世界經(jīng)濟論壇-全球未來空間理事會-凈零空間（英）-2021.9-22正式版

GlobalFutureCouncilonSpaceSpaceforNetZeroWHITEPAPERSEPTEMBER2021每日免費獲取報告1、每日微信群內(nèi)分享7+最新重磅報告；2、每日分享當(dāng)日華爾街日報、金融時報；3、每周分享經(jīng)濟學(xué)人4、行研報告均為公開版，權(quán)利歸原作者所有，起點財經(jīng)僅分發(fā)做內(nèi)部學(xué)習(xí)。掃一掃二維碼關(guān)注公號回復(fù)：研究報告加入“起點財經(jīng)”微信群。。Cover:@golubovy/GettyimagesContents34Executivesummary1Thenet-zerochallenge62Theroleofspacetechnologiesingettingtonetzero2.1Seeingearthasasystemfromspace2.2TheimportanceofmonitoringGHGemissions2.3SatellitesthatmonitorGHGemissions2.4Whatsatellitescommunicateaboutclimate2.5Gapsinunderstandingandopportunitiesformoreeffectivemitigation3EarthOperationsCentre7810131315181920ConclusionContributorsEndnotesDisclaimerThisdocumentispublishedbytheWorldEconomicForumasacontributiontoaproject,insightareaorinteraction.The?ndings,interpretationsandconclusionsexpressedhereinarearesultofacollaborativeprocessfacilitatedandendorsedbytheWorldEconomicForumbutwhoseresultsdonotnecessarilyrepresenttheviewsoftheWorldEconomicForum,northeentiretyofitsMembers,Partnersorotherstakeholders.?2021WorldEconomicForum.Allrightsreserved.Nopartofthispublicationmaybereproducedortransmittedinanyformorbyanymeans,includingphotocopyingandrecording,orbyanyinformationstorageandretrievalsystem.SpaceforNetZero2ExecutivesummarySatellitesarecriticaltomonitoringgreenhousegasemissions.Anewwayofanalysinganddisplayingallthedatainoneplaceisvitaltohelpingtheglobalcommunitydealwithclimatechange.Climatechangeisoneofthegreatestglobalchallengesfacinghumanity.Achievingnet-zerogreenhousegas(GHG)emissionshasbeenrecognizedascriticaltomitigatingsomeofclimatechange’sworstimpacts.Satellite(GOSAT),GOSAT-2,OrbitingCarbonObservatory(OCO)-2,OCO-3andSentinel-5P)measurethesegaseswiththeprecision,accuracy,resolutionandcoverageneededtotrackGHGemissionsglobally.Improvedunderstandingandresponsecanresultfromaholisticanalyticapproachthat,forexample,facilitatesintegratingspace,airborneandground-basedobservations,combiningcivilandcommercialcapabilities,andmanagingmarketsforemissiondata.Remotesensingsatelliteshaveincreasedthe?delityofpeople’sunderstandingofEarthsystemscienceandtheevolutionoftheplanet’sclimate,helpingtomeasuredifferentclimatechangeindicators.Satellitemeasurementsofairandseasurfacetemperaturesandofsealevels,aswellasotherspace-basedobservations,revealimportantconsequencesofawarming,changingworld.Hundredsoforganizationsconductresearchintorelevantclimatechangeprocesses,butanorganizationhasyettobeestablishedthatisdedicatedtothecontinualandintegrateddevelopmentofthetwocoremodelling?elds–Earthsystemsmodellingandeconomicengineeringmodelling–andtoembeddingtheirresultsinaphysicalvisualizationenvironmentthatcaninformandshapedecision-making.Thetimehascometobuildanewtypeofdecision-supportfacility:anEarthOperationsCentrethatleveragesspacedataandexpertisetoconductmultidisciplinaryscienceandengineeringresearch,andtosuccessfullymanageandcoordinatenet-zeroefforts.AkeymeasureofanthropogenicsourcesofclimatechangeistheemissionofGHGs.Ofallthelong-livedGHGsfromhumanactivities,carbondioxideandmethanehavethelargestimpactontheclimate.Satellitesarecriticaltomonitoringatmosphericconcentrationofbothgases,andnewsatellitesareplannedinthenearfuture.Whilesatellitesprovidevitaldata,gapsremaininmodelling,mitigationandcoordination