C ontroversy 371Em ploy ing comp i l a t i ons o f t he an nua l r ange o f i nc iden t so l a r r ad i a t i on a t t he su r f ace , Q~ ,a n d o f s u r f a c e a i r t e m p e r a t u r e , I d s o ( 1 9 8 2 b ) d e t e r m i n e d t h a t f o r t h e i n te r i o r U n i te dS ta t e s

A T s - 0 . 1 2 ~ 2 W -1 . ( 7 )zXQ*He then conv e r t ed t h i s t o a r e sponse ve r sus su r f ace fo rc ing quan t i t y , A T s / A Q , b y e m p l o y -ing a g loba l p l ane t a ry a lbedo r a the r t han the appropr i a t e s easona l su r f ace a lbedo . Becauseo f t h i s i nco r r ec t conve r s ion we wi l l , f o r p r e sen t pu rposes , cons ide r so l e ly Equa t ion (7 ) .

A s e m p h a s i z e d b y H a n s e n et a l . (1981) , t he i napp l i cab i l i t y o f Equa t ion (7 ) fo r the pu r -p o s e o f e s t i m a t i n g a n e q u i l i b r i u m ( i. e ., s t ead y s t a t e ) r e sponse i s due to t he f ac t t ha t t hes e a so n a l ' r e sp o n s e m u s t d e p e n d o n t h e r a t e o f m i x i n g o f m a r i n e a n d c o n t i n e n t a l a i r, s in c et h e p h e n o m e n a o c c u r o n t i m e s c ale s le ss t h a n t h e t h e r m a l r e l a x a t io n t i m e o f t h e o c e a nsu r f ace ' . Th i s i s ce r t a in ly a l og i ca l s t a t emen t , desp i t e Id so ' s (1982b) c l a im tha t 'mon thsmay be su f f i c i en t t o ach i eve equ i l i b r ium ove r l and a r eas ' .

To b e m ore spec i fi c on th i s po in t , i f I d so were co r r ec t i n h is con te n t ion tha t t he su r f acet empera tu re r e sponse t o s easona l so l a r fo rc ing i s , f o r midcon t inen t s , a s t eady- s t a t e r e -s p o n se , t h e n t h e n e t r a d ia t iv e i m b a l a n c e o f m i d c o n t i n e n t a l s u r f a c e - a t m o s p h e r e sy s t e m swou ld have to b e co ns t an t t h rou gho u t t he s easons . Bu t th i s i s no t t he case. Fo r examp le ,f r o m t h e s a t el li te d a ta c o m p i l a t i o n o f C a m p b e l l a nd V o n d e r H a a r ( 1 9 8 0 ) , t h e a n n u a l r a n g eo f th e n e t ( s o la r a b s o r b e d m i n u s I R e m i t t e d ) r a d i a t io n a s m e a s u r e d a t t h e t o p o f t h e a t m o -sphe re i s app rox im a te l y 180 W m-2 in t he v i c in i t y o f S t . Joseph , M issouri, a s is il l u s t ra t edin F igu re 1, and th is i s a subs t an t i a l qu an t i t y . T he ann ua l r ange o f abso rbed so l a r r ad i a t i onb y t h e s u r f a c e - a t m o s p h e r e s y s t e m at t h a t l o c a t i o n i s ro u g h l y 2 4 0 W m - 2 , w h i c h c o m p r i s e sseasona l so l a r fo rc ing , and one ce r t a in ly cann o t neg lec t 180 W m -2 r e l at i ve t o 240 W m -~ .Thus wi th r e f e r ence to Equ a t ion (7 ) , the re a r e c l ea r ly two p r im ary r e sponses t o t heseasona l so l a r fo rc ing . F i r s t , t he d i r ec t r e sponse o f su r f ace a i r t em pera tu re , and second , as e a so n a l i m p o r t ( w i n t e r ) a n d e x p o r t ( s u m m e r ) o f e n e r g y . I t is t h e l a t te r e f f e c t, h a v in gv a r i a b i li t y o v e r t h e s e a so n s o f a p p r o x i m a t e l y 1 8 0 W m - 2 , w h i c h I d s o ig n o r es , a n d o n c eaga in t h is is a v io l a t ion o f the f i rs t law o f t he rm ody nam ics .A s p r e v io u s l y m e n t i o n e d , H a n s e n et aI. ( 1 9 8 1 ) h a v e in f a c t s h o w n t h a t I d s o ' s 's e a s o n a lexpe r imen t ' i s cons i s t en t w i th t he i r gene ra l c i r cu l a t i on mode l , and to fu r the r i l l u s t r a t eth i s po in t we have eva lua t ed A T s / A Q ~ ' fo r t he midc on t in en ta l U n i t ed S t a t e s, u s ing ou t -p u t f r o m t h e G e o p h y s i c a l F l u id D y n a m i c s L a b o r a t o r y s ea s o n al g e n e ra l c i rc u l a ti o n m o d e l(M anabe and S tou f f e r , 1980) . The r e su l t i s

