国会授权的开展操纵太阳辐射研究的报告（英文）-白宫

CONGRESSIONALLY

MANDATEDRESEARCH

PLANANDANINITIAL

RESEARCHGOVERNANCE

FRAMEWORKRELATED

TOSOLARRADIATION

MODIFICATION

JUNE2023

TableofContents

AboutThisReport 3

SuggestedCitation 4

AbouttheOfficeofScienceandTechnologyPolicy 4

ExecutiveSummary 5

PhysicalAspectsofSolarRadiationModification 5

DevelopmentofScenariosforSolarRadiationModification 6

SocioeconomicandEcologicalOutcomes 6

InternationalCooperationonSolarRadiationModificationResearch 7

ResearchCoordination 7

I.InitialResearchGovernanceFramework 8

TheStateofKnowledgeandCurrentExecutiveBranchAction 8

GoverningResearchResponsibly 9

InternationalCooperation 9

II.ResearchPlan 10

Introduction 10

SectionA.PhysicalAspectsofSolarRadiationModification 12

SectionB.DevelopmentofScenariosforSolarRadiationModification 24

SectionC.SocioeconomicandEcologicalOutcomes 27

SectionD.InternationalCooperationonSolarRadiationModificationResearch 39

SectionE.CoordinationofFederallyFundedResearchintoSolarRadiationModification 43

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AboutThisReport

ThisResearchPlanwaspreparedinresponsetoarequirementinthejointexplanatorystatementaccompanyingDivisionBoftheConsolidatedAppropriationsAct,2022,directingtheOfficeofScienceandTechnologyPolicy(OSTP),withsupportfromtheNationalOceanicandAtmosphericAdministration(NOAA),toprovidearesearchplanfor“solarandotherrapidclimateinterventions.”

TheCongressionaldirectivealsorequeststhatOSTPdevelopa“researchgovernanceframeworktoprovideguidanceontransparency,engagement,andriskmanagementforpubliclyfundedworkinsolargeoengineeringresearch.”AninitialResearchGovernanceFrameworkisincludedinpartIofthisreport.ThisinitialframeworkprovidesimportantcontextfortheResearchPlan.Whilekeyconceptsintheframework,suchastransparencyandinternationalcooperation,arereflectedintheResearchPlan,theResearchPlanitselfdoesnotfocusonissuesofresearch

governance.

Thisdocumentfocusesonatmospheric-basedapproachestosolarradiationmodification(SRM),specificallystratosphericaerosolinjection(SAI)andmarinecloudbrightening(MCB),followingtherecentandextensive2021NationalAcademiesofSciences,Engineering,andMedicine(NASEM)report,ReflectingSunlight:RecommendationsforSolarGeoengineeringResearchandResearchGovernance.1Alsofollowingtheapproachofthe2021NASEMreport,thisResearchPlanmentionscirruscloudthinning(CCT),eventhoughthisworksbyincreasingoutgoingthermalradiationandhenceisnotstrictlyspeakingSRM.ThereisrelativelylittleworktodateonCCT,andthisPlan’streatmentofitreflectsthatpaucityofknowledge.

ThisResearchPlandoesnotconsiderspace-basedapproachestoSRM(commonly,“mirrorsinspace”),norlocal-scalemeasurestoincreasesurfacereflectance(e.g.,“whiteroofs”).Thefocusonatmosphericapproachesalsofollowsfromtheirgreaternear-termfeasibilityrelativetospace-basedapproaches,andthegreatergovernancechallengesofatmosphericapproaches—whichinherentlyhavesignificanttrans-boundaryimpacts—relativetobuilding-scalealbedomodification.

