Interdepartmental letterhead December 18 1984 Mail Station L Ext V MEMORANDUM 'f' ' ' ' TO Nuclear Wint lobal Effects Distribution FROM J B Knox fi• SUBJECT The Prep L d Release Statement from the NAS Study -- The Effects on the Atmosphere of a Major Nuclear Exchange f During my visit to Washington the week of December 11 one of our sponsors had acquired the prepared release that was given to each person attending the NAS briefing regarding their new report I am circulating the release to you on this date in that it may be useful to you while you await the full report Mike MacCracken assures me that there are several copies on order so that we will all have a chance to read it From my comments in the margin one can gather that it is my belief the report could have been better However I am relieved that the N AS report is as good as it is I believe that the uncertainties regarding the emissions from forest and urban fires were deemphasized a bit the fact that these uncertainties may be larger than those from early microphysics coagulation and scavenging did not come out JBK clm Global Effects Distribution L R Anspaugh L-453 G F Bing L-19 L C Haselman L-3 5 S-W Kang L-390 J B Knox C E Leith L-13 F M Luther L-26 2 lVl C MacCracken L-262 M M May L-19 C R Molenkamp L-262 J H Nuckolls L- 295 J E Penner L-71 R F Perret L-81 W M Porch L-262 J H Shinn L-524 C B Tarter L-295 E Teller L-4 University of California 11 a Lawrence Livermore National Laboratory •' • • • I' '1 ___ r-- 1 -77 • L I The Effects on the Atn1osphere of a Major Nucle'ar Exchange Committee on the Atmospheric Effects of Nuclear Explosions Commission on Physical Sciences Mathematics and Resources National Research Council NATIONAL ACADEMY PRESS Washinp n D C 1985 • I NATIONAL RESEARCH COUNCIL aD1 c aarnvra AWINUI WI IIIIWCTON D C WIii OfflCI OP THI CNAlkMAN --· In early 1983 the Departaent of Defenae aaked ua to•••••• inforMtion on tbe poaaible ataospberic effecta of nuclear var for•d a caaaittN of apecialiata froa relevant fielda to conduct tbe aaaea nt ftia ia the coaaittN'• final report • uclear var would have cataauopbic effecta beyond tboae tbat aight degrade the earth'• ataoapberer tb our coaaittee euained only one i ut of a large and ooaplex iaaue And even within tbia part the • ·-- --mitt•• vaa aaked to focua only on effecta on tbe atao• pbere and not carry the analy• ia to the next logical atep1 the con• equence• of cbant•• in tbe ataoapbere for life on eartb 'l'bia ia an iaaue tbat ahould and will be addreaaed Tb• eo1111ittee ba• admirably perforaed a taak tbat proved even aore difficult than we bad anticipated had appreciated tbe difficulty of exaaining the acientific aapecta of a aubject tbat-for anderatandable rea• on• --provokea atrong eac tional reactiona An equally foraidable taak bowever vaa tbat of oopin9 with profound 9apa in exi• ting knowledge 'l'be unfortcanate but unavoidable fact la tbat n though we are 40 year • into tbe nuclear age aucb of the basic inforMtion nNded to tbe likelihood and extent of cilobal ataoapher ic con• equencea of a nuclear exchange aiaply c k - · ' ' Aa a reault tbe 001111ittee baa been unable to prcwide tb• j unqualified finding tbat we all aight vi ah to have in order to aaa that any nation'• deciaiona about nuclear farce• are not Mde in ignorance of their true oonaequencea a••••• under th••• condition• tbe oa aittff deteralned it oould beat aerve by riaing exiatin9 knowled«Je by drawing the partial ooncluaiona nece•• ary qualificationa tbat are aupported by data by clearly deac ibing tbe nature and extent of uncertaintiea and by indicating where tboae uncertaintiea aight be reduced tbrougb furtber reHarcb a cau• e additional knowledge aight well alter our current anderatandin9 tbe report can only be Yiewd u an interia atateaent lleverthelea• we believe it can help tbe aclentific co•u nity and tbe world'• governaent• advance tbe tiM when we can adequately anaver a queation of aurpaaaing international