IPCC关于全球变化的最新报告(建议大家一定要看)

TwelfthSessionofWorkingGroupIApprovedSummaryforPolicymakersIPCCWGIAR5SPM-127September2013SummaryforPolicymakersDraftingAuthors:LisaAlexander(Australia),SimonAllen(Switzerland/NewZealand),NathanielL.Bindoff(Australia),François-MarieBréon(France),JohnChurch(Australia),UlrichCubasch(Germany),SeitaEmori(Japan),PiersForster(UK),PierreFriedlingstein(UK/Belgium),NathanGillett(Canada),JonathanGregory(UK),DennisHartmann(USA),EysteinJansen(Norway),BenKirtman(USA),RetoKnutti(Switzerland),KrishnaKumarKanikicharla(India),PeterLemke(Germany),JochemMarotzke(Germany),ValérieMasson-Delmotte(France),GeraldMeehl(USA),IgorMokhov(Russia),ShilongPiao(China),Gian-KasperPlattner(Switzerland),QinDahe(China),VenkatachalamRamaswamy(USA),DavidRandall(USA),MonikaRhein(Germany),MaisaRojas(Chile),ChristopherSabine(USA),DrewShindell(USA),ThomasF.Stocker(Switzerland),LynneTalley(USA),DavidVaughan(UK),Shang-PingXie(USA)DraftContributingAuthors:MylesAllen(UK),OlivierBoucher(France),DonChambers(USA),JensHesselbjergChristensen(Denmark),PhilippeCiais(France),PeterClark(USA),MatthewCollins(UK),JosefinoComiso(USA),VivianeVasconcellosdeMenezes(Australia/Brazil),RichardFeely(USA),ThierryFichefet(Belgium),ArleneFiore(USA),GregoryFlato(Canada),JanFuglestvedt(Norway),GabrieleHegerl(UK/Germany),PaulHezel(Belgium/USA),GregoryJohnson(USA),GeorgKaser(Austria/Italy),VladimirKattsov(Russia),JohnKennedy(UK),AlbertKleinTank(Netherlands),CorinneLeQuéré(UK/France),,GunnarMyhre(Norway),TimOsborn(UK),AntonyPayne(UK),JudithPerlwitz(USA/Germany),ScottPower(Australia),MichaelPrather(USA),StephenRintoul(Australia),JoeriRogelj(Switzerland),MatildeRusticucci(Argentina),MichaelSchulz(Germany),JanSedláček(Switzerland),PeterStott(UK),RowanSutton(UK),PeterThorne(USA/Norway/UK),DonaldWuebbles(USA)TwelfthSessionofWorkingGroupIApprovedSummaryforPolicymakersIPCCWGIAR5SPM-227September2013WorkingGroupIContributiontotheIPCCFifthAssessmentReportClimateChange2013:ThePhysicalScienceBasisSummaryforPolicymakersA.IntroductionTheWorkingGroupIcontributiontotheIPCC'sFifthAssessmentReport(AR5)considersnewevidenceofclimatechangebasedonmanyindependentscientificanalysesfromobservationsoftheclimatesystem,paleoclimatearchives,theoreticalstudiesofclimateprocessesandsimulationsusingclimatemodels.ItbuildsupontheWorkingGroupIcontributiontotheIPCC’sFourthAssessmentReport(AR4),andincorporatessubsequentnewfindingsofresearch.Asacomponentofthefifthassessmentcycle,theIPCCSpecialReportonManagingtheRisksofExtremeEventstoAdvanceClimateChangeAdaptation(SREX)isanimportantbasisforinformationonchangingweatherandclimateextremes.ThisSummaryforPolicymakers(SPM)followsthestructureoftheWorkingGroupIreport.Thenarrativeissupportedbyaseriesofoverarchinghighlightedconclusionswhich,takentogether,provideaconcisesummary.Mainsectionsareintroducedwithabriefparagraphinitalicswhichoutlinesthemethodologicalbasisoftheassessment.Thedegreeofcertaintyinkeyfindingsinthisassessmentisbasedontheauthorteams’evaluationsofunderlyingscientificunderstandingandisexpressedasaqualitativelevelofconfidence(fromverylowtoveryhigh)and,whenpossible,probabilisticallywithaquantifiedlikelihood(fromexceptionallyunlikelytovirtuallycertain).Confidenceinthevalidityofafindingisbasedonthetype,amount,quality,andconsistencyofevidence(e.g.,data,mechanisticunderstanding,theory,models,expertjudgment)andthedegreeofagreement1.Probabilisticestimatesofquantifiedmeasuresofuncertaintyinafindingarebasedonstatisticalanalysisofobservationsormodelresults,orboth,andexpertjudgment2.Whereappropriate,findingsarealsoformulatedasstatementsoffactwithoutusinguncertaintyqualifiers.(SeeChapter1andBoxTS.1formoredetailsaboutthespecificlanguagetheIPCCusestocommunicateuncertainty)ThebasisforsubstantiveparagraphsinthisSummaryforPolicymakerscanbefoundinthechaptersectionsoftheunderlyingreportandintheTechnicalSummary.Thesereferencesaregivenincurlybrackets.B.ObservedChangesintheClimateSystemObservationsoftheclimatesystemarebasedondirectmeasurementsandremotesensingfromsatellitesandotherplatforms.Global-scaleobservationsfromtheinstrumentalerabeganinthemid-19thcenturyfortemperatureandothervariables,withmorecomprehensiveanddiversesetsofobservationsavailablefortheperiod1950onwards.Paleoclimatereconstructionsextendsome1InthisSummaryforPolicymakers,thefollowingsummarytermsareusedtodescribetheavailableevidence:limited,medium,orrobust;andforthedegreeofagreement:low,medium,orhigh.Alevelofconfidenceisexpressedusingfivequalifiers:verylow,low,medium,high,andveryhigh,andtypesetinitalics,e.g.,mediumconfidence.Foragivenevidenceandagreementstatement,differentconfidencelevelscanbeassigned,butincreasinglevelsofevidenceanddegreesofagreementarecorrelatedwithincreasingconfidence(seeChapter1andBoxTS.1formoredetails).2InthisSummaryforPolicymakers,thefollowingtermshavebeenusedtoindicatetheassessedlikelihoodofanoutcomeoraresult:virtuallycertain99–100%probability,verylikely90–100%,likely66–100%,aboutaslikelyasnot33–66%,unlikely0–33%,veryunlikely0–10%,exceptionallyunlikely0–1%.Additionalterms(extremelylikely:95–100%,mo