A T s - 0.15 ~ m 2 W -1 , (8)A Q *

in good ag re em en t wi th Ids o ' s Eq ua t ion (7 ) . M oreove r , based upon the i r 4 x CO2 s tudy( M a n a b e a n d S t o u f f e r , 1 9 8 0 ) , t h e e q u i l ib r i u m w a r m i n g o f t h e g e n e ra l c ir c u l a ti o n m o d e lw o u l d b e r o u g h l y 2 ~ f o r 2 x C O 2 , i n c o n t r a s t t o Id s o ' s n o n e q u i l i b r i u m e s ti m a t e o f0 . 2 4 ~


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37 2 Robert D. Cess and Gerald L. Potter

36O5 0 02 4 0~ J

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u .OD-o 60I- -I--- oXJ1.1_ -60

-120'd

x " " * \t \

~ J / N E T = A B S O R B E D - E M I T T E D " \ "B/ (RESPONSE) ~/ " t \/.~" \f \" / ST. JOSEPH, MISSOURI \ ~I I I 1 I I I I I [ I I ~ I n I i 1 J IF M A M d d A S 0 N

MONTHFig. 1. Seasonal variability in the compon ents of the radiation budget at the top of the atmosphere,as determined from satellite mea surem ents, for the v icinity of St. Joseph, Missouri.

5 . O b s e r v e d C l i m a t e V a r i a b i l i tyAl though Idso ' s in i ti a l con ten t ion , a s p rev ious ly d iscussed , was t ha t conv en t iona l mo de le s t i m a t e s o f C O 2 - i n d u c e d s u r f a c e w a r m i n g w e r e a n o r d e r o f m a g n i t u d e t o o l a r g e , m o r erecen t ly he ( Idso , 1982e , a , b ) has ques t ioned the s ign o f t he r e sponse . Spec i f i ca l ly , hes t a te s t h a t h e h a s ' f o u n d e v i d e n c e f o r r e la t io n s h i p s a m o n g h is t o ri c a l t e m p e r a t u r e , C O ~ ,a n d i n d u s t ri a l c a r b o n p r o d u c t i o n d a t a w h i c h i n d i c a te t h a t t h e p r i m a r y e f f e c t s o f e n h a n c edleve l s o f a tm osph e r i c CO2 m ay be t o ac tua l ly coo l t h e p l a n e t i n s te a d o f w a r m i t ' ( I d s o ,1 9 8 3 b ) .To a r rive a t t h i s sugges t ion , Id so cons ide r s 1945 to p re sen t a s a pe r iod o f r ap id i nc reasei n a t m o s p h e r i c C O 2 , a n d h e t h e n e m p l o y s h is t o ri c a l t e m p e r a t u r e r e c o r d s t o c o n c l u d e t h a ton the ave rage fo r t h i s t ime pe r iod the su r f ace a i r t empera tu re fo r Sou the rn l a t i t udes i n -c reased , fo r l ow l a t i t udes i t r ema ined cons t an t , and fo r Nor the rn l a t i t udes i t dec reased .F ro m th i s Id so (1983b ) suggest s ' t ha t t he p r im ary e f f ec t o f i nc reas ing the CO2 conc en t r a -t i on o f t he a tm osph e re o f p re sen t -day E a r th i s t o dep res s and no t r a is e su r f ace ai r t em -pe ra tu re ; fo r in No r the rn Hem isphe r i c reg ions where CO2 e f f ec t s a r e pos tu l a t ed t o beg r e a t e s t , w e s e e t h e c o m m e n c e m e n t o f d r a m a t i c c o o l i n g w h e n a t m o s p h e r i c C O 2 c o n c e n -t r a t i o n beg ins t o d ram a t i ca l l y r is e ' . One c anno t , o f cou r se , u se t h i s t yp e o f l og i c , s i nce t hee a r t h ' s c l i m a t e h a s a lw a y s b e e n h i g h l y v a ri a bl e , an d a t t r ib u t i n g N o r t h e r n H e m i s p h e r e te m -p e r a t u r e t re n d s f r o m 1 9 4 5 t o p r e s e n t a s sole ly a CO2 signal is s implist ic and naive.