illportance Frank Pr•• ChairMn N M1DW IISdat CIQICIL 111NE llfJNCIM OfllATMCN ll fC f Of1NE Nld'ICIIW AICAIIIM ' Of scmasMID 'IHI NAlDW N NlfJl' Of INCINIWNC 'lll IDVI CXM1UMN1' Ml onuCIIGMIIIA'l'l0N 1• -·· Committee on the Atmospheric Effects of Nuclear Explosions GEOROE F CARRIER Division of Applied Sciences Harvard University Cambridae · · - achuem Cbairmln '4M J MORAN Vice Admiral USN Rct Los Altos California Vice Chairman #w BIRKS Depanment of Chemisuy University of Colorado Boulder Colorado llOBERT W DECKER U S Oeoloaical Survey Menlo Park California DOUOLAS M EARDLEY lnsutute for lbeoretical Physics University of California Santa Barban California JAMES P f'RIEND Depanment of Cbemisuy Drexel Univenity Philadelphia Pennsylvania ERIC M JONES Los AllmOI National Laboratory Los Alamos New Mexico JONAllfAN I KATZ Depanment of Physics Wuhinp n University St Louis Missouri SPUROEON M KEENY JR • National Academy of Sciences Washinpon D C CONWAY B LEOVY Depanment of Atmospheric Sciences and Graduate Propam in Geophysics University of Wuhinpon Seattle Wuhinaton CONRAD L LONGMIRE Mission Research Corporation Santa Barban Caliton s MICHAEL B McELROY Harvard Center for Eanh and Planetary Physics Harvard University Cambridae Masslchuse WJUJAM PRESS Depanmem of Amonomy Harvard CoUeae Observaaory Cambridae Massachuem r lC P RUINA Depanment of Elecaical Eqineeriq Musachusem lnsurute ofTechnoloSY - mdse Muslchuseus ·_ 'E M SHOEMAKER U S Oeolosical Survey Flqstaff Arizona u - iRJNO SMITH Vice Admiral USN Rec San Dieao California O BRIAN TOON Ames Research Center NASA Moffett Field California IJCHARD P TURCO R D Associales Marina del Rey California S '6 LAWRENCEE McCRAY PEOGY POWERS '' y •• • --· Contents Summary and Conclusions I Recommendations for Research IO 3 1be Baseline Nuclear Exchange 13 4 Dust 17 5 Fires 36 6 Chemistry 7 Atmospheric Effects and Interactions 1 n-- Use of Climatic Effects of Volcanic Eruptions and Extraterrestrial Impacts on the Eanh as Analogs 174 Appendix Evolution of Knowledge About Long-Tenn Nuclear Effects 185 Index 189 ix • 1 Summary and Conclusions 'he Coa ittee on tile Ataoapherlc Sffecta of IIUclear SXploalon• 1 ·' •••ed tb• followin9 claar9e1 1 deter • ine tile aanner 1n wbicb the ere of tbe earth would be • odlfied by a • Jor eacban9e of L - u weapon• and lnaofar a• the current atate of knowled9e and 1111der1tandin9 per• ita tl•• a quantitati•• deacription of tbe mre illportant of the cban9ea and 2 i-ec0•1nd reaearcb and exploratory work appropriate to a better underatandln9 of the queation be coaittH waa not uked to and did not tb• related but diatlnct que• tiona of tbe extent of radioacti•• fallout or tbe blol09ical or aocial iaplication• of poatvar atm• pheric aodification • cent calculation• by different inve• ti9atora •utv••t that th• cUaatic effect• froa a Mjor nuclear exchan9e could be lar9e in acale Altbouth there are enoraou• uncertainti•• inTol•ed in the calculation• tb• coaittH beliff•• that lon9-ter• cllMtic effect• with • -Yer• laplicationa for tbe bioephere could occur an• H effect• abould be included in any analy• i • of tile oon• eque - _ nuclear var • Olfe'ler the coaittH cannot aubacrlbe vitb contidence to any • pecific quantitatl•• conclusion• drawn flea calculation• baaed on current scientific knowledt•• 'be e• tiMte• are necea• ar ily rough and can only be ued aa • neral indication of the 1eriouan••• of wbat •ttbt occur r- apU e the early atate of under • tandin9 of Mttera the - 11ty of aevere degradation of tile ataoapier• after a Mjor · excb n9e la of auf flcient national and international concern tb a aajor effort to narrow the scientific uncertainti•• abould be ti•en a bigb priority •ddr••• th••• It la wifely ancSeratoocS that any • Jor nuclear ucbant• would be aeci 'llpaftied by an enoraoua allllber of iwdiate fataliti••r aeverthel•••• • auch lar9er fraction of the buaan population would aurvi•• the iaaedlate effecta of a nuclear eacban ftia atudy current