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Unit8FocusonGlobalWarmingJohnWeierTwenty-fiveyearsagoifyoumadeatriptothelocallibraryandperusedtheperiodicalsectionforarticlesonglobalwarming,you’dprobablyhavecomeupwithonlyafewabstractsfromhardcoresciencejournalsormaybeablurbinsomeesotericgeopoliticalmagazine.AsanInternetsearchonglobalwarmingnowattests,thesubjecthasbecomeasrootedinourpublicconsciousnessasMadonna2ormicrowavecooking.1Perhapsallthisattentionisdeserved.Withthepossibleexceptionofanotherworldwar,giantasteroid,oranincurableplague,globalwarmingmaybethesinglelargestthreattoourplanet.2Fordecadeshumanfactoriesandcarshavespewedbillionsoftonsofgreenhousegasesintotheatmosphere,andtheclimatehasbeguntoshowsomesignsofwarming.Manyseethisasaharbingerofwhatistocome.3Ifwedon’tcurbourgreenhousegasemissions,thenlow-lyingnationscouldbeawashinseawater,rainanddroughtpatternsacrosstheworldcouldchange,hurricanescouldbecomemorefrequent,andElNinoscouldbecomemoreintense.OurWarmingPlanetWhathasworriedmanypeoplenowisthatoverthepast250yearshumanshavebeenartificiallyraisingtheconcentrationofgreenhousegasesintheatmosphere.Ourfactories,powerplants,andcarsburncoalandgasolineandspitoutaseeminglyendlessstreamofcarbondioxide.Weproducemillionsofpoundsofmethanebyallowingourtrashtodecomposeinlandfillsandbybreedinglargeherdsofmethane-belchingcattle.Nitrogen-basedfertilizers,whichweuseonnearlyallourcrops,releaseunnaturalamountsofnitrogenoxideintotheatmosphere.Oncethesecarbon-basedgreenhousegasesgetintotheatmosphere,theystaytherefordecadesorlonger.AccordingtotheIntergovernmentalPanelonClimateChange(IPCC)sincetheindustrialrevolution,carbondioxidelevelshaveincreased31percentandmethanelevelshaveincreased151percent.Paleoclimatereadingstakenfromfossilrecordsshowthatthesegases,twoofthemostabundantgreenhousegases,areattheirhighestlevelsinthepast420,000years.ManyscientistsfearthattheincreasedconcentrationsofgreenhousegaseshavepreventedadditionalthermalradiationfromleavingtheEarth.Inessence,thesegasesaretrappingexcessheatintheEarth’satmosphereinmuchthesamewaythatawindshieldtrapssolarenergythatentersacar.4Muchoftheavailableclimatedataappeartobackthesefears.5TemperaturedatagatheredfrommanydifferentsourcesallacrosstheglobeshowthatthesurfacetemperatureoftheEarth,whichincludestheloweratmosphereandthesurfaceoftheocean,hasrisendramaticallyoverseveraldecades.Worldwidemeasurementsofsealevelshowariseof0.1to0.2metersoverthelastcentury.That’sanincreaseofroughly1℃every4,000years.Readingsgatheredfromglaciersrevealasteadyrecessionoftheworld’scontinentalglaciers.Takentogether,allofthesedatasuggestthatoverthelastcenturytheplanethasexperiencedthelargestincreaseinsurfacetemperaturein1,000years.Notsurprisingly,manyscientistsspeculatethatsuchchangesintheclimatewillprobablyresultinhotterdaysandfewercooldays.6AccordingtotheIPCC,landsurfaceareaswillincreaseintemperatureoverthesummermonthsmuchmorethantheocean.Themid-latitudetohigh-latituderegionsintheNorthernHemisphere—areassuchastheContinentalUnitedStates,Canada,andSiberia—willlikelywarmthemost.Theseregionscouldexceedmeanglobalwarmingbyasmuchas40percent.Asfarashumanhealthisconcerned,thosehithardestwillprobablyberesidentsofpoorercountriesthatdonothavethefundstofendagainstchangesinclimate.7Aslightincreaseinheatandraininequatorialregionswouldlikelysparkanincreaseinvector-bornediseasessuchasmalaria.Moreintenserainsandhurricanescouldcausemoreseverefloodingandmoredeathsincoastalregionsandalongriverbeds.Evenamoderateriseinsealevelcouldthreatenthecoastlinesoflow-lyingislandssuchastheMaldives.Allacrosstheglobe,hottersummerscouldleadtomorecasesofheatstrokeanddeathsamongthosewhoarevulnerable,suchasolderpeoplewithheartproblems.Thewarmertemperaturesmayalsoleadtohigherlevelsofnear-surfaceozonefromcarsandfactories,whichwouldlikelycausemoreperilousairqualitydaysandhospitaladmissionsforthosewithrespiratoryproblems.TakingActionsFortunately,wecantakeactionstoslowdownglobalwarming.8Globalwarmingresultsprimarilyfromhumanactivitiesthatreleaseheat-trappinggasesandparticlesintotheair.Themostimportantcausesincludetheburningoffossilfuelssuchascoal,gas,andoil,anddeforestation.Toreducetheemissionofheat-trappinggaseslikecarbondioxide,methane,andnitrousoxides,wecancurbourconsumptionoffossilfuels,usetechnologiesthatreducetheamountofemissionswhereverpossible,andprotecttheforestsintheworld.Wecanalsodothingstomitigatetheimpactsofglobalwarmingandadapttothosemostlikelytooccur,9e.g.,throughcarefulplanningandotherstrategiesthatreduceourvulnerabilitytoglobalwarming.Butwecan’tstopthere.Wearealsoadvocatingpoliciesthatwillcombatglobalwarmingoverthelongterm,thingslikecleancarsthatrunonalternativefuels,environmentallyresponsiblerenewableenergytechnologies,andstoppingtheclear-cuttingofvaluableforests.Clearly,globalwarmingisahugeproblem.Itwilltakeeveryone—governments,industry,communitiesandindividualsworkingtogethertomakearealdifference.Fortunatelyyoucanbepartofthem.关注全球气候变暖二十五年前，如果你想去当地的图书馆通过各种期刊搜索关于全球气候变暖的文章的话，很可能你只能找到一些刊登在核心自然科学期刊或非常专业的地理科学杂志上的同类文章的摘要。然而，当今因特网搜索结果表明全球气候变暖，就像麦当娜或微波炉一样，成为所有人都十分关心的话题。应该说公众对全球气候变暖的