Considerationofbothsocietalandscientificdimensionsaspartofaresearchagendaiscriticaltoprovidingdecision-makerswiththefullestpossiblescopeofunderstanding.Furthermore,dueconsiderationofthesefactorsmayreducetheriskthatresearchisperceivedasasteptowardsinevitabledeploymentofSRM.SocietaldimensionsincludesocioeconomicbenefitsandrisksofSRMrelativetothoseofclimatechangeitself.Examplesofsocietaldimensionsincludeenvironmentaljustice,effectsongeopoliticalstability,implicationsforotheraspectsofclimatepolicy(e.g.,mitigationandadaptation),toleranceofriskswhichmaynotbewellcharacterized,issuesofpublicperceptionandacceptance,andmore.Scientificdimensionsincludenewandcontinuedground-based,airborne,andspace-basedobservations;improvingglobalmodelingofSRMapproachesandscenarios;theneedforlaboratoryresearchandoutdoorexperiments;theabilitytodetectglobalorregionalSRMdeployments;anddevelopmentofscenariosforSRM.

1NationalAcademiesofSciences,Engineering,andMedicine.(2021a).ReflectingSunlight:RecommendationsforSolarGeoengineeringResearchandResearchGovernance.Washington,DC:TheNationalAcademiesPress.

/10.17226/25762

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ThisResearchPlanfocusesonimprovingunderstandingofthepotentialimpactsofSRM,ratherthanontechnologiesneededfordeployment.Muchofthisresearchwouldcontributetoourabilitytounderstandbasicclimateprocessesandeffectsofhumangreenhousegasemissions,aswellasoutcomesofSRM.ThisPlandrawsfromthepublishedliteratureonSRM,researchcurrentlyunderway,andotherreportsidentifyingprioritiesforSRMresearch.ThisPlanwillrequireupdatingasknowledgegrowsinthisdynamicarea.

WhilethisResearchPlanfocusesprimarilyonwhatresearchwouldbeperformed,italsobrieflydiscussesaspectsofhowthatresearchwouldbeperformed,specificallythevalueofcoordinationofFederalresearchandinternationalcooperationinSRMresearch.

InadditiontoFederalinputfromtenagencies,theResearchPlandrawsfromtheselectengagementwithstakeholdergroupsandthepublic,includinginputscollectedthroughaRequestforComment.2

Importantly,theissuanceofthisreportdoesnotsignalanyExecutiveBranchpolicydecision(s)regardingSRM.ThereportisonlyaresponsetoCongressionaldirective.AnyfuturedecisionsaroundFederalSRMactivities,includingSRMresearch,mustbeconsideredinthebroadercontextofscientificandsocietalfactors,Administrationpriorities,andavailableresources.

SuggestedCitation

OSTP.(2023).CongressionallyMandatedResearchPlanandanInitialResearchGovernanceFrameworkRelatedtoSolarRadiationModification.OfficeofScienceandTechnologyPolicy,Washington,DC,USA.

AbouttheOfficeofScienceandTechnologyPolicy

TheOfficeofScienceandTechnologyPolicy(OSTP)wasestablishedbytheNationalScienceandTechnologyPolicy,Organization,andPrioritiesActof1976toprovidethePresidentandotherswithintheExecutiveOfficeofthePresidentwithadviceonthescientific,engineering,andtechnologicalaspectsoftheeconomy,nationalsecurity,homelandsecurity,health,foreignrelations,theenvironment,andthetechnologicalrecoveryanduseofresources,amongothertopics.OSTPleadsinteragencyscienceandtechnologypolicycoordinationefforts,assiststheOfficeofManagementandBudgetwithanannualreviewandanalysisoffederalresearchanddevelopmentinbudgets,andservesasasourceofscientificandtechnologicalanalysisandjudgmentforthePresidentwithrespecttomajorpolicies,plans,andprogramsofthefederalgovernment.Moreinformationisavailableat

/ostp

.

2WhiteHouseOfficeofScienceandTechnologyPolicy.(3March2023).RequestforInputtoaFive-YearPlanforResearchonClimateIntervention.

/ostp/legal/

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ExecutiveSummary

Aprogramofresearchintothescientificandsocietalimplicationsofsolarradiationmodification(SRM)wouldenablebetter-informeddecisionsaboutthepotentialrisksandbenefitsofSRMasacomponentofclimatepolicy,alongsidethefoundationalelementsofgreenhousegasemissionsmitigationandadaptation.SucharesearchprogramwouldalsohelptopreparetheUnitedStatesforpossibledeploymentofSRMbyotherpublicorprivateactors.Aresearchprogramcharacterizedbytransparencyandinternationalcooperationwouldcontributetoabroaderbasisoftrustaroundthisissue.