knowledt• about tile nature of tbe fbyaical - uG111N11t the • urvinr • would bne to face eddr•••• 1 •• 2 • - -1 ✓ · ft• rNliutl• tbat a auclear eac bant• would N ac c c apan1 cs t y tbe _ltlon lato tlae ataoapber• of lar1• aaounta of rtlculate Mtter la • t IIOwffer lb• •utt••tion tbat tlae uaoclate4 attenuation of eanlltbt aipt N eo ••ten•l•• •• to cau• e en•r• drape In au face air telllperatu r•• and otber cllMUc effecta la • - tbat ue far racwed frca tar t •••• 1• of ratber recent ocqln bat perception - baa 1rown out of a nuaber of recent me• t19atlona Crutaen and airka 1112 recovnised tbat tbe -- unt of ADke frca tbe fir•• ltnlted by nuclear blaata could be of crucial iaportance and Alwares et al 1910 bypothe• ised tbat tbe •••lv• • peel•• estinction• of 15 allllon year• a90 wr• put of tbe afteruth of tbe loftlnt of quantltl•• of particulate• re• ultlllt frca tb• collialon of a lart• •teor with tbe eart b Otber • bave reooplsed tbe • lallarlty betWHn tbe Alvares duat bypothe• la and tbe effecta of nuclear var • H AppencUa 'lb• conaequence• of any • vcb chant•• 1n ataoapberlc • tat• would bav• to be added to t be already • ober ln9 li• t of relatively wll•under • tood conaequence• of nuclear var lacludln9 proapt radiation blaat and th•r•l effect• abort-tera ianal radioactive 1 -••• and tbe fallout inadequate •dical attention for aaar•f ir l0n9•t•r• blol09lcal effect• of 91 obal r - apber le con• equence• urply additional probl- 'Cha - • - · t19ated by prior preparedn••• and that are not in baraony with any aotion of rapid o• tvar re• toration of • ocial • tructaar• 'Ibey a1ao create an entirely new tbreat to population• far reaoved frca tar9et areu and •utt••t tbe poa• lbility of additional ujor ri• ka for any nation that it• elf initiate• u• e of nuclear weapon• even if nuclear retaliation • bould acaahow be llaited oc •••b• • tudy tbe OC11111ittN fir • t oonatructed a baaelln• war acenarlo ude up of a •• uaptlona ooncernln9 tbe nataare of tbe weapon exchange 'be baaelin• acenarlo • H Chapter 3 for treater detail va• Hlected ao aa to be repreaentatlve of a neral nuclear vara one-balf-about 1500 aegatona Nt --of tbe eatlaated total world ar • enal would be detonated Of tbla 1500 Nt would be detonated at 1round level Of tbe other 5000 Nt tbat IIOllld be tonated at altitude• cbo• en ao a• to uaiais• blaat daaat• to atructure• 1500 Nt - would be directed at ailitary econoaic and political tar9et• that '' oolncidentally 11• in or near about 1000 of tbe lar9eat urban area• • 1 ' 7 All uplo• ion• would occaar betvffn JO•• and 70• • latitude 'lb• OGllllittH alao c bo• e on tbe buia of a r • i • of tbe ·•• aclentlfic literataare a Ht of buellne pby• lcal pu-t•r• to u• e in calculating tbe effect• of tbe bueline weapon acbM19 •cb bUelln• -r ter wa• cbo• en to lie well witbin tbe apectr• of • cientlfically plau• ible value• ••lue• 1n tbe •lddl• rante• of plau• ibillty belnCJ preferred flier• are tbrN iaaedlate oon• equence• of a ujor auclear eschUCJ• tbat could 11••• a • iplficant iapact an tbe aub• equent etate of the 'fO provide a fraaework for it• i - C1 · •• J • at- pbere LU lalMlllta of dlaat ooa1• lie lofted laltb Sato tb• ataoapbere lu llr• ODUld be lalttated and lart• UIDllftta of le abeal 8J1Kl•• ooulc1 be relHNd _ of tb• key - - t • r • u • iilad foe tb• buellae cue follow · · fte uount of _t Cbapter t tbat IIOllld lie depoelted la • • •trat Npbere la related to total ft• Galla - - - • _1 bat --•--total aoant lofted la 0 3 terqr- 1 trv • 10 9 • 106 •tric_ton• per - aton detonated atpt -rcent of tb• - •• of duat IIOllld ·'be of • ubaicron abe wblc b r 1n J t for long period•• ne 1500 Nt 1n 9round bur • t • vould rai• e about 5 of aubllicron du• t o Sato tbe atratoepbere wbere it could rulde for • than a year rz -« « _ Dmint tbat tlM the aolar radiation tbroup that duat and into the lower atao• pbere IIOUld be reduoed ft• analyala of fir•• and amke la GD11pl•• Chapter 5 ft• 5000 Nt of air bur • ta vould