应对气候变化：没有一处安全的地方

Delta’sbeta:howmuchworsetocome?WhereSouthAfricagoesnext ChinesevAmericanantitrustTheethicsofprimateresearch JULY24TH–30TH2021 Nosafeplace The3°Cfuture 012 Leaders9 Nosafeplace Theextremesoffloodandfirearenotgoingaway,butadaptationcanlessentheirimpact I n1745,astheriverLiffey,havingbrokenitsbanks,clawedatthefoundationsofthehouseinwhichhesat,theyoungEdmundBurkeexperiencedastrange,perversethrill.Themanwhowouldgoontofoundmodernconservatismdrewinspira­tionfromthisexperienceinalateressayonthesublime,writingoftheunmatcheddelightthatterribledestructioncouldstir— providedthatitiswatchedfromacertaindistance. Themostterriblethingaboutthespectacularscenesofde­structionthathaveplayedoutaroundtheworldoverthepastweeksisthatthereisnosafeplacefromwhichtoobservethem.ThegroundundertheGermantownofErftstadtistornapartliketissuepaperbyfloodwaters;LyttoninBritishColumbiaisburnedfromthemapjustadayaftersettingafreakishlyhightemperaturerecord;carsfloatlikedeadfishthroughthestreets­turned­canalsintheChinesecityofZhengzhou.Alltheworldfeelsatrisk,andmostofitis. Greenhouse­gasemissionshaveproducedaplanetmorethan1°C(1.8°F)warmerthanitwasinBurke’spre­industrialdays.Itsatmosphere,stokedupandoutofjoint,isproducingheavyweatherinwaysbothpredictedandsurprising.And,withemis­sionscontinuing,itwillgetworse. Unfortunately,2021willprobablybeoneofthe21stcentury’scoolestyears.Iftemperaturesriseby3°Cabovepre­industriallevelsinthecomingdecades—astheymight evenifeveryonemanagestohonourtoday’sfirmpledges—largepartsofthetropicsriskbe­comingtoohotforoutdoorwork(seeBriefing).CoralreefsandthelivelihoodsthatdependonthemwillvanishandtheAmazonrainforestwillbecomeaghostofitself.Severeharvestfail­ureswillbecommonplace.IcesheetsinAntarc­ticaandGreenlandwillshrinkpastthepointof noreturn,promisingsearisesmeasurednotinmillimetres,astoday’sare,butinmetres. Sixyearsago,inParis,thecountriesoftheworldcommittedthemselvestoavoidingtheworstofthatnightmarebyeliminat­ingnetgreenhouse­gasemissionsquicklyenoughtoholdthetemperaturerisebelow2°C.Theirprogresstowardsthatendre­mainswoefullyinadequate.Yeteveniftheireffortsincreaseddramaticallyenoughtomeetthe2°Cgoal,itwouldnotstopfor­estsfromburningtoday;prairieswouldstilldryouttomorrow,riversbreaktheirbanksandmountainglaciersdisappear. Cuttingemissionsisthusnotenough.Theworldalsourgent­lyneedstoinvestinadaptingtothechangingclimate.Thegoodnewsisthatadaptationmakespoliticalsense.Peoplecanclearlyseetheneedforit.Whenacountryinvestsinflooddefencesitbenefitsitsowncitizensaboveallothers—thereisnofree­riderproblem,astherecouldbeforemissionsreduction.Nordoesallthemoneycomefromthepublicpurse;companiesandprivateindividualscanseetheneedforadaptationandactonit.Whentheydonotdoso,insurancecompaniescanopentheireyestotheriskstheyarerunning. Someadaptationisfairlyeasilysetinplace.SystemsforwarningGermansofcomingfloodswillsurelynowimprove(seeEuropesection).Butotherproblemsrequiremuchlargerpublic investment,likethatwhichhasbeenputintowater­manage­mentintheNetherlands.Richcountriescanaffordsuchthings.Poorcountriesandpoorpeopleneedhelp,whichiswhytheParisclimateagreementcallsforannualtransfersof$100bnfromrichtopoor. Therichcountrieshavenotyetliveduptotheirsideofthis.OnJuly20thJohnKerry,PresidentJoeBiden’sspecialenvoyonclimatechange,reiteratedAmerica’spledgetotripleitssupportto$1.5bnforadaptationinpoorercountriesby2024,partofabroadermovetoincreaseinvestmentinadaptationandmitiga­tionindevelopingcountries.Moresucheffortsarevital. Buttheyalsohavelimits.Makingdowithlesswatermaybepossible;gettingbyonnoneisnot.Somelevelsoftemperatureandhumiditymakeoutdoorsactivityimpossible.Therecomesonefloodtoomany,afterwhichyouabandontheland.Whenthereefisgone,itisgone. IftheParisgoalofkeepingtherisebelow2°Cismet,thefullextentofthoselimitswillnotbetested.Butemission­cuttingzealmaynotaccelerateasrequired.Andtheclimatesystemcouldprovemoresensitivethanithasshownitselftobetodate,assomescientistsbelievepossible,producingmorewarmingpertonneofcarbonintheatmosphere. Henceitisalsoprudenttostudythemostspectacular,andscary,formofadaptation:solargeoengineer­ing.Thisseekstomakecloudsorparticlelayersintheatmosphereabitmoremirror­like,re­flectingawaysomesunlight.Itcannotprovideastraightforwardequalandoppositeresponsetogreenhouse­gaswarming;itwilltend,forex­ample,toreduceprecipitationsomewhatmorethantemperature,potentiallychangingrainfallpatterns.Butresearchoverthepast15yearshas suggestedthatsolargeoengineeringmightsignificantlyreducesomeoftheharmsfromgreenhousewarming. Whatnobodyyetknowsishowsuchschemescouldbedevel­opedsoastoreflectnotjusttheinterestsoftheirinstigators,butalsothoseofallthecountriestheywillaffect.Differentcoun­triesmightseekdifferentamountsofcooling;somewaysofput­tingsolargeoengineeringintoeffectwouldhelpsomeregionswhileharmingothers.Noristhereyetacompellingrejoindertotheriskthattheveryideaofsuchthingstomorrowreducestheincentivetobeambitiousincuttingemissionstoday. Whengoodmendonothing Tothinkaboutsolargeoengineeringrequiresfacingthosepro­blems—andtheriskthatpowerswithlittlein