Thepotentialrisksandbenefitstohumanhealthandwell-beingassociatedwithscenariosinvolvingtheuseofSRMneedtobeconsideredrelativetotherisksandbenefitsassociatedwithplausibletrajectoriesofongoingclimatechangenotinvolvingSRM.This“riskvs.risk”framing,alongwithcultural,moral,andethicalconsiderations,wouldcontributetothenecessarycontextinwhichpolicymakerscanconsiderthepotentialsuitabilityofSRMasacomponentof

climatepolicy.

Bytheirfundamentalnature,thecurrentsuiteofpotentialSRMmethodswouldnotsimplynegate(explicitlyoffset)allcurrentorfutureimpactsofclimatechangeinducedbyincreasedatmosphericgreenhousegasconcentrations.Theywouldintroduceanadditionalchange(analterationofsolarenergyatscalesdeterminedbytheparticularSRMmethod)totheexisting,complexclimatesystem,withramificationswhicharenotnowwellunderstood.

AresearchprogramaimedatimprovingquantificationoftheeffectsofpotentialSRM

methodsimplementationontheEarthsystemwouldinvolveobservations,

experimentation,andmodeling.

Researchwouldbeintendedtoaddressknowledgegapsandbuildunderstandingtoaiddecision-makingandpolicymaking.Becausesuchdecisionswouldinvolveimportantsocietaldimensions,

anyresearchprogramshouldencompassthesocietalaswellasthescientificdimensionsofSRM,includingcross-disciplinaryresearch.Effortsinthisareaalsowouldhelptofosteradvancesinunderstandingofthehumanconsequencesofclimatechange,independentofSRM.

AnyprogramofresearchintoSRMwouldbecharacterizedbytransparency,oversight,safety,publicconsultation,internationalcooperation,andperiodicreview,asoutlinedinaresearchgovernanceframework.

PhysicalAspectsofSolarRadiationModification

Observationsfrominstrumentsonground-based,airborne,andspaceborneinstrumentssupportunderstandingofthephysicalprocessesandoutcomesassociatedwithSRM.Theseincludeobservationsrelatedtoatmosphericcomposition(gasesandaerosols),aerosol–cloudinteractions,chemistry,dynamics,radiation,short-termandlong-termtrends,andseasonalvariability.

Observationsfromspaceborneplatforms(satellites)haveauniqueroleinprovidingcontinuousglobalobservationsofthebackgroundandperturbedatmosphere.Maintainingkeysatellite

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measurementsisimportantforSRMresearchaswellasforourbroaderunderstandingofEarthsystemprocesses.

KeyresearchobjectivesforimprovingglobalmodelingofSRMscenarioswouldinclude:

increasethenumberanddiversityofmodelsthatcanconductrealisticSRMsimulations;includearangeofmodeltypesfromprocess-resolvingmodelstoglobalclimatemodels;assesstheclimateresponsetoSRMacrossmultipleglobalclimatemodels,scenarios,andstrategies;performsensitivitystudiestoassessthesurfacecoolingeffectivenessofvariousSRMstrategies;useglobalmodelstostudyhowSRMwouldaffectaspectsofclimatethatdrivesocietalimpacts;andassesstherisksassociatedwithsuddenterminationofSRM.

OutdoorexperimentswouldbevaluableincombinationwithmodelandlaboratorystudiesforunderstandingtheprocessesinvolvedwithpotentialSRMdeployment.Outdoorexperimentswouldbenefitfromdevelopmentandtestingofaerosolinjectiontechnologies,observingsystems,andanalysistools.

TheabilitytodetectanyglobalorregionalSRMdeploymentswouldbeofvaluefordecision-making.Verifyingadeployment—whethercarriedoutcovertlyoropenly—overtheshort-andlong-termwouldoccurbymeasuringandmonitoringthecharacteristicsofthedeployment,whileassessingtheintendedandunintendedphysical,environmental,andsocietaloutcomes.