Bu t r a the r t han dwe l l on th i s po in t , i t shou ld su f f i ce t o show an a l t e rna t e exemple .F igu re 2 i l lu s t r a te s a 21 -y r runn ing m ean o f a 1470 to 1974 d ryness /w e tnes s i ndex fo r B e i -


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A C o m m e n t a r y o n t h e R e c e n t C 0 2 - C l im a t e C o n t ro v e r sy 3 73

D R Y

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Fig. 2.

i i i i i i I i i i i i i

B E I J I N G , C H I N A1 I I I I I I I I I I I ]] 9 2 1 5 3 2 1 5 7 2 1 6 1 2 1 6 5 2 1 6 9 2 1 7 2 2 1 7 6 2 1 8 0 2 1 8 4 2 1 8 8 2 1 9 2 2 1 9 6 2

Y E A RTwenty-one-year unning mean of the 1470 to 1974 Beijing dryness/wetness ndex.

j ing , C h i na , a s r epor t ed by H am eed e t a l . (1983) . The r eco rd a s show n t e rmi na t e s i n 1964d u e t o t h e 2 1 - y r r u n n in g m e a n . I f w e n o w c o n s i d e r o n l y t h e 1 9 4 5 t o 1 9 6 4 p o r t i o n o f th er ecord and i nvoke Idso 's l og ic , t hen w e c ou l d conc l ud e t h a t i nc reas ing l evel s o f a tmo-spher ic CO2 have caused increased prec ipi ta t ion in Bei jing . But the fa l lacy of th i s conclu-s i on i s obv i ous w hen one no t e s t ha t t he r e a r e f i ve o t he r pe r i ods w i t h i n t he t o t a l r eco rdw here t he r e w ere subs t an t ia l i ncr eases in p r ec i p i t a t ion , and t hese ce r t a in l y canno t bea t t r i bu t ed t o an t h ro poge n i c C O 2. A mo re obv i ous conc l us ion , w i t h rega rd t o F i gure 2 andIdso ' s c l a i m , i s t ha t bo t h p r ec i p i t a t i on and t empera t u r e r eco rds fo r t he pe r i od fo l l ow i ng1945 a r e dom i na t ed b y na t u r a l va r i ab il it y .