.Currently,?vesatellites(GreenhouseGasesObservingBelow:@DarrylFonseka/GettyimagesSpaceforNetZero3Below:@AerialPerspectiveWorks/GettyimagesThenet-zerochallenge1AchievingabalancebetweenanthropogenicGHGemissionsproducedandremovedfromtheatmospherewouldbeacriticalmilestoneinmitigatingtheworstimpactsofclimatechange.SpaceforNetZero4TheWorldEconomicForumhascalledclimatechange“oneofthegreatestglobalchallengesthepledges–eventhemostambitiousestablishedthroughtheParisAgreement,whichmayormaynotberealized–arenotontracktoachievethis.Further,therecentlypublishedAR6providesnewestimatesregardingthechancesofcrossingtheglobalwarminglevelof1.5?Cinthenextdecades,and?ndsthat“unlessthereareimmediate,rapidandlarge-scalereductionsinGHGemissions,limitingwarmingtocloseto1.5?Coreven2?Cwillbebeyondreach[…]Thisassessmentisbasedonimprovedobservationaldatasetstoassesshistoricalwarming,aswellasprogressinscienti?cunderstandingoftheresponseoftheclimatesystemtohuman-causedgreenhousegasworldhaseverfaced”.Forthelastthreeyears,1climatethreatshaveoccupiedthetopthreespotsoftheWorldEconomicForumGlobalRisksReportasthemostlikelyrisksfacinghumanitywithinthenextdecade.TheIntergovernmentalPanelon2ClimateChange’s(IPCC)SixthAssessmentReport(AR6)in2021hasmadethesigni?cantextentofthatriskclearerthanever.3Achievingabalancebetweenanthropogenicgreenhousegas(GHG)emissionsproducedandremovedfromtheatmosphere(netzero)hasbeenrecognizedasacriticalmilestoneinmitigatingtheworstimpactsofclimatechange.Untilthatmilestoneisreached,eachyearwillseeyetmoreGHGemissions,whichwillfurtherheattheplanetandincreasethepotentialforclimateshiftswithcatastrophichumanconsequences.emissions”.Humanityis,inshort,alongwayaway5fromcontrollingtheriseinglobaltemperatureanditisnecessarytomoverapidlytowardsachievingnet-zeroglobalemissions.TheWorldEconomicForumisfosteringpathwaysforafuturezero-carboneconomythroughparticipationintheMissionPossiblePartnership,anallianceofclimateleadersfocusedondecarbonizationofhigh-emittingindustries.Throughthisandotherinitiatives,theForumaimstoimprovethestateoftheworldbyintegratingglobaleffortsthatrangefromactiononclimatechangetoToachievelong-termtemperaturegoals,alimitedglobal“GHGbudget”ofallowableTheconsensus,reinforcedbytheParisAgreement,isthatglobalwarmingneedstobelimitedtowellbelow2?C,preferablyto1.5?C,comparedtopre-industriallevels,andtoachievecarbonneutrality(net-zeroemissions)bymid-century.Thestateofglobalwarmingreportsfrom2020(byNASAGoddardInstituteforSpaceStudies,NationalOceanicandAtmosphericAdministration[NOAA],CopernicusClimateChangeService,BerkeleyEarth)showamedianincreaseof1.2?Ctoday.ThesciencehasmadeitclearnotonlythatanthropogenicsourcesofGHGsdominatetheincreasingchangesinclimate,butalsothatsomewarmingandsea-levelriseis,attransitiontosaferandcleanertransportation.6cumulativeemissionsmustberespectedtoavoidovershooting2?Canddestabilizingtheglobalclimate.TheForumrecognizesthatspacetechnologiesplayacriticalandincreasinglyvisibleroleinsupportingtheplanetarymanagementofclimatechangeandachievingandmaintainingglobalnet-zeroemissions.Thispaper,producedbytheWorldEconomicForumGlobalFutureCouncilonSpace,describesthecontributionofspace-basedobservationstothedisciplineofEarthsystemsciencesandtothemonitoringofessentialclimatevariables,anddescribessomeofthegapsinmodelling,mitigationandcoordination.ThepaperexploresthepotentialforanEarthOperationsCentretoaddressthosegapsandimproveprogresstowardsnetzero,assistingwithsystemstrade-offsatagloballevelandbecomingadecision-makingplatformforworldleaders.thispoint,inevitable.4Toachievelong-termtemperaturegoals,alimitedglobal“GHGbudget”ofallowablecumulativeemissionsmustberespectedtoavoidovershooting2?Canddestabilizingtheglobalclimate.TheIPCCconcludedin2018thatforareasonablechanceoflimitingwarmingto1.5?Cby2030,theworldmusthalveGHGemissionsandreachthenet-zerogoalbymid-century.CurrentnationalSpaceforNetZero5Below:@sergeyxsp/GettyimagesTheroleofspacetechnologiesingettingtonetzero2Morethan50%ofessentialclimatevariablesaremeasurableonlyfromspace.SpaceforNetZero6Spacesciencehasplayedafoundationalroleinunderstandingtheprocessesofglobalclimatechange.EarthsciencemissionsandremotesensingsatelliteshaveprovidedmuchofthebaselinedatathathaveallowedthemonitoringandanunderstandingoftheevolutionofEarth’sclimate.Morethan50%ofessentialclimatevariables(Table1)aremeasurableonlyfromspace.7Manysatellitesmeasuredifferentweather,8climatechangeandotherpropertiesofEarth,providingdataonGHGemissionsandinsightintotheconsequencesforallaspectsofclimate.TABLE1EssentialclimatevariablesmeasurablefromspaceDomainEssentialclimatevariablesSurfacewindspeedanddirection;precipitation;upper-airtemperature;upper-airwindspeedanddirection;watervapour;cloudproperties;Earthradiationbudget;carbondioxide,methane,andotherlong-livedGHGs;ozoneandaerosolpropertiesAtmosphericSea-surfacetemperature;sea-surfacesalinity;sealevel;seastate;seaice;oceancolourOceanicSource:GlobalClimateObservingSystem,SystematicObservationRequirementsforSatellite-BasedDataProductsforClimate2011Lakes;snowcover;glaciersandicecaps;icesheets;albedo;landcover;fractionofabsorbedphotosyntheticallyactiveradiation;leafareaindex;above-groundbiomass;?redisturbance;soilmoistureTerrestrial2.1SeeingearthasasystemfromspaceInthe1980s,aspartofitsEarthsciencespaceprogrammes,theNationalAeronauticsandSpaceAdministration(NASA)oftheUnitedStatesdevelopedanewmodelofEarthasanintegratedsystem-of-systems.Themodel,namedtheBrethertonDiagramforitsprimaryarchitect,FrancisBretherton,describedEarthasasystem,withinputsandoutputsaswellasinteractionsamongallitselements:liquidwater,ice,clouds,solarradiation,energy,biomass,GHGsandhumanactivity.Buildingonthisfoundationthroughthe1990sand2000s,anewdisciplineofscienceemerged–notjustthestudyoftheoceansoratmosphericchemistry,orofsolarradianceandre?ection,buttheintegratedstudyoftheinteractionandrelationshipbetweenalltheseelements:thedisciplineofEarthsystemscience.before2025.Thesemissionswillmeasurevariousaspectsofclimatechange:–TheSurfaceWaterOceanTopographymission,scheduledforlaunchin2022,willprovidefundamentalworldwideobservationsofchangingwaterlevels,slopesand?oodextentsinrivers,lakesand?oodplains.