高级英语视听说上册听力原文.docx
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高级英语视听说上册听力原文.docx
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高级英语视听说上册听力原文
Unit5TheGlobalWarning
TheNorthPolehasbeenfrozenfor100,000years.Butaccordingtoscientists,thatwon'tbetruebytheendofthiscentury.Thetopoftheworldismelting.
There'sbeenadebateburningforyearsaboutthecausesofglobalwarming.Butthescientistsyou'reabouttomeetsaythedebateisover.Newevidenceshowsmaniscontributingtothewarmingoftheplanet,pumpingoutgreenhousegasesthattrapsolarheat.
MuchofthisnewevidencewascompiledbyAmericanscientistBobCorell,wholedastudycalledthe"ArcticClimateImpactAssessment."It'sanawkwardname—butconsiderthefindings:
theseasarerising,hurricaneswillbemorepowerful,likeKatrina,andpolarbearsmaybeheadedtowardextinction.
Whatdoesthemeltingarcticlooklike?
CorrespondentScottPelleywentnorthtoseewhatBobCorellcallsa"globalwarning."
Towersoficetheheightof10-storybuildingsriseonthecoastofGreenland.It'sthebiggesticesheetintheNorthernHemisphere,measuringsome700,000squaremiles.Buttemperaturesinthearcticarerisingtwiceasfastastherestoftheworld,soalotofGreenland'siceisrunningtothesea.
"Rightnowtheentireplanetisoutofbalance,"saysBobCorell,whoisamongtheworld'stopauthoritiesonclimatechange.Heled300scientistsfromeightnationsinthe"ArcticClimateImpactAssessment."
Corellbelieveshehasseenthefuture."Thisisabellwether,abarometer.Somepeoplecallitthecanaryinthemine.Thewarningthatthingsarecoming,"hesays."In10yearshereinthearctic,weseewhattherestoftheplanetwillseein25or35yearsfromnow."
Overthelastfewdecades,theNorthPolehasbeendramaticallyreducedinsizeandCorellsaystheglacierstherehavebeenrecedingforthelast50years.
Backin1987,PresidentReaganaskedCorelltolookintoclimatechange.He'sbeenatiteversince.
InIceland,heshowedglaciersthatweregrowinguntilthe1990sandarenowmelting.Infact,98percentoftheworld'smountainglaciersaremelting.
Corellsaysallthatwaterwillpushsealevelsthreefeethigherallaroundtheworldin100years.
"YouandIsithere,anotherfoot.Yourchildren,anotherfoot.Yourgrandchildren,anotherfoot.Anditwon'ttakelongforsealeveltoinundate,"saysCorell.
"Sealevelwillbeinundatingthelowlandsofvirtuallyeverycountryoftheworld,oursincluded,"Corellpredicts.
Tofindthesightsandsoundsofthearcticmelting,therearefewplacesbetterthanafjordinGreenland,withaglacierjustashortdistanceaway.
Pelleystoodonahugeblockoficethathadsplitofffromtheglacierandhaddroppedintothesea—abigiceberg.
"ThispartofGreenlandismeltingfasterthanjustaboutanyother.Togetasenseoftheenormityofwhat'shappening,considerthis:
TheicethatismeltinghereistheequivalentofalltheiceintheAlps,"Pelleyexplained,standingatoptheiceberg.
That'smorethan105millionacresofmeltedicein15years.JustfourminutesafterPelleyclearedoffthisberg,partoftheicecavedin.
gotabird's-eyeviewofhowunstabletheiceisbecomingonaflightwithglaciologistCarlBoggild.
Boggildanchored10researchstationstotheice.Buteverytimehecomestovisit,theiceandhisstationshavemoved.
Flyingovertheice,Pelleynoticedlotsoffissuresandcrevicesbreakingthroughtheice.
Askedwhatcausesthis,Boggildexplained,"Thisisactuallytheiceflow,whereyouhavesomuchtensionintheicethatitcannotsticktogether.Anditbreaksandopensacrevicewhichgoesabout150,200feetdown."
Theiceisalsomeltingonthesides,Boggildsays.
Highoverhead,Pelleyremarkedthatonecouldhearthewaterrunning.
"It'slikeasmallriver,"Boggildsaid.
Aleadingtheorysaysthoselittleriverslubricatethebottomoftheicesheet,helpingitmoveoffthebedrockandouttosea.