B u t t o bo l s t e r hi s cl ai m , I dso (198 3b) r e f er s t o t he mo de l s t udy by K i eh l and R am ana-t han (1982) , w ho i nc l uded ove r l ap o f CO ~ bands i n t he 1 2 - 18 ~tm r eg ion by H 2 0 con-t i nuu m absorp t i on , s t a ti ng t ha t ' p r i o r t o t he pub l i ca t i on o f t he i r pape r , w h i ch appea red i nD ece mb er 1982 , no com put e r s t ud ie s o f t he e f f ec t s o f C O 2 on g l oba l cl ima t e had i nc l udedt hese H 20 con t i nuu m e f f ec ts ; and K i eh l and R aman a t han i nd i ca t e tha t w hen t hese e f f ec t sa r e i nc luded , t he i nc reased dow nw ard t he rma l r ad i a t i on t o t he su r f ace o f t he E a r t h a ri si ngf rom a doub l i ng o f the a t mo sphe r i c C O 2 con cen t r a t i on dec reases t o on l y abou t a t h i rd o fw h a t w as p r ev i ous l y p r ed i c t ed ' . H ow ever , a s K i eh l and R am ana t han c l e a r l y discuss, and ase m p h a s i ze d b y o t h e rs ( R a m a n a t h a n e t a l . , 1979 ; Manabe and Wet he ra l d , 1980 ; Po t t e r andCess , 198 4) , i t is the sur face - t ropos phe re CO2-heat ing, ra ther than sur face heat ing, whichdom i na t e s t he su r f ace t em pera t u r e r e sponse . A s K i eh l and R ama na t han fu r t he r s ta t e , ' t hei nc l us i on o f t he con t i nuum dec reases t he su r f ace - t roposphe re hea t i ng by a neg l i g i b l e4 . 5%' . A m ore r ecen t s t udy by La l and R am ana t han (1984 ) is cons i s t en t w i t h th i s ,s h o w i n g o n l y a m i n o r r e d u c t i o n i n C O 2 - i n d u c e d s u r f a c e w a r m i n g w h e n t h e 1 2 - 1 8 / a mH 20 ove r l ap is i nc l uded .6. A n Exp er im ental is t 's Ap proachIdso (19 82e ) has a rgued t ha t t he C O 2-c l ima t e ques t ion shou l d be approach ed by ' l ook i nga t expe r i men t a l da t a f o r t he r ea l w or l d and ana l yz i ng t hem w i t h a b it o f com mo n sense '.We ag ree, and w e now procee d i n j u s t t ha t m anner .

We f i r s t resor t to a model sole ly for the purpose of ga ining ins ight as to how exper i -me n t a l da t a shou l d be ana l yzed , and fo r th i s pu rpose w e now d i f f e r en t i a t e be t w ee n f l uxesa t t he su r f ace and a t t he t o p o f t he a t mosp he re , such t ha t F (Su r f ) is t he ne t i n f r a red f l ux


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37 4 Robert D. Cess and Gerald L. Potteia t the s u r fa c e , wh i le F ( T op ) is the ou tgo ing in f r a r e d f lux a t the to p o f the a tmo s phe r e .Fo r the 2 x CO~ s tudy wi th the La w r e nc e L ive r mo r e mo de l , the r e s pons e o f the s e f luxe sto the C O2- induc e d c lima te c ha nge is f ou nd to be

d F ( T o p ) - 2 . 2 W i n - s ~ - 1 , ( g a )d T s

d F ( S u r f ) - - 0 . 2 W m - s ~ - 1 ( 9 b )dT,W e ne x t s e e k a ' p r o xy ' c l ima te c hange f o r wh ic h w e c a n e m p loy da ta f o r the r e a l e ar th -

a tm os phe r e s y s te m, a nd f o l lowing Se ll er s ( 1969 ) , Bu dyk o ( 196 9 ) a nd ma n y o the r s s ince ,we s e le c t l a t i tud ina l va r ia b i li ty o f the e a r th ' s a nnu a l c l ima te . B u t f i r s t we e m p loy them ode l a s a t e s t o f th i s c ho ic e , a nd a p p ly ing the s a me p r oc e d u r e a s Ce s s ( 1976 ) , we f indf r om la t i tud ina l va r ia b i li ty o f the m ode l ' s c on t r o l c lima te tha t