–NISAR(NASA-IndianSpaceResearchOrganizationSyntheticApertureRadar),formerlyDESDynI,isacollaborativeNASA-IndianSpaceResearchOrganizationradarsatellitemissionscheduledfor2022thatwill“determinethecontributionofEarth’smostvariablebiomasstotheglobalcarbonbudgetandcharacterizeecosystemdisturbanceandimpactsonbiodiversity”.9SatellitesSincethen,Earthsciencesatellitesfromspaceagenciesaroundtheworldhave,missionbymissionandyearbyyear,increasedthe?delityofourunderstandingofEarthsystemscience.Thesatelliteshaveledtotherealization,withincreasingcertainty,ofboththerisksthatincreasedGHGsintheprovideacriticalperspectivetoEarthsystemsciencethat–TheClimateAbsoluteRadianceandRefractivityObservatory(CLARREO)Path?nderMission,scheduledforlaunchtotheInternationalSpaceStation(ISS)in?scalyear2023,willhelpprepareforthefoundationalCLARREOmissionthatwillprovidevitalcalibrationofsolarradiancemeasurements,aprimaryinputintoclimatemodels.canhelpinatmosphererepresentandthenecessityforgettingtonet-zeroGHGemissionstostabilizetheclimate.understandingEarth’sintegratedsystem-of-systemsandtheconsequencesofnotgettingtonetzero.Thenext?veyearsarevitallyimportantforthefutureofEarthsystemscience.New,pioneeringmissionsareinpreparationforlaunch.AtNASA,fourimportantnewEarthsciencemissionsarisingfromthe2007EarthScienceandApplicationsfromSpace(ESAS)decadalsurveyaresettolaunch–ThePlankton,Aerosol,Cloud,oceanEcosystem(PACE)mission,setforlaunchin2024,willimproveunderstandingofhowtheoceanandatmosphereexchangecarbondioxide,includingthroughalgalblooms.10SpaceforNetZero7Beyondthese,whatcanbeexpectedfromfutureNASAEarthsciencemissions?ThecurrentEarthsciencedecadalsurvey11(ESAS2017-2027)GOSATfrom2009.JAXA’snextgenerationgreenhousegas-monitoringmission,GOSAT-GW,isscheduledfor2023.ESAlaunchedtheCopernicusSentinel-5Precursormissionin2017,carryingtheTROPOsphericMonitoringInstrument(TROPOMI).ESAisalsoplanningtheCopernicusCarbonDioxideMonitoringmission(CO2M).recommendedcontinuedsupporttotheseandotherprogrammesofrecord,anddesignated?vepriorityareasfortargetedobservations:aerosols;clouds,convectionandprecipitation;masschange;surfacebiologyandgeology;andsurfacedeformationandchange.12InMay2021,theUSWhiteHouseannouncedanewconceptforaNASAEarthSystemObservatorytoaddressthe?veareasoffocusestablishedbyESAS2017.13Beyondthesetoppriorities,ESAS2017recommendedthecreationofEarthSystemExplorer,anewlineofmissionswithinNASA’sEarthScienceDivisionconsistingofthreemissionsfocusedononeormoreofthefollowingareas:atmosphericwinds,GHGs,iceelevation,oceansurfacewinds,ozoneandtracegases,snowdepthandamount,andlandecosystems.14TheCopernicusprogrammehasalsohelpedprovidecontinuousmonitoringofsealevelssince1992withtheTopex-Poseidonsatellite,followedbytheJason/Sentinelsatelliteseries,whichsawitsmostrecentsatellitelaunchedin2020withanotherscheduledforlaunchin2025.CurrentlyunderdevelopmentinChina,theLIBRAEarthobservationsatelliteprojectexempli?eshowtheworldismovingtoglobalcoordinationinresponsetothecriticalimportanceofclimatechangescienceobservations.SatellitesprovideacriticalperspectivetoEarthsystemsciencethatcanhelpinunderstandingEarth’sintegratedsystem-of-systemsandtheconsequencesofnotgettingtonetzero.TheyarealsooneofthemostimportanttoolsfordirectlymeasuringGHGemissions.Otheragencies,suchastheJapanAerospaceExplorationAgency(JAXA)andtheEuropeanSpaceAgency(ESA),havealsobeenactiveinthe?eldofEarthsciencesatellites.JAXA’sGOSAT-2missionwaslaunchedin2018,afollow-onto2.2TheimportanceofmonitoringGHGemissionsContinuous,high-resolutionglobalmeasurementsofGHGsarecriticalforunderstandingclimatechange.GHGemissionsbeganrisingdramaticallyinthe1800sduetotheIndustrialRevolutionandchangesinlanduse.15AnthropogenicsourcesofGHGsincludecombustionoffossilfuels,deforestation,fertilizers,livestockfarmingandlandfills.AccordingtoCopernicus,theEuropeanUnion’s(EU)EarthObservationProgramme,“ofallthelong-livedgreenhousegasesemittedbyhumanactivities,theonesthathavethelargestclimateimpactarecarbondioxide(CO),2methane(CH)andnitrousoxide(NO)”.1642Satellitedata(Figure1)showthatatmosphericconcentrationsofCOandCHareincreasing24atannualaverageratesof0.6%and0.4%,respectively.SatellitescannotcurrentlymeasureN2Oasaccurately.17FIGURE1Globalcarbondioxideandmethane,2003-2019Note:ppm=partspermillion;ppb=partsperbillionSource:EuropeanSpaceAgency,ESAclimateof?ce,“ClimateChange:TheEvidencefromSpace:Satellitesprovidecruciallinesofevidenceforclimatechange”,/en/evidence/observations-change(accessed23August2021)SpaceforNetZero8CO2CarbondioxideCOisanaturallyoccurringgasimportantforlifeconstitutesbetween20and80%ofCOemissions22onEarth.Sharpincreasesordecreases,however,canin?uenceitsatmosphericbalanceandaltertheglobalclimate.TheEarthsystemmaintainsacheckandbalanceonCOthroughthecarbonfromfossilfuelandlandusechangeandis~50%onaverage.[…]MeasurementsoftheincreasinginventoryofcarboninseawaterindicatethatalmostaquarteroftheCOemittedbyhumanactivitiesis22cycle,theprocessinwhichlarge?uxesofCObeingabsorbedbytheocean,whereitcontributestooceanacidi?cation.[…]anotherquarteroftheCOemittedbyhumanactivitiesisabsorbedby2travelbetweentheatmosphere,landbiosphereandoceansthroughsourcesandsinks.ThefractionofanthropogeniccarbonreleasenotreabsorbedbytheEarthsystemhasincreasedconcentrationofatmosphericCObymorethan50%above2processesonland.”21Thearticlecontinues:“Theef?ciencyofthesenaturallandandoceansinksalsoappearstovarydramaticallyfromyeartoyear.Becausetheidentity,location,andprocessescontrollingthesenaturalsinksarenotwellconstrained,itisnotclearhowtheywillrespondinthefuture.”22Asaresult,itiscriticaltohaveaholisticviewofhowcarboncontentisincreasingintheatmosphere,howmuchisduetohumanactivitiesrelativetothenaturalcycle,andhowthecarboncyclemayamplifyormitigatefutureclimatechange.2pre-industriallevelsof280ppm.18AccordingtoNOAAmeasurements,theglobalaverageatmosphericCOconcentrationin2020was2412.5ppm,anincreaseof2.6ppmcomparedto2019.19IncreasedlevelsofanthropogenicCOare2widelybelievedtobetheprimarydriverofclimatechange.20Whileothergasessuchasmethanehavemorepotentheat-trappingabilityonamolecule-by-moleculebasis,theyarefarlessabundantandhaveashorterlifetimeintheatmosphere,sotheyhaveasmallerimpactontheclimate.Today,aninternationalnetworkofground-basedGHGmeasurementstationsintheWorldMeteorologicalOrganization’sGlobalAtmosphericWatchandtheTotalCarbonColumnObservingNetworkprovideprecisemeasurementsofatmosphericCOconcentrationfromoveraThecarboncycleiscomplex,withmanynaturalsourcesofCOincludingoceans,decomposing2biomassandventingvolcanoes.Theseareoffsetbysinkslikephotosynthesisandoceanabsorption.Carbonexchangevariesseasonally;netcarbonuptakebyplantsoccursduringspringandsummer,whileinthefallandwinter,photosynthesisdeclinesinthemiddleandupperlatitudes,andplantrespirationexceedsphotosynthesis,returningCO2totheatmosphere.2hundredlocations.Theircoverage,however,istoolimitedtoprovideacompleteglobalpicture.ObservationsfromvarioussatelliteinstrumentshavebeenanalysedtoestimatetheabundanceofatmosphericCO.Theseestimatesarenotas2accurateasthosefromtheground