Andtheremaybenostoppingit.Arcticwarmingisaccelerating.It'sachainreaction.Assnowandicemelttheyrevealdarklandandwaterthatabsorbsolarheat.Thatmeltsmoresnowandice,andarounditgoes.
There'slongbeenadebateabouthowmuchofthisisearth'snaturallychangingclimateandhowmuchisman'sdoing.PaulMayewski,attheUniversityofMaine,saystheanswertothatquestionisfrozeninsideanicecorefromGreenland.
WithfundingfromtheNationalScienceFoundation,Mayewskihasled35expeditionscollectingdeepicecoresfromglaciers.Theicecaptureseverythingintheair,layingdownarecordcoveringhalfamillionyears.
"Wecangotoanysectionoftheicecore,totell,basically,whatthegreenhousegaslevelswere;wecantellwhetherornotitwasstormy,whatthetemperatureswerelike,"Mayewskiexplains.
broughtMayewskibacktoGreenland,wherehesayshisresearchhasproventhattheiceandtheatmospherehaveman'sfingerprintsalloverthem.
Mayewskisayswehaven'tseenatemperaturerisetothislevelgoingbackatleast2,000years,andarguablyseveralthousandyears.
Asforcarbondioxide(CO2)levels,Mayewskisays,"wehaven'tseenCO2levelslikethisinhundredsofthousandsofyears,ifnotmillionsofyears."
Whatdoesthattellhim?
"Itallpointstosomethingthathaschangedandsomethingthathasimpactedthesystemwhichwasn'tdoingitmorethan100yearsago.Andweknowexactlywhatitis.It'shumanactivity,"hesays.
It'sactivitylikeburningfossilfuels,releasingcarbondioxideandothergreenhousegases.TheU.S.isbyfarthelargestpolluter.Corellsaysthere'ssomuchgreenhousegasintheairalreadythatmoretemperatureriseisinevitable.
Evenifwestoppedusingeverycar,truck,andpowerplant—stoppingallgreenhousegasemissions—Mayewskisaystheplanetwouldcontinuetowarmanyway."Wouldcontinuetowarmforanother,aboutanotherdegree,"hesays.
That'senoughtomelttheArctic—andifgreenhousegasescontinuetoincrease,thetemperaturewillriseevenmore.Theicethat'smeltingalreadyischangingtheweatherbydisruptingoceancurrents.
CorellpointstofloodsintheU.S.,heatwavesinEurope;andwantedtoknowaboutthecatastrophic2005hurricaneseason.
"TheonethingIthinkwecansaywithafairlyhighdegreeofconfidenceistheseverityofthestorms,howstrongthestorms,thesecycloniceventslikehurricanesandcyclonesinthePacific,aregoingtoget—they'regonnabemoresevere.Nowonethingthatisindoubtiswhetherthere'llbemoreofthem,"Corellexplains.
"TheoceansoftheNorthernHemispherearethewarmestthey'vebeenonrecord.Whentheygetupinthattemperature,theyspinoffhurricanes.Well,ifitgoesupanotherdegree,it'sgonnaspawnthesewithmoreintensity,"Corellsays.
Thename"arctic"comesfromancientGreekmeaning"LandoftheGreatBear."
Butthewarmingclimateisthreateningthisiconofthearctic,thepolarbear.Flyingabovethesub-arcticregionofHudsonBay,CanadianscientistNickLunnishuntingpolarbearsina30-yearstudythattrackstheirhealth.It'sthejobofhisassistantEvanRichardsontotakethemdownwithatranquilizerdart.
Oncetranquilized,Lunncarefullychecksthebearwithapole,withoutgettingtooclose.
Thepolarbearisthelargestpredatoronland.Nativepeopleintheregionsayhe'llevenhunthumans,butnotonthedayPelleyjoinedLunn:
withthetranquilizer,thebearwasawakebutimmobile.
Thescientistsknewthisbearbyhistattoo.Hishistoryiswrittenchapterandverseinthe"bearbible."
"ThisistherecordbookofallthebearsthathavebeenhandledbyusorManitobaConservation,"Lunnexplains.
ThestudybeganattheWapuskNationalPark,becausethebearpopulationwasthoughttobethehealthiestintheworld.
Lunn'sannualcheckuprecordschangesinfat,dimensionsandaninventoryofweapons.Thepolarbearusesitsteethtohuntprimarilyonething—seals.That'swherearcticwarmingcomesin.
Polarbearscanonlyhuntontheice.Lunnsaystheiceisbreakingