泛读教程4IsWeatherGettingWorse.docx

泛读教程4IsWeatherGettingWorse.docx

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泛读教程4IsWeatherGettingWorse

泛读教程4--Is-Weather-Getting-Worse

IsWeatherGettingWorse?

  Weatherseemsgettingworseandwildersince"MotherNatureisfullofsurprisesthesedays".Globalwarming,aheatedtopicoftoday,isoftentakenforgrantedtoberesponsiblefortheharshweather.However,scientists,likeKevinE.Trenberth,arecautiousinmakingtheirjudgment.PleasereadthefollowingarticleandfindoutwhatroleElNiňoandLaNiňaplay.

  Asyoureadthis,flipyoureyesovertothewindow.Theskyisclear,thewindlight,andthesunbrilliant.Ormaybenot－MotherNatureisfullofsurprisesthesedays.Thecalendarsaysit'sspring,buttherecouldjustaseasilybeawinterblizzard,asummerswelter,oranautumncoldsnapontheothersideofthatglasspane.Almostinaninstant,itseems,theweathershiftsfromoneseasontoanother.Andwhereveritswings,itseemsincreasinglylikelytobeextreme.

  ConsiderwhatMotherNatureslungourwaylastyearinMay,typicallythesecondworstmonthfortornadoes.Inlessthan24hours,morethan70hellholesofwindrampagedthroughOklahomaandKansas,killing49andcausingmorethan$1billionindamages.InJune,itwasheat,astheNortheastbeganroastingthroughweeksoftheworstdroughtsincethe1960s;256peopledied.ThisyearinJanuary,blizzardspoundedtheU.S.fromKansastotheAtlanticOcean.InApril,25inchesofsnowfellonpartsofNewEngland.

  Whyhasourweathergonewild?

It'sthequestioneveryone'sasking,butaverytoughonetoanswer.Althoughmanyscientistsstillaren'tconvincedthatithasgonewild,somehavebegunsaying－cautiously,hesitantly－thatextremeweathereventsareoccurringwithmorefrequencythanatanytimeinthiscentury,eventsconsistentwiththeprofileofawarmingworld."Globalwarmingisreal,"saysKevinE.Trenberth,headoftheClimateAnalysisSectionoftheCenterforAtmosphericResearchinBoulder,Colorado."Themeantemperaturesaregoingup.Thekeyquestionis:

Whatwillitdolocally?

Ithinkwe'regoingtostartfeelingitseffectsinthechangesonextremes."

  Thatdoesn'tmeanyoucanindictweirdweatherinyourneckofthewoodsasproof.MotherNatureknowshowtohidehertracks.Shehurlsatorrentialdownpourtodayandadroughttomorrowfollowedbygentlerainthenextweek.Tounderstandapatterninnaturalvariability,youcan'tlookintothesky;youhavegottostudydata.Andforahostofreasons,thatisn'teasy.

  Buttallyingupthedamageis.Inthelast20years,thiscountryhasbeenwhackedby$I70billionworthofweather-relateddisasters－hurricanes,droughts,floods,andtornadoes.Thirty-eightsevereweathereventsoccurredinasingledecade,between1988and1999;seveneventsoccurredin1998alone－themostforanyyearonrecord.

  Globally,insurancecompaniesarecallingita"catastrophetrend".InareportissuedlastDecember,MunichRe,theworld'slargestreinsurer,orinsurerofinsurancecompanies,notedthatthenumberofnaturaldisastershasincreasedmorethanfourfoldsincethe1950s.Earthquakes,whicharenotweather-related,causednearlyhalfthedeathsinthosecatastrophes;storms,floods,andotherweatherwoeskilledtheotherhalf.In1999,thenumberofcatastrophesworldwidehit755,surpassingtherecordof702setonlytheyearbefore.

  Initsfive-pointlistofcausesforincreaseddamageclaims,MunichReblamedpopulationgrowthfirst,climatechangefifth.Criticsmaywellseizeuponthistodiminishclaimsthattheweatherisgettingworse,buttakentogether,it'samorefrighteningpicture.Thankstoswellingpopulationsincitiesandalongcoastalareas,moreofEarth'spassengersarelivinginthewrongplaceatthewrongtime.

  Still,thestatisticsmeteorologistshavecollectedonextremeweathereventsaren'tenoughtoprovethattheweatherisgettingworse.Bytheirverydefinition,extremeeventshappeninfrequently,andnoonehasbeencollectingscientificallysounddatalongenoughtoknowhowcommontheyare.Forexample,astormthathappensonceacenturymightrequiretwomillennia'sworthofstormdatatodrawconclusions.Totopitoff,thecomputermodelsscientistsusetostudyclimatecrunchnumbersonascaleofcenturiesatatime."Ideally,you'dlikedatasetsthatgobackseveralhundredyears,"saysPhilipArkin,deputydirectoroftheInternationalResearchInstituteforClimatePredictionattheLamont-DohertyEarthObservatoryinNewYork."Buttheyjustdon'texist.TheU.S.datagoback50years.BeforeWorldWarII,it'sverydifficulttocomeupwithgoodnumbers.Wehavesomedataonheavyraineventsbefore1900,butthere'snothinguseful."