-basednetworkbutcomplementthosedatawithmuchgreaterspecialresolutionandcoverage.Effortsthatcombinedatafromsatellitesandtheground-basednetworkcouldprovidetheglobal,multi-variable,interlinkedsystemformonitoringGHGemissionsandattributingtheirorigins.WhileEarthcancyclethroughnaturallyoccurringCO,itcannotfullyabsorballtheadditionalcarbondioxidebuild-upgeneratedbyhumanactivitiessincetheIndustrialRevolution.AccordingtoanarticlepublishedinScience:“TheuptakeofCO2fromtheatmosphereintothelandandoceans2CH4MethaneAsnoted,methaneisamorepotentper-moleculeGHGthanCO(84timesmorepotentovera–Increasedanthropogenicemissionsprimarilyfromthefossilfuelindustry,likelyduetorapidgrowthinfrackingandderegulatedemissionsintheUnitedStatesandtocoalmininginChina25220-yearperiod),withashorteratmosphericresidencetime.Reducingmethaneemissionscanhaveagreatershort-termimpactonwarming,asworkcontinuesto?ndlonger-termsolutionstoreducingCO2.––Increasednaturalemissionsfrommeltingpermafrost,wetlandsand?oodzonesAccordingtotheInternationalEnergyAgency,a75%reductioninmethaneemissionsfromtheenergysectorwouldbepossibleifalloptionsformethaneemissionsabatementweredeployedacrosstheoilandgassectors.23(SatelliteobservationshavebeenmadeofmethanefromUSenergy-producingregions;seeFigure2.)Instead,however,anunexpectedincreaseinmethaneconcentrationshasoccurredsince2007.24Threemaininterrelatedcauseshavebeenproposed:Reducedcapacityofmethanesinks:“Changinghydroxylradical(OH)concentrationintheatmosphere,causedbyotheratmosphericpollutants,meansthatnaturalsinksmaynotbeasef?cientatbreakingdownatmosphericmethane.”26Asaresult,thenumberofsatellitesfocusedonmethanemeasurementshasriseninrecentyears,andmanyareplannedinthenearfuture.SpaceforNetZero9Public-sectorsatellites,suchasJapan’sGOSATandGOSAT-2,andtheCopernicusSentinel-5PrecursorTROMPI,arefocusingonregional-scaleglobalmeasurements.Private-sectoreffortsarefocusedonsurveying“super-emitters”,whichareresponsibleforanoutsizedshareoftotalemissions.In2017,theEnvironmentalDefenseFund(EDF)measuredmethaneemissions,comparingemissionsinventory)estimates.TheEDFfoundthat“1%ofnaturalgasproductionsitesaccountedfor44%oftotalemissionsfromallsites,or10%ofsites80%ofemissions”.27Thesesuper-emittersthereforerepresenttheeasytargetsthattheGHGobservationcommunitycaninitiallyprioritizeformonitoring.Satelliteshavethepotentialtosupportaholisticpictureofthesesuper-emitters,whicharetypicallycoalminevents,abandonednaturalgaswellsandgasdistributionnetworks.top-down(airbornemeasurementsofambientconcentrations)withbottom-up(ground-basedFIGURE2DailysatelliteobservationsofmethanefromUSoilandgasproductionregions1December2018-31March2019FromTROPOMIsensorsovertheUnitedStatesNote:ppbv=partsperbillionbyvolumeSource:deGouw,JoostA.,etal.,“DailySatelliteObservationsofMethanefromOilandGasProductionRegionsintheUnitedStates”,Scienti?cReports,vol.10,no.1379,2020,/articles/s41598-020-57678-4articles/s41598-020-57678-4(accessed21August2021)2.3SatellitesthatmonitorGHGemissionsThe?rstspace-basedsensorthatwassensitivetoCOandCHnearthesurface,wheremostsourcesandsinksarelocated,wastheESAEnvisatSCIAMACHYinstrument,whichoperatedbetween2002and2012.The?rstdedicatedspace-basedGHGsensorswereJapan’sGOSAT,launchedin2009,andNASA’sOCO-2launchedin2014.ThesesensorswerefollowedbyGOSAT-2in2018andOCO-3in2