Facing the consequences.docx
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Facing the consequences.docx
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Facingtheconsequences
Facingtheconsequences
Globalactionisnotgoingtostopclimatechange.Theworldneedstolookharderathowtolivewithit
Adaptingtoclimatechange
Nov25th2010|fromPRINTEDITION
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ONNOVEMBER29threpresentativesofcountriesfromaroundtheworldwillgatherinCancún,Mexico,forthefirsthigh-levelclimatetalkssincethoseinCopenhagenlastDecember.TheorganisershopethemeetinginMexico,unliketheoneinDenmark,willbeunshowybutsolid,leadingtodecisionsaboutfinance,forestryandtechnologytransferthatwillleavetheworldbetterplacedtodosomethingaboutglobalwarming.Incrementalprogressispossible,butcontinueddeadlockislikelier.Whatisoutofreach,asatCopenhagen,isagreementonaplausibleprogrammeforkeepingclimatechangeincheck.
Theworldwarmedbyabout0.7°Cinthe20thcentury.Everyyearinthiscenturyhasbeenwarmerthanallbutoneinthelast(1998,sinceyouask).Ifcarbon-dioxidelevelsweremagicallytostabilisewheretheyarenow(almost390partspermillion,40%morethanbeforetheindustrialrevolution)theworldwouldprobablywarmbyafurtherhalfadegreeorsoastheocean,whichisslowtochangeitstemperature,caughtup.ButCO2levelscontinuetorise.Despite20yearsofclimatenegotiation,theworldisstillonanemissionstrajectorythatfitsprettyeasilyintothe“businessasusual”scenariosdrawnupbytheIntergovernmentalPanelonClimateChange(IPCC).
TheCopenhagenaccord,anon-bindingdocumentwhichwasthebestthatcouldbesalvagedfromthesummit,talksoftryingtokeeptheworldlessthan2°Cwarmerthaninpre-industrialtimes—alevelthatisratherarbitrarilyseenasthethresholdfordanger.Manycountrieshave,insigningtheaccord,promisedactionsthatwillorshouldreducecarbonemissions.IntheWorldEnergyOutlook,recentlypublishedbytheInternationalEnergyAgency,anassessmentofthesepromisesformsthebasisofa“newpoliciesscenario”forthenext25years(seechart1).AccordingtotheIEA,thescenarioputstheworldoncoursetowarmby3.5°Cby2100.Forcomparison,thedifferenceinglobalmeantemperaturebetweenthepre-industrialageandtheiceageswasabout6°C.
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TheIEAalsolookedatwhatitmighttaketohitatwo-degreetarget;theanswer,saystheagency’schiefeconomist,FatihBirol,is“toogoodtobebelieved”.EverysignatoryoftheCopenhagenaccordwouldhavetohitthetopofitsrangeofcommitments.Thatwouldprovideaworldwiderateofdecarbonisation(reductionincarbonemittedperunitofGDP)twiceaslargeinthedecadetocomeasintheonejustpast:
2.8%ayear,not1.4%.MrBirolnotesthatthehighestannualrateonrecordis2.5%,inthewakeofthefirstoilshock.
Butforthetwo-degreescenario2.8%isjustthebeginning;from2020to2035therateofdecarbonisationneedstodoubleagain,to5.5%.Thoughtheyareunwillingtosayitinpublic,thesheerimprobabilityofsuchsuccesshasledmanyclimatescientists,campaignersandpolicymakerstoconcludethat,inthewordsofBobWatson,oncetheheadoftheIPCCandnowthechiefscientistatBritain’sDepartmentforEnvironment,FoodandRuralAffairs,“Twodegreesisawishfuldream.”
Thefighttolimitglobalwarmingtoeasilytoleratedlevelsisthusover.Analystswhohavelongworkedonadaptationtoclimatechange—findingwaystolivewithscarcerwater,higherpeaktemperatures,highersealevelsandweatherpatternsatoddswiththoseunderwhichtoday’ssettledpatternsoffarmingdeveloped—arestartingtoseetheirdayintheuncomfortablyhotsun.Thatsuchmeasurescannotprotecteveryonefromallharmthatclimatechangemaybringdoesnotmeanthattheyshouldbeignored.Onthecontrary,theyaresorelyneeded.
Publicharms
Manyoftheseadaptationsarethesortsofthing—movinghouse,improvingwatersupply,sowingdifferentseeds—thatpeoplewilldoforthemselves,givenachance.Thisisonereasonwhyadaptationhasnotbeenthesubjectofpublicdebateinthesamewayasreductionsingreenhouse-gasemissionsfromindustryanddeforestationhave.Butevenifalotofadaptationwillendupbeingdoneprivately,itisalsoasuitableissueforpublicpolicy.
Forastart,someformsofadaptation
Forastart,someformsofadaptation—floodbarriers,forinstance—areclearlypublicgoods,bestsuppliedthroughcollectiveaction.Adaptationwillrequireredistribution,too.Somepeopleandcommunitiesaretoopoortoadaptontheirown;andifemissionscausedbytheconsumptionoftherichimposesadaptationcostsonthepoor,justicedemandsrecompense.