initiate •ltoroua fir•• 1n cit le• and fore• t • wer •••• wber• the theraal radiation incident on ODllbu• tlbl• Mt er ial • • 20 calorie• per aquare centiaeter cal ca2 or treater a auaber well 1n nee•• of tbat known to be adequate to lplt e th• fuel• at band In the cit y-• cale urban confla9ratlon• tbat would enaue tbe buelin• a •• uaption 1a tbat three-quart er • of the ooabu• tlbl• aaterial s 4 in affected area• would be conauaed arly ocaplete con• uaf Z iO of - ·•tible aater lala 1a typical of large clt y-wide fire• for lfbicb e aYailable A1th 9h uny of tbe urban firea vould probably • •• ' beyond tbe 20 cal ca pit ion aone no additional fuel burden froa tbat • preadln9 1a uauad 1n tbe baaellne caN · Of tbe aaterial that burned 1n cit lea tbe ba• elin• ca•• u • ua• that • oae@peroent liaited data • u99e• t •aluea lying betvffn 1 percent and 6 percent - lo l e1-a IIOUld be converted to aaoke particle• in a range of • ubalcron aise• we tbat would ab• orb and • cat ter • unllpt ••ry effect lYely Certain proce•••• aay bowner diainiah the optical effecta of tbe - at tbia at ate Duzint the burnin9 of tbe urban and or foce• t fire• the ••ry fine uolte partlclu would under90 • oae coa1ulation in tb• rialn9 pluae O er region• wbere the ubient 1round-lnel baidlty vu hip tbe oonden• atlon of aol• ture entrained in tbe pluae aould incorporate • cae of tb• DDke flier• la little eapirlcal evidence t o a1199e• t ezten• l•• aca•en9in9 of tbe DDke by tb••• pcoce••••• but in 8 i o ' 'a tbe bueline ca• e 50 percent of tbe • --e i • uauad to be r-- ed froa tbe pluaea of urban f ira 1n tbla aanner · On the bula of nailable inforMtlon on pl dynaalc• it ia auuaed tbat abort ly after depo• ltion the amke froa the enaable of fir•• would be alfocaly dlatrlbuted ••rtically per unit beltbt betvffn o ad I lal oi er the entire affected uea tbe local ••rtlcal diatr lbutlon waa1d be nananifora • becau• e the altitude• of tbe • --e pluae• would TUY froa one fire to another and would alao yary with tbe ••• dependent lntenait y of tbe fire Al though under apeclal •teorol09ical circua• t ance• • oae of tbe DDke • itbt be depoalted at altitllCle• aiplflcant ly biper than t m tbl• effect 1a ipored in tbe baNllH ca• e Initially and for • cae wek• tbe aot• would bne a wery IICIIIUDlfoca bor i1ont al dlatr lbatlon but IIOUld be dl• tr ilMated tbroupout tb• trop apbere of tbe nortbern taperat e SODe - •tanute• ••• • • I • • • a Ctian of altr01911 •idea fr• tlae ncleu olouda into tbe k • wer atmapa•e would lead to• 1etian of t be oaone 00111111 wbicb wuld N rNtored in about 2 -ra Cbapter I Ille atmapaerio upllcatlau of tlae NNU ne and of tlae reaulta of otber troupe• analpea are ICeHftted la Cllapter 7 ibe cmalttee e cta tlaat aolar radiation paaain1 tbroatb tlae · atratoepberic layer of nuclear duat would be abeOrNCI la tlae upper r99iona of tb• amke layer ft• aaoke layer would bMt ap and alnce little aolar radiation lflOllld reach lower 1ffela tlae air ••r land aurfaoe• would 0001 Altlaoutb a few type• of natural ffenta can pro ide au1illally relwant infor•tlon on upecta of tbe pcobl• a1ao Cbapur I • ucb of our underatandint of the ataoapberic reaponae to larte UDUnta of airborne particulate• will aaae froa aodel aiaulatiau • odela are •alldated within relati•ely -11 natural •ariationa ao their predict •• capability la li• ited for tbeae lar1• perturbation•• Only preU ainary eatiaatea can be •d• of tbe rate of apreading of particulate• over initially clear latitude• and of tbe rate of reaoval of particulate•• 'lb• duration and •CJnitude of at• oapberlc effecta would depend on bow lon9 the abaorblng particulate• tned aloft Tiler• ia eapecially lar9e uncertainty aaaociated with lon9•ter• r- a1 proc••••• for aac ke that •ur•i•e• tbe early acnenginf £ow-altitude precipitation proce•••• • igbt r_ • the low-altitude aaoke tlaat below • kll the nor • al ran9e for aoke rather efficiantly aut at bi9h vJ l altitude• t be increaaed air tuiperature and the