AninternationalscientificassessmentofthestateofunderstandingofSRMmethodswouldbevaluableinestablishingacommonunderstandingandframeofreferenceforwhatisknownandnotknownregardingthistopic.Thescopeofanassessment,ifintendedtobeofvaluetodecision-makers,shouldincludeinternationalandprivatelyfundedresearch,aswellasanyoutdoorexperimentsconductedtodate.

DevelopmentofScenariosforSolarRadiationModification

DevelopmentofastandardsetofSRMscenarioswouldbeanimportantintegratingaspectofacomprehensiveresearchprogram.Asetofscenariosshouldincludethosecarefullydesignedtoproducespecificclimateoutcomes(e.g.,“peak-shaving”orcoolingtheArcticand/orotherregions),aswellasthosethatmightbeimplementedwithouthavingbeencarefullydesigned.SRMscenariodevelopmentisaniterativeprocesswherescenariosareperiodicallyrevisedbasedonupdatedpolicychoices,newobservations,andimprovedprocess-basedunderstanding.

SinceSRMisintendedtoreducerisksassociatedwithclimatechange,aresearchprogram

wouldmostusefullyassessrisksandbenefitsassociatedwithSRMscenariosincomparison

torisksassociatedwithplausibleclimatechangescenariosnotinvolvingSRM.

SocioeconomicandEcologicalOutcomes

DecisionsconcerningwhetherandhowtodeploySRMshouldbebaseduponanunderstandingoftherisksandbenefitstohumanhealthandwell-beingofitsimplementationrelativetothoseanticipatedunderthecurrentclimatechangetrajectory.

Ofparticularimportanceisconsiderationofpotentialjeopardytodiversecommunitiesandintergenerationalequity.

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Cultural,moral,andethicalconsiderationsareoftenoverlookedinmodel-basedevaluationsandmaybeequally,ifnotmore,importanttodifferentcommunities.Inadditiontophysicalscientistsandengineers,philosophersandsocialscientistsareneededtohelpanswerquestionsrelatedtothehumandimensionsofclimatechangeandeffortstomanagethatchangethroughSRM.

ThereisapotentialforadverseoutcomestoecosystemsandtheservicestheyprovidewiththeimplementationofSRM,butthenatureandintensityoftheseoutcomes—incomparisontothoseinscenarioswithoutSRM—remainunclear,particularlyoverthelongtimeperiodsanticipatedinmanyscenarios.FurtherassessmentofoutcomestoecosystemsinSRMscenariosrelativetothoseinscenarioswithoutSRMisneeded.

Climatechangeraisesgeopoliticalrisks.SRMdeploymentcouldalsocarrysignificantgeopoliticalrisks.ResearchintothegeopoliticalramificationsofSRMwouldbeaimedatreducingthelikelihoodand/orseverityoftheserisks.

InternationalCooperationonSolarRadiationModificationResearch

IfFederalscienceagenciesweretosupportalarge-scaleprogramofSRMresearch,theycouldconsiderengaginginappropriateinternationalcooperation.Internationalcooperationcouldpromoteknowledgegains,acommoninternationalunderstandingofresearchneedsandresults,resourcesavings,socializingbestpractices(suchasactingwithfulltransparency),andreducingtheprospectofirresponsibleexperimentationand/ordeployment.

CooperationcouldinvolveoneormoreareasofSRM-relatedresearchandcouldtake

variousforms,rangingfrommodest(e.g.,anexchangeofexperts)toextensive(e.g.,aninternationalconsortium).

Potentialcooperationpartnerscouldbeengagedbasedonanynumberofcriteriaorperceivedbenefits,includingcountrieswithexpertise,availablefunding,orcapacityinaparticulararea,countrieswithlimitedopportunitiesorcapacityinacertainarea,andcountrieswithaccesstoparticularecosystems(e.g.,theoceanortheArctic).