  Evenifscientistscouldfindgoodnumbers,computerresolutionisstilltoocoarsetobeabletoforecasthowsomethingassimpleaswarmingmightaffectclimateinspecificspotsontheglobe.Thesmallestamountofspaceonland,sea,ice,andairthatscientistscanstudyisaboutthesizeofVirginia.Iftheycrankuptheresolutionby50percenttofocusonanareahalfthatsize,theypayforitincomputingtime－acalculationthattook10daystoperformmightnowneedthreemonths.

  KeithDixon,aresearchmeteorologistattheNationalOceanicandAtmosphericAdministration'sGeophysicalFluidDynamicsLaboratoryinNewJersey,recallsoncehewasbeingaskedpreciselywhatglobalwarmingwouldmeanforstateskiresorts.Moresnow?

（Good.）Ormorerain?

（Bad.）"Icanunderstandwhybusinesspeopleorpoliticiansask.Ifyouwanttocutfuel,spendmoney,andmakedecisions,youneedtoknowwhyyoushouldbedoingthis."Addshiscolleague,TomKnutson:

"Icancertainlysympathizewiththem.Butwecan'tanswerit."

  Since1995,theliteraturehassuggestedthattherecouldbefewerfrosts,moreheatwaves,moredroughts,moreintenserainfalls,tropicalcyclones,andhurricanesinthe21stcenturywhenandifCO2levelsdouble.Buttheseprojectionsranklowontheconfidencescalebecausescientistscannotsaydefinitivelyifandhowtheeventsmightoccur.

  Allofwhichdoesn'tdotheaveragecitizenmuchgood.Hedoesn'tworryabout30-to-100-yearshiftsintheclimate.Whatgetshimisday-to-dayweather:

"Thisheat'skillingme.""Cropshavefailedherefiveyearsinarow.""Therehavebeenthreebadtornadoesinasmanyweeks."Weliveinasocietyuniquelyprivilegedtolearnaboutweatherevents－andtofearthem.TheCenterforMediaandPublicAffairs,awatchdoggroupbasedinWashington,D.C.,reportsthatmediacoverageofweatherdisastersmorethandoubledfrom1997to1998alone.

  Probablyasaresult,peoplearestartingtoblameharshweatheronglobalwarming.Politiciansaretoo.JerryMahlman,directoroftheGFDL,advisestheWhiteHouseonclimatechange.HerememberssittinginaconferencewithVicePresidentGore,whoasked:

"Canwesaythatstormswillbemoreextremeinthegreenhouse-enhancedearth?

"Thescientistdidn'tflinchashereplied,"No."Gore'sshouldersseemedtocrumple.

  Globally,the1990sstoodasthewarmestdecadeforwhichwehaverecords.Scientistsalreadypredictthatby2100,Earthcouldwarmupanother1.8to6.3degreesFahrenheit.Mostofusthinkheatwhenwethinkglobalwarming.Scientiststhinkice.They'reworriedaboutwhatwillhappenwhenallthatextraheathitstheiceatEarth'spoles.Adominanthypothesissaysthatthewatercyclewillspeedup:

Heatwillhastenoceanevaporation,andbecausehotaircanholdmoremoisture,itcouldallbewhiskedawaytorainmoreuponourheads.

  FiveyearsagotheIntergovernmentalPanelonClimateChange,aninternationalcollaborationof2000scientists,theorizedasmuchinawell-publicized56-pagereport.Thatsameyear,ateamofscientistsledbyTomKarl,nowdirectoroftheNationalClimaticDataCenter（NCDC）,studied80yearsofU.S.dataandconfirmedanincreaseinextremeprecipitationevents,alteredpatternsofrainanddrought,andrisingtemperaturessince1970.Butthescientistscautionedthatthestudyanalyzedonly80yearsofdata,confineditselftotheUnitedStates－whichoccupiesamere2percentoftheglobe－andfoundnothingoutoftherealmofpurechance.

  Withinmonthscameanother,strongerpieceofreal-worlddata,naileddownbyoneofthemencaughtinthatJanuarysnowstorm.Siftingthroughhistoricaldata,Trenberthhadfoundthatmore,longer,andstrongerElNiňoshaveoccurredduringthelast20yearsthanintheprevious120years.Thatwasunusual,achanceof1in2000.ElNiňo,theperiodicwarmingoftheequatorialPacificthatinducesstormsandotherclimaticevents,historicallyoccursonceeverythreetosevenyearsandlastsforuptotwoyears.ButevenasTrenberthpresentedhisfindingsataconferenceinMelbourne,Australia,thePacificwasexperiencinganodd,doubleElNiňo:

Thefirsthadlastedfrom1991to1993,aweakeronefrom1994to1995.TrenberthfloatedanidealpasttheaudienceinhisnativeNewZealandaccent:

Couldthisbeduetoglobalwarming?

  Theidea,Trenberthmodestlyrecalls,causedsomethingofastirintheaudience.Scientistsfoundthemselveswondering:

Whatwouldhappenifoneofnature'sstormmachines－notcompletelyunderstoodbutstilladheringtorhythmsasregularastheseasons－werepressedintoservicebyglobalwarming?

  ArchaeologicalevidencesuggestsElNiňohasbeenaroundforthousands,possiblymillionsofyears.Aknowninstigatorofstorms,floods,droughts,andsecondaryeffectslikefires,theElNiňo-SouthernOscillationcouldgoalongwaytowardexplainingmanyweatherextremes.Undernormalcircumstances,seasurfacetemperaturesriseinthetropicalPacific,fuelingstrongthunderstorms.Likeavastclimaticmailba