019.othergasesabsorbadistinctsetoffrequenciesorcoloursofthislight,whichprovidesan24identi?cation?ngerprintforeachgas.TheOCO-2sensormeasuresthesunlight’sintensityatthefrequenciespartiallyabsorbedbyCOand2molecularoxygen.ThisinformationisanalysedtoestimatetheconcentrationofCOandits2variationswithlocationandtime.BothhumanactivitiesandnaturalprocessescanchangeatmosphericCOconcentrationsoverTheOCO-2satellitecollectsglobal2measurementswiththeneededprecision,coverageandresolutiontohelpresolveCO2sourcesandsinksonregionaltoglobalscales.EstimatesofatmosphericCOconcentrationsthedailycycle.OCO-3addressesanimportantmeasurementgapbyexploring,forthe?rsttime,dailyvariationsinthereleaseanduptakeofCO2byhumanactivitiesinlargeurbanareasandby2derivedfromOCO-2measurementshavebeenvalidatedagainstground-basedmeasurementsandusedtoderiveestimatesofCOemissions.Assunlightpassesthroughtheatmosphereandisre?ectedbacktothesatellite,CO2andthenaturalbiosphere,inareasincludingthemajorcarbonsystemsoftropicalrainforestsofSouthAmerica,AfricaandSouth-EastAsia,providingcrucialdataforexplainingglobalvariationsinatmosphericcarbondioxidelevels.2SpaceforNetZero10China’s?rstGHGsatellite,TanSat,waslaunchedin2016toprovidespace-basedestimatesoftheCOdistributionanditsvariationonseasonaltimeandtheAmericannon-pro?tCarbonMapperaimtomonitorGHGsatresolutionshighenoughtoattributeemissionsdirectlytoindividualfacilitiesaroundtheworld.In2016,GHGSatlaunchedClaire,the?rstofasmallsatelliteconstellationdedicatedtomonitoringGHGsatresolutionsof2scales.Europe’sSentinel-5Precursor,launchedin2017,measuresseveralatmospherictracegases,includingmethane.ItwillbefollowedbySentinel-5Ain2023.ThesetwoSentinelsandthethree-satelliteCOMonitoring(CO2M)constellationin25m.GHGSathasthreesatellitesinorbitand2planstohaveaconstellationoftenby2023.CarbonMapperanditspartners–theStateofCalifornia,NASA’sJetPropulsionLaboratory,Planet,UniversityofArizona,ArizonaStateUniversity,HighTideFoundation,andRMI–aredevelopingaconstellationofsatelliteswith30-metreresolutionanddailyrevisittimes,expectedtobeoperationalby2025.22025willsupporttheEU’sCopernicusAtmosphereMonitoringService,whichestimatesnet?uxesofCO,NOandCHonEarth’ssurface,aswellThesesatelliteswillhelptodifferentiatehuman-producedemissionsof224asGHGemissionsfrombiomassburningandwild?res.Thesesatelliteswillhelptodifferentiatehuman-producedemissionsofCOfromthose2originatingfromnaturalprocesses,withthegoalofhelpingEUMemberStatesandothercountriestrackprogressinachievingtheParisAgreementandotherdecisionsregardingtheCObudget.WithCOfromthoseMethaneSAT,asubsidiaryoftheEDF,planstolaunchanEarthobservationsatellitein2022thataimsto?llagapbetweenpointsourceandglobalmappingsatellites.Itwilldetecthigh-emittingpointsourcesovera200-kmviewpathata4002originatingfrom2itshighspatialresolution(2kmby2km)andglobalcoverage,CO2Mwillallowscientiststopinpointtheexactsourceofemissions.naturalprocesses.x130mresolution,coveringalargerproportion2TheGeostationaryCarbonCycleObservatory(GeoCarb)missionisscheduledtolauncharound2024.Fromgeostationaryorbit(GEO),GeoCarbwillmonitorCO,carbonmonoxide(CO)andCH,ofemissionsbutwithlessspatialgranularitythanpoint-sourcedetectors.Thesecommercialandnon-governmentalGHGsatellites(seelist,Table2)complementthe24aswellasplanthealthandvegetationstressacrossNorth