low 11•1dity could 11 • J lead to a re• cwal rate in tbe _ to t-ka ranv• that would be alower Osl- -i t ban the r1110Val rate in today'• tropoaph t• lfh• ba••llne aa• uaea 1 that re• oval rate• would be at leaet ct ' - · ··· _ -wal rate • in the lower ataoapbere below 5 ka but wo lower tban nor • al in tbe upper tra oapb•r• 5 to 10 Im with abou one-balf of 1 the initial particulate• rlllOVed froa th• lower ataoapbere in 3 a ya and frOII tbe upper ataoapber• in JO daya • It la •likely that tbe average reaidence tiaa for poatwar aot• would be • uch lua tban tb••• ' ••luea and quite poulbl• that tbe •an reaidence tia in the upper tropoaphere would be longer It ia boped that tbe aa1111ittee•a buelin• cue will provide a UNful point of departure for tboee who wiah to identify and tbe I I eDYiron• ent tbat would prnail following a aajor nuclear eacbange 'ft s z - 8 - ft••• u•••• • •Jf the aaoke particle• acquired electrical c barge• tlae ooa9ulation and • -Dke reacwal tlaea oould be affected aowe er tber• ia no evidence froa 1ar9e blatorical fu•• tllat electr1cal actl•ity lnten•• enou9b to be obaerved waa operati••• rurtberaore tiler• la no ffidenc• t bat tbe aoaetiaa large and •lalble electrical effecta in inten•• natural ffant• ••••• tornadoea and YOlcanoea influance tbe clynuica of tbe • tora bnlnt ao reliable bula on 11biab to do otberwiae tbe ooaaittN lluL •retarded potential electrical effectL ft'j f 'LJ _ 2 I • s • •r • cleu I r • tlala bclef tlMcrlptlon of tile bueliae oue tbere are aany toiat• ill • • analyala at •lab tllere ia a wide rant• of -r-ter • a l - tllat • • oan• t • tent wltll tbe but current act•tlflc uc 1 e any •tt te of tbe werall ataoepber le rnponae will s-o1 CCialCl andiftt of t le effecta of t leae uncertaiatiea Olwiou1y calcu1atlou •de under tllne oondltlon• cannot be r•d • a aclentlfic· predict of t le effect• of a nuclear uchan9e ratber tbey repreaent an inter • te froa wblcb the reader can infer ✓ _ thing of tbe otentla Hr ouan••• of tbe ataoapberic degradation tbat al pt ooeur lcae rniewer • of earlier draft• of tbia report cautioned tbat ffen tb• aoet qualified naerical re• ulta coduced under th••• condition• oould N alainterpreted and aoae •utte• ted at at pre• ent t le only a Ufically ••lid oancluion would be tbat it la not at tbia tille - e to calculate tbe ataoapher le effect• of nuclear war t'b• c o CH bel lne• bowffer tbat an appropr lately qualified tc•liainary quantitatl•• treataent of tbe cobl• ia warranted on two tround•• •irat ti•en tbe enoraou• buaan atake• tbat •Y be iaYol•ed lt •Y not be ad9i• able to wait antll a • tront acientlfic ca•• b• been uaeat led Nfore ceaenting tentati•• reault• r tbere i • a danger tbat J re ort tbat reached no conclu• ion• at all would be ai• conatrued to be vl refutation of tb• • cientific ba• ia for tile •utt••tlon tbat • ffere ataoepherlc effect• are po•• ible lecond a quantitati•• approach to tbe cobl• la tbe beat way to enaure tbat all taportant factor • are ayat tically con• idered and quantification belpa di• tingui• b the iaportant factor • froa the 1••• taportant one• in tile a erall analyat a lucb re• ult• are nece•• uy to the orderly allocation of reaource• to the aoet pertinent re• eucb que• tiona ft• findint• of tbia report depend in rather luge •a•ur• an a atill llaited body of acientific inquiry acae of wbich la not yat fully docuaented Attention to tile aubject la ao recent in fact tbat 80lle of tile underlying analyaia bu not yat undergone the r rffiev oce•• tbat precede• pablication ill aoet scientific journala be reader aboold appreciate the _aibility tbat further r-arcb rll iaYalidate •-- of tbe tiaate• diacu• aed in tbla report a - 1tly u 1175 wben tbe tional ••uch COUncil report Lona•ftr• llorldvlde Sffect• of Multiple •uclear Detonation• appeared plau• 1bl• weapon•• acenuioa differed aiplflcantly froa thoae envt aaged today ud tile crucial iaportanoe of fir•• and aoke bad not tben Men recotniaed It follon tbat tbe