d F ( T o p ) - 2 . 0 W m 2 ~ - 1 , ( 1 0 a )d T s

dF(SurO - 0 . 9 W m 2 ~ - t . ( 1 0 b )d T s

Com pa r i s on o f Equ a t ions ( 9 ) a nd ( 10 ) s ugges ts tha t the ' l a t i tud ina l va r ia b i l ity e xpe r im e n t 'a t the t op o f the a tmo s phe r e ( Se l l er s, 1 969 ; B udyk o , 1969 ) migh t ha ve m e r i t , bu t a t thes u r f a c e no t e ve n the s ign f o r the ' p r o xy e xpe r im e n t ' is c o r r e c t . I nde e d , M a na be a ndW e the r a ld ( 1967 ) f ound the s a me p r ob le m in c ompa r ing e mp i r i c a l f o r mu la t ions f o r thene t s u r fa c e in f r a r e d f lux . M or e ove r , the l a c k o f a g r e e me n t be twe e n Equa t ions ( 9b ) a nd( 10b ) i s c ons i s t e n t w i th ou r p r io r i l lu s t r a tion th a t the s u r fa c e r e s pons e f unc t io n , a s de f ine din Se c t ion 2 , i s de pe nde n t up on th e m a nne r in wh ic h the c l ima te c ha nge is induc e d .

Tu r n ing ne x t to a c tua l e a r th r a d ia t ion bud ge t da ta , Ce s s ( 197 6 ) ha s s ugges te d tha tz X F ( T o p ) / A T s = 1 .6 W m - s ~ - 1 e m p loy in g s a tel l it e da ta in c on junc t io n wi th l a t i tud ina lva r ia b i li ty , wh i le f r om L ia n a nd C e s s ( 197 7 ) A Q ( T o p ) / A T s = 0 .3 W m -s ~ -1 , th is la t te rva lue r e f e r r ing to i c e - a lbe do f e e dba c k . The c o r r e s pond in g CO2 r e s pons e r e a d i ly f o l lows tob e H= , ( 1 1 )A T s d F ( T o p ) d Q ( T o p )

d T s d r swhe r e H i s the CO2 he a t ing pe r tu r ba t ion o f the s u r f a c e - t r opos phe r e s y s te m. Em ploy ingH = 4 W m - s f o r a doub l ing o f COs ( Kie h l a nd R a m a na tha n , 1982 ) , Equa t ion ( 11 ) y ie ld sA T s = 3 ~ in e s se n t ia l a c c o r d wi th m os t m ode l e s t ima te s bu t a n o r de r o f ma g n i tudeg r e a te r tha n tha t p r opos e d by I d s o ( 1980 ) .

The p o in t o f th is , o f c ou r s e , i s tha t in the a bove we ha ve f o l lowe d the s a me ph i lo s ophya s I d s o . W e ha ve c oup le d a n e m p i r i c a l c l ima te r e s pons e f unc t ion w i th a mode l - c a lc u la te dCO2 f o r c ing to e s t ima te th e c l ima te r e s pons e to a doub l ing o f a tmos phe r ic CO s .


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A Commentary on the Recent C02-Climate Controversy 3 7 5