Furthermore,policymakers’neatdivisionofthetopicofclimatechangeintomitigation,impactandadaptationistoosimplistic.Somemeansofadaptationcanalsoactasmitigation;afarmingtechniquewhichhelpssoilstoremoisturebettermaywellhelpitstorecarbontoo.Someformsofadaptationwillbehardtodistinguishfromthesortofimpactyouwouldratheravoid.Massmigrationisagoodwayofadaptingifthealternativeissittingstillandstarving;topeoplewholivewherethemigrantsturnupitmaylookawfullylikeanunwelcomeimpact.
Itsfrequentlyprivateandslightlyblurrynatureisnottheonlyreasonwhyadaptationhasbeenmarginalised.Thegreenpressuregroupsandpoliticianswhohavedriventhedebateonclimatechangehaveoftenbeenlothtoseeattentionpaidtoadaptation,onthegroundthatthemorepeoplethoughtaboutit,thelessmotivatedtheywouldbetopushaheadwithemissionsreduction.Talkingaboutadaptationwasformanyyearslikefartingatthedinnertable,saysanacademicwhohasworkedonadaptationoverthepastdecade.Nowthattheworld’sappetiteforemissionsreductionhasbeenrevealedtobechronicallyweak,puttingpeopleoffdinnerislessofaproblem.
Anotherreasonfortakingadaptationseriouslyisthatitisnecessarynow.Eventssuchasthisyear’sdevastatingfloodsinPakistanmakeitobviousthattheworldhasnotadaptedtotheclimateitalreadyhas,beitman-madeornatural.Eveniftheclimatewerenotchanging,therewouldbetworeasonstoworryaboutitscapacitytodomoreharmthanbefore.Oneisthatitvariesalotnaturallyandtheperiodoverwhichtherearegoodglobalclimaterecordsisshortcomparedwiththetimescaleonwhichsomeofthatvariabilityplaysout.Peoplethusmaybeignoringtheworstthattoday’sclimatecando,letalonetomorrow’s.Theotheristhatmorelives,livelihoodsandpropertyareatrisk,evenifhazardsdonotchange,asaresultofeconomicdevelopment,populationgrowthandmigrationtocoastsandfloodplains.
Thethree-degreedifference
Inalate21st-centuryworld3°Cwarmerthanthepre-industrialnorm,whatchangesaremostmarked?
Startwiththecoldestbits.Arcticsummerseaicegoes,allowingmoreshippingandmining,removingalandscapeofwhichindigenouspeopleswereonceanintegralpart.Permafrostwarmsup,andinfrastructurebuiltonitfounders.Mostmountainglaciersshrink;somedisappear.Wintersnowsmeltmorequickly,andtherisksofspringfloodsandsummerwatershortagesontheriverstheyfeedincrease.
Sealevelrises,thoughbyhowmuchishardtosay(seechart2).Someoftherisewillbepredictable,inthatoceansexpandastheygetwarmer.Some,though,willdependonthebehaviouroftheGreenlandandWestAntarcticicecaps,whichcannotbepredictedwithanycertainty.Lessthanhalfametreby2100wouldbealuckybreak;ametre-plusispossible;morethantwoisveryunlikely,butpossiblelater.
Evenasthewatersrise,manycoastswillbesinkingbecauseofthesubsidencethatfollowsascitiessuckupgroundwater.Deltasaredoublydamned,sinceanysubsidenceisoftencoupledwithalessenedsupplyofreplenishingsediment,whichisoftentrappedupstreambyirrigation,hydropowerproductionandflood-controlprojects.Oneestimateputs8.7mmorepeopleatriskoffloodingindeltasby2050ifsealevelfollowscurrenttrends.
Tropicalcyclones,whichaccountformuchofthedamagetheseadoestotheland,maybecomelessfrequent.Buttheshareofthemostdestructive—category4andcategory5hurricanes—seemslikelytoincrease.Andbiggerstormsdodisproportionatelygreaterdamage.
Inwarmeroceans,coralbleachingtriggeredbytemperaturestresswillbemorecommon.Thisisbadforfishingandtourismbutnotnecessarilyfataltoallthereefs:
bleachedreefsmayberecolonisedbynewcorals.Reefsmayalsofacedamagefromoceanacidification,aneffectofhigherCO2levelsratherthanofwarming,asmayotherecosystems,thoughthesizeoftheimpactsisuncertain.Inwarmeroceansnutrientsindeeperwaterwillbelesseasilyrecycledtothesurface,whichmayleadtolowerbiologicalproductivityoverall.
Onland,wetplaces,suchasmuchofSouth-EastAsia,arelikelytogetwetter,anddryplaces,suchasmuchofsouthernAfricaandthesouth-westernUnitedStates,drier.Innorthernclimessomelandwillbecomemoresuitableforfarmingasspringscomesooner,whereasinthetropicsandsubtropicssomemarginallandwillbecomebarelyinhabitable.Theseplacesmaybelargesourcesofmigration.Sucheffectsarealreadyvisiblein,forexample,thelargepartofthepopulationofCôted’IvoirewhocomefromBurkinaFaso.
Increasesinaveragetemperaturewillbelessnoticeablethanthoseinextremes.Accordingtoacomparisonofover20climatemodels,by2050theprobabilityofasummerwarmerthanthewarmestyetrecordedwillbebetween10%and50%inmuchoftheworld.By2090itwillbe90%inmanyplaces(seemap).
Watchingtheweather
Peoplewillal
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