findlnt• ceaented in tbl• report differ fr• tllloee of tile 1115 report Jwthermre t be -nuiTe uncerta atiu ill tbe data ad tbe liaited Yalldlty of tile at aoaJ ller le aodela IIHd to date blply tbat acae future atudy oanducted it a tiM vben tile data and IIDdela bffe Men UlfCC9ed oould coduce I 4111lta lfferent anal ya•• and oanclulou It la _aibl• tbat iapcwed rJeJ aderatancUn1 of • OM aecbaniearly acn entlnt oould ao 0 aff tbe rMulta t bat t be aaoapberic defradatlan would be allawD to_ - N wuer tban tbat MtiMted ill t be baHllne caae but the •anoertaiaty alao Mk• it a clear -aibility tbat tbe em b ODll14 Aa I I I •pon• C••••• •• I I troclaoe a depadatioll t llat WIil ci N tr•ter t un ad IIOllld 1ut 1an r tllaa lllat Ntialted in tile laueliae la llllact1 tlle -lttee•• fladlnt• are clearly ad tlcally of • iatarill allaracter - A Yitorou r-• -rcb effort i • DOif Meded llffert lle1N• ON - ct tut lonl-tar• auclear effect• •111 be abaraotulud wltb 91 t ceclaioll • oanfldence in tbe aut year •• 11• 11J rtalntle• cannot be narrowecS becau• e 1 bey depencS an buaan decialau lbat can be Ude or cbantecS lont after any articular pcecUction bu been i • auecS • • • include for exaaple tbe total yield of tbe ucbant• indi•ldual warbead rielda tbe Illa of tarteta tbe Ilia of altitude• at· llbicb tbe ttur • u would occur and tbe auaon of tbe year in wb1c b tb• excbant• would oocur In addition tb•r• are olwiou llalta t o t b• • • of larte-ac al• esperillenta in tbia field and tbe wolutlan of at mapber le aodela will r91111lre ac ae tlM Nany • ipUicant ancert alntie• llowffer can be narrowed by furtb•r • tudy In articular tbe beipta to which • mite ia depoalted 1n clty-acale fir••• tbe early aok• reaowal by ooa1ulation and oanden• ation in t be fire plu• e tb• utent of oontlnued baoyant rialn9 of • un-beatect opaque clouda and tbe ctynaaical re• pan• e of tbe ata apbere fir • t to patchy 111th•altltude aol r abaorptlon and tben to tbe beatlnt of aore broadly diatr ibuted but • till lleavy aoke oc er receiwect only acatterecS and recent attention cannot la•• 00aCUJBl0118 'be t•n•ral conclu• ion tbat tbe oaaaittN dt_ t• t- i- 1 · · • · • • tbe followiftta • Mjor nuclear IIOUl c -• - · t a of UIOke fin• d u l r a b l e cb•ica a •• ant• poa -ateoepbere ft• ti could re• ult In tlrw- 11 p- urbatlcna of tbe ateoepber _ ___ er a period of at 1 t a f ka • tiMtion of tbe amunta tbe wertical diatrlbatlau and tbe • ub• equent fate• of tb••• Mter iala Jffol••• larte --rtalnU e•• hrtberaore accurate detallect aocounta of t b• re• pan• e of tb• ataoapbere tb• recSiatrlbution and r • l of tbe depo• itlona and tbe duration of a wreatly de9raded mwlranaent 11• beyond tbe pcNent at ate of knowledt•• lleYertbel•••• tbe GC1111ittee finda t bat an1- ane or • ore of tbe effecta 11• MU tbe 1••• • ever• •d of tbelr uncertainty rant• or NM • ltlt•tint effect tau been orerloollecS tber• ia a clear poealbillty tbat wrut portion• of tbe land areu of t b• aortbern taperate aone and -rbape a lart•r • -pent of tbe planet oould be • fferely affected toealble iapect• include Mjor teaperature reduction• C Uticularly for an eacbant• tbat occur• In t 11• • - r · ·ia tlnt for ta witb aubnorMl taaperature• peraiatlnt for • antba lfbe illpact of tb••• uaperature reduction• and auociated Mteorolotical cbant•• an tbe • uniYint populatlan 11141 • tb• bioapber• tbat • upporta tlle • urYiYDra oould be -e and •••••• careful independent atudy IIDl••• •• A • I a re finlti•• • tatwnt can be •de anly • • aany of tbe pcertaintie• llff• been wrowed 1 llben tbe wller acale penaaena are lpetter ader • too11 1 and llben ataoepberic re• e e aodel • bne been li truct ed and llffe 199Pirl4 crt4lbllltY for t be parwter - •• of ___ pbenoaenolon ••· oa111ittN al• o dr-• eral are • cific oonc lu• iaua 1 In an utenai•e auclear exchant•• explo• ion• orer urban•••• ion• are an iaportant upect of nuclear warfare tbat lane GIily recently been reootniaed l'Or tlle jor 1500-Nt nuclear var