ResearchCoordination

Anylarge-scale,multi-agencyFederalresearchprogramintoSRMshouldbecoordinatedbytheU.S.GlobalChangeResearchProgram.ThiscoordinationroleiscurrentlymandatedbytheGlobalChangeResearchActof1990andwouldapplytoallFederallyfundedresearchintoSRM,whetherperformeddomesticallyorinternationally,andwhetherinvolvingnaturalor

socialscience.OngoingresearchintoSRMinvolvingtheNationalOceanicandAtmospheric

Administration(NOAA),theNationalAeronauticsandSpaceAdministration(NASA),andtheDepartmentofEnergy(DOE)hasbeencoordinatedbytheparticipatingagencies.

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I.InitialResearchGovernanceFramework

AsoutlinedinthejointexplanatorystatementaccompanyingDivisionBoftheConsolidatedAppropriationsActforFiscalYear2022,Congressrequestedthataninteragencyworkinggroup“shouldestablisharesearchgovernanceframeworktoprovideguidanceontransparency,engagement,andriskmanagementforpubliclyfundedworkinsolargeoengineeringresearch.”ThisdocumentdescribesaninitialapproachtheExecutiveBranchcouldtaketoestablishthatframework:Furtherdevelopmentandevolutionofrelatedpoliciesmaybepursued,asappropriate.

TheBiden-HarrisAdministrationstronglyaffirmsthatclimatechangeisoneofthegreatestchallengesfacingtheworld,particularlythosecountriesandcommunitiesmostvulnerabletoitsadverseeffects.Immediate,sustained,andeffectivereductionsofglobalgreenhousegasemissionsarerequiredtoslowthepaceofclimatechangeandreducetheriskofcrossingcritical

andpotentiallycatastrophicthresholdsintheglobalclimatesystem.Thesereductionsmustoccur

whilerobustadaptationisacceleratedandwhilecapabilitiesineffectiveandresponsiblecarbondioxideremoval,suchasdirectaircaptureandpermanentsequestration,arepursuedvigorously.

TheAdministrationalsorecognizesthatthereisgrowinginterestandinvestmentinresearchonactionsthat,togetherwithmitigationmeasures,couldlimittemperatureincreaseandtherebyhelpaddresstherisksofclimatechange,includingpotentialtippingpointsandovershootscenarios.Forexample,academia,philanthropy,andtheprivatesectorhaveexaminedpreliminaryapplicationsofclimateinterventiontechniques,suchasstratosphericaerosolinjectionandmarinecloudbrightening(techniquescategorizedas“solarradiationmodification,”hereafterSRM),intendedtorapidlylimittemperatureincrease.Alongsidethepotentialbenefitsofsuchactions,seriousconcernshavebeenraisedaboutthepotentialoutcomesofSRM.Theseunknowns,andtheever-evolvingunderstandingofcomplexEarthsystems,provideacompellingcaseforresearchtobetterunderstandboththepotentialbenefitsandrisks.

TheStateofKnowledgeandCurrentExecutiveBranch

Action

Therisksofinactiontoreducegreenhousegasemissionsquicklyandsignificantlyandlimitwarmingto1.5°Cabovepreindustriallevelsareincreasinglyclear.Thisurgencywarrantsadditionalresearchtoevaluatetheefficacy,trade-offs,orotherrelevantconsiderationsofSRM.Insomecases,researchmayneedtobeundertakenwithguardrailsthatacknowledgerelevantconcerns,balancetherisksandneedtoaddressunknowns,andseektoavoidorminimizeundesirableoutcomesofbothsuchresearchandclimateimpacts.Thebelowfive-yearResearchPlan—mandatedbyCongress—highlightssomeofthekeyknowledgegapsandprioritytopicsforpotentialresearch.DiscussionsonSRMresearch,includingthesubmissionofthefive-yearResearchPlantoCongress,shouldnotbeinterpretedasendorsementofimplementationofSRM.

TheU.S.GovernmentisengagedinasubsetofSRMresearchactivitiesincludingmodeling,measurementsandmonitoring,andlaboratoryresearch—allofwhichoccurwithinexistingauthorizationsforFederalscienceagencies.Severalagencieshavealsoforyearsbeenconductingbackgroundresearchonfundamentalclimateprocessesthatareimportanttounderstandingclimatechange,generally,andthatresearchalsohasrelevancetoresearch

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concerningSRM(e.g.,understandingtheimpactofvolcanicforcingandnaturalanalogsystems,cloud–aerosolinteractions,etc.).Existingresearchisnotapreparatorymeasurefordeployment,andtheU.S.Governmentisnotcurrentlyengagedinoutdoortestingordeployment.