7 . C o n c l u d i n g R e m a r k s

A s d i s c u s s ed i n S e c t i o n s 3 a n d 4 o f t h i s p a p e r , t h e a r g u m e n t s t h a t c o n v e n t i o n a l m o d e l es -t i m a t e s o f C O 2 - i n d u c e d s u r f a c e w a r m i n g a r e an o r d e r o f m a g n i t u d e t o o l a r g e a r e s i m p l yb a s e d u p o n v a r i o u s v i o la t i o n s o f t h e f i r st l a w o f t h e r m o d y n a m i c s . A l t h o u g h I d s o h a s c o n -s i d e r e d t w o a d d i t i o n a l ' c l i m a t e e x p e r i m e n t s ' w h i c h w e h a v e n o t a d d r e s s e d ( I d s o , 1 9 8 0 ,1 9 8 2 a , e ) , th e s e u t i l i z e n o n e q u i l i b r i u m o b s e r v a t i o n s a n d t h u s s u f f e r t h e s a m e d e f i c i e n c ya s d e s c r i b e d i n S e c t i o n 4 . W i t h r e s p e c t t o I d s o ' s m o r e r e c e n t c o n t e n t i o n t h a t i n c r e a s i n gl e ve l s o f a t m o s p h e r i c C O 2 s h o u l d l e a d t o s u r f a c e c o o l i n g , w e f e e l i t r a t h e r o b v i o u s t h a tw h a t h e h a s r e g a r d e d a s a s i g n a l i s a c t u a l l y c l i m a t i c n o i s e .

W e w o u l d l i k e to e m p h a s i z e , h o w e v e r , t h a t t h e c u r r e n t s t a t e o f k n o w l e d g e o f t h e cl i-m a t e s y s t e m is r u d i m e n t a r y a t b e s t, a n d t h e re m a y w e l l b e i m p o r t a n t c l i m a t e f e e d b a c kp r o c e s s e s w h i c h h a v e n o t b e e n i d e n t i f i e d . I n s h o r t , w e d o n o t p r e c l u d e t h e p o s s i b i l i t y o f af u t u r e C O s - c l i m a t e c o n t r o v e r s y f o u n d e d o n f i r m e r g ro u n d s t h a n t h e p r e s e n t o n e .

A c k n o w l e d g e m e n t s

W e t h a n k A . J . B r o c c o l i f o r p r o v i d i n g u s w i t h o u t p u t f r o m t h e G e o p h y s i c a l F l u i d D y n a m -i c s L a b o r a t o r y g e n e r a l c i rc u l a t i o n m o d e l , a n d V . R a m a n a t h a n a n d J . T . K i e h l f o r t h e i rh e l p f u l c o m m e n t s o n a n e a r l i e r v e r s i o n o f th i s p a p e r . T h i s w o r k w a s s u p p o r t e d i n p a r t b yt h e N a t i o n a l S c i en c e F o u n d a t i o n t h r o u g h G r a n t N o . A T M 8 2 1 2 7 9 1 t o S U N Y S t o n yB r o o k , a n d i t w a s p a r t i a l l y p e r f o r m e d u n d e r t h e a u s p i c e s o f t h e C O 2 R e s e a r c h D i v i s io n ,O f f i c e o f B a si c E n e r g y S c i e n c e s, U .S . D e p a r t m e n t o f E n e r g y b y th e L a w r e n c e L i v e r m o r eN a t i o n a l L a b o r a t o r y u n d e r C o n t r a c t N o . W - 7 4 0 5 - E N G - 4 8 .

R e f e r e n c e s

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376 R o b e r t D . C es s a n d G e r a l d L . P o t t e r

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W a t t s , R . G . : 1 9 8 0 , ' D i s c u s s i o n o f Q u e s t i o n s C o n c e r n i n g t h e P o s s i b l e I n f l u e n c e o f A n t h r o p o g e n i c C O 2o n A t m o s p h e r i c T e m p e r a t u r e ' , J. Appl. Meteor. 1 9 , 4 9 4 - 4 9 5 .

W a t t s, R . G . : 1 9 8 2 , ' F u r t h e r D i s c u ss i o n o f Q u e s t i o n s C o n c e r n i n g t h e P o s s ib l e I n f l u e n c e o f A n t h r o p o -g e n ic C O 2 o n A t m o s p h e r i c T e m p e r a t u r e ' , J. Appl. Meteor. 2 1 , 2 4 3 - 2 4 7 .

( Re c e i v e d 2 1 F e b r u a r y , 1 9 8 4 ; in r e v i s e d f o r m 2 A p r i l , 1 9 8 4 )

Cess Potter

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