con• idered bere fire • oould releaH - • be aaount• of aa tke into tbe tropoepbere orer a period of • few daya llucb of tbe uoke • i9ht be racwed by •teorolo9ical proc ea• e • witbin H9eral ka dependin9 on feedback · t• but aipificant amunt• aould _in for HYeral aantb•• · · it• tenure in tbe ataoepbere tbe aok• would 9radually apread ecoae • ore unifor• ly diatrlbuted over IIUCb of tbe aortbern c apbere altbou9h - - patchin••• would be likely to -rai• t Litbt 1 e1• could be reduced by a factor of 100 in region• tbat wre ered witb tbe initial b•i• pherlc nera9e aoke load c au• ln9 int-• e coolin9 beneath t be particulate layer and unu• ually inten• e beating of tlle apper layer lbile lart• uncertaintl•• currently attend t be e • tiaate• of a• ote - • i • aion• and of tbeir optical and pby• ic al aon• equence• tb• baaelln• cue iapli•• • ff•r• ataoellberic can• equenc ea 2 lfbe production of amke fra• fir••• ud tbe iaplied effect• on tb• at• o• phere la • me directly linked to tbe eatent of detonation o er urban area• tban to tbe avgregate yield of a nuclHr •xcbancJ•• ft• indu• triallaec nation• of tbe world bne concantrau b pro ortioa of tbeir reeource• and ocabu• tlbl• fuel• in th '9l - _ or tbe central area• of tllelr lar9e citiu any war acenario tllat • ubjecta tbeae city oentera to nuclear attack ffen ane aployincJ a uy -11 hactian of tbe ui• tint nuclear ar • -nal oould generate aearly •• aucb aoke u in tb• 1500-llt buellne war ecewio 3 ft• cliaatic illpact of • oot la aenaiti•e to it• llf•U• in tbe -rtu rbed ataoapbere and tb• anifor• ity of lta diatrlbutton lifeti• e of • oot l• biply acertain particularly 111 tbe utper troposphere ft• -rturbatian ltaelf wuld pEoduce • ffer• liev effecta any of wbicb oould tend to incrH• e tbe rHidence tille of tb• aoot Altbouth tlle lofted • oot and du• t wou14 rapidly apread around t be latitude band of lDjectian tbe diatributian oould be unnen for a eral aantb• wltb aontlnent-• ia• patab of 1 aer and greater denaity tutlalllarlJ near tbe tb•n edv• of tbe affected aonea • 111 tile buellD• auclear war aoew lo lnandreda of teravr- of J duat i ouJ 4 be ia ec ted into tb• ataoeJb•r• ho• aurface detonatlou A eiplilcant fraction of tbe dut aonaiatint of particle• vltb radii 1 - tban one alcran 1 11• would be expected to _111 aloft or metba About one-balf of tlleH autlllic ran puticlu would be injected Sato tbe atrat oepaue and would pEodw e acae long-tar• reductioD of ••litbt at tbe eartb'a • urface n• after -e and 4u• t at 1olMr altit ldea wre iMIDfed ftia atrat oeJberlc duat alone would 1-4 to and fore • ta wuld ipite aany lar9e fir••• Na •• i•• aaoke • i•• ••Y ·· i• •• • f J C u _roeptlble recluctiaU ill anrA9e lipt illtenaitiN 111d oontinental - r a m • lfOUlcl fall •uu rably ID a plaualble aoturio tllat illnln• mre troun4 bmat attack• atalut ••ry laarcl mteta tban • • - a a d ill Ille ueliae cue Ille - u»ie effecu are ••fw _ -- ua1 Jarver s It la DOt aaalbl• at 1111a tiae to Ntiate t lle IID• t frobabl• nerate teaperature aban1e• at tbe aarfaoe aaue4 a aa »ke and 4uat - _ lofted in Ille bueU ae cu•1 nor would auc b a •inll• •al• nen 1f ·' nallable •anlntfullJ cribe tbe •ltuatian JD addition t o tbe lar anoertalntiH in aany of tile critical Jbyaical ar-ter• and tbe inber•t llaitatiana of tbe aodel• nallable tor -- uter •laulatlou tbe a•allable oalculatiou reflect wide ••aaonal and -otr•Jlbioal difference•• llaoent weneral circu lation mdel a1aulatian• tbat inoorporate alapllfyin9 uaaptlana lndloate tbat a uelln• attack durin9 tb• auaaer alpt clecr•u• •an oontln•tal t eaperatu r•• in tb• Dortbern teaperate son• by u IIUCll u 10• to 2s•c wltb teaperature• alcn9 tbe couta of tbe ocntlnenta decreaalng by aucb 11er uounta In ocntrut an attack of tbe • - ala• during tbe winter according t o tbeae aiaulatlona algbt JCoduce little cbante in t aperature in tbe aortbern teaperate • one altboup tbere aould be a algnlflcant drop tn teaperatur•• at axe aoutbern latitude •• •• 99 nltro