GoverningResearchResponsibly

Inadditiontowhatresearchtoconduct,theBiden-HarrisAdministrationseekstoensurethathowresearchisconductedmeetsthehighstandardsithassetinadvancingitsunprecedentedandambitiousclimateandcleanenergystrategies.AninteragencygrouphasbegunconsideringtheimportanceofensuringthesehighstandardsastheyrelatetoSRMactivitiesgoingforward.ThefollowingkeypointsdescribeaninitialapproachtheExecutiveBranchwouldtaketothatframework.

1.TheU.S.Governmentwillmodelresponsiblebehaviorthroughwellgovernedandtransparentresearchprograms,includingreporting,datasharing,and,asappropriate,regulationsorrulemaking.

2.TheU.S.Governmentwillencourageothercountriesandnon-Federalentitiestoshareresearchplansandresults,inlinewithprinciplesofopenscienceandtransparency.

3.Federalscienceagencies3commit—andencouragenon-Federalentitiestocommit—topromotingopenscientificresearchalignedwithF.A.I.R.E.R.(Findable,Accessible,Interoperable,Reproducible,Equitable,andResponsible)principlesofdataanddatause.

4.TheU.S.Governmentwillseektoensuretransparency,oversight,safety,publicandTribalconsultation,andperiodicreviewoffutureresearchgovernancestandardstoallowgovernancetoco-evolvewithresearchfindings.Newknowledgeandcapabilitiesmaypresentunforeseencircumstancesthatrequirenewguidanceand/orgovernancemechanisms.

InternationalCooperation

AselaboratedintheResearchPlanbelow,therearenumerouswaysinwhichtheUnitedStatesmightengageincooperationwithinternationalpartnersandtheglobalscientificcommunityonSRMresearch,andthesecanvaryaccordingtoscope,type,forum,andpotentialpartnersforsuchcooperation.

3TherelevantFederalscienceagenciesaretheNationalOceanicandAtmosphericAdministration(NOAA),theNationalAeronauticsandSpaceAdministration(NASA),theNationalScienceFoundation(NSF),theU.S.GeologicalSurvey(USGS),theDepartmentofEnergy,inparticulartheOfficeofScienceandtheirNationalLaboratories(DOE),andtheNationalInstitutesofHealth(NIH).

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II.ResearchPlan

Introduction

Solarradiationmodification(SRM)isapotentialcomplementtoothertoolsavailabletoaddressclimatechange:mitigationofgreenhousegasemissions,removalofcarbondioxide(CO2)fromtheatmosphere,andadaptationtoexistingandexpectedchangesinclimate.SRMoffersthepossibilityofcoolingtheplanetsignificantlyonatimescaleofafewyears.4Suchcoolingwouldtendtoreversemanyofthenegativeconsequencesofclimatechange,albeitwithramificationswhicharenowpoorlyunderstood.InterestinSRMisheightenedasgreenhousegasescontinuetoaccumulateintheatmosphereandassciencetellsusmoreabouttherisksassociatedwithexceedingglobaltemperaturetargets.5Atthesametime,deploymentofSRMwouldinevitablyinvolveitsownrisks,almostallofwhicharepoorlyunderstoodandsomeofwhichareunknown.

SciencetellsusthatSRMwouldnotsimplyundoallofthenegativeconsequencesofhumangreenhousegasemissions.SRMwouldnotamelioratemostoftheimpactsofoceanacidification,whichisprimarilydrivenbyrisingatmosphericcarbondioxidelevels,noreliminatethetendencyforfossilfuelburningtoworsenairquality.Inaddition,limitedresearchsuggeststhattheuseofSRMmightresultinenvironmentalimpacts,aswellasclimatevariabilityandextremeswhicharedistinctfromthoseinanyclimatewithoutSRM.6Finally,SRMmighthaltbutwouldnot