n mrldea clepoalted in tb• atratoaJbere by nuclear detonationa would reduce tb• abundance of o• one tor tbe 1500-tlt nuclear war tb• nortbern b•i•Jlb•re oacne reduction ooulcl beccae •ubetantial 8fteral aantba after tbe war tlMt•• baaed on curret atrat oaJberic atructu re •une•t tbat tbe uount of osane recl11ction woulcl c1ec reue by one-half after about 2 ear• _ 6 t - of auillll• oscn• reduction tbe blol091cally effect· uaing tbe mlA action apectra at tbe tr · - ly one and one-balf tiae• tb• nor•l levela lnitiaJ l1 b P'••ence of duat and DDke article• in tbe atao• Jlbere voulcl ccwlde a •••u re of protection at tbe aurface fr• tbe enbanced ultrnlolet radiation 1111• JCOtectlon would 9radually dlainlab u tbe article• Eellewed 7 ftia atudy bu oonoentrated on tbe poaalbl• effect• tbat a D11Clear war oould bne on tbe aortbern b•i•Jb••• ciMrUy witbin tbe • id-latitude region Jo•• t o 10•• ••r• tbe nuclear excbange would be oancentrated It 1a puticularly difficult t o - - · tbe potential effeeta of tbe buellne war on tbe ataoapbere of tbe aortbern tropica •d aoutllern balallb••• ltbougb aoutbern b•iapbere effecta would be aucb 1•• utenai••• aiplficant uounta of duat and amt• oould drift to •d acro• a tbe equator u early u a few week• after a nuclear _ a lar rate of tranaport acroaa tbe equator dr i•• by laeat Dt in Ille debrl• cloud cannot be ruled out ladNd auch bMting-enbanced croaa-equator lal circulation bu been found for 8JC ln9 •d auaaer aantba in oaapater ailllllatiou • I laM Jeebiatorlc nlcanlc eraptlan• and blpacta trca estraterreatrl al bodi•• bne releued ener9I•• oozreQC1Ddln9 to level• tbat would be releued in a •jor nuclear excbante and •r bne lofted • u•l•• UIDUftta of duat bowffer neltber type of • • t ca idea a • Mf11l direct aNlot to tbe nuclear cue becauae Hit bu type llwol•ed tbe roductian of bl ply abeorbing • oot articl•• IWtberaxe tile '· i I -au--• • atmelb•rlo oaa• of cablat oclc utaral ta of - - e ca ortiou are IIDt DDlfll an s IMir effects • tlae foe1il reaord tf ay llffe not _ 80Ulbt ill •Y aptaltlc way ooordiallY •allable kaawledge about p alalatorlo 90loanic and illpact ff•ta ICWide• Hitber aupport DOC refutation of tbe -aitt N'• ODDCl•Sana -· All calculatiou of tbe at mepberic effect• of a Mjor aaoleu - I wr require -ntltati•e uauaption1 about aoertain fbplcal r4e · -r-t•ta ID uny • - • wide ranp1 of ••lue1 are aclentifloally •edible ad tbe werall reault• depend •t•rlally on tbe jss S' cllOlleft 1W of tbeae unoerta1nt1•• •Y be reduced by furtber eapirical or tbeocetic al r•earcb but otbera will be difficult to hi reduce ne lar r unoerta1nt1• include tbe followin91 a aae 4111antlty •4 abaorption pcopertie1 of tbe aote produced in lart• L f UNJ b tbe initial diltl ibution in altitude of DDke prodlaoecS 1n ryv rr - l a 1 fir••• c tbe aecbanlaaa and rate of early • cnent1nt of DOt• - J rw rca fire plaea and a9in9 of tile amt• 1n tbe flr1t few daya 4 tb• v nduced rat• of •ertlcal and borlaontal trauport of aok• ancS dut in µ N tile upper tropoapaere and at ratoapbere tb• r•ult1D9 perturbaticna nJl1 1 in ataoepberic pcoce•••• 1ucb u c loud for•tion pceclpitation - atoraln•••• and wind pattern• and f tile adequacy of current an4 cojected ataoepaeric re• ponae aodel1 to reliably pcedict abant•• lbat are cau• ed by a --•l•e bith-altitude and lrretularly 411tributecS injection of particulate •tter 'lb• ataoepber ic effects of a auc1Nr em bant• depend on all of tb• for- oint fbpical proce•••• a tbzoutb e ad tbeir altiMte calculation ii furtber 1ubject to tbe ucertaintie1 inbuent in Cf •al••__ --- ••Y v jf • Al••••• L w •• ••••• I' ·aaaro ad •••• IUcbael 1910 szuaterr•t rial cau• e for tb• cretaceoua-'l'ertiary enlnction lc ience 20111095-1101 cratsen t J and J w auk• 1112 fte ataoapaere after a nuclear wars 1W11itbt at noon Allbio U111 -12s • ational earcb COUncil 11'75 Lant-Tera IIOrlclwide Sffecta of Nultipl• 11uclear Detanationa wau1n1tan D c • ational AcacSelly of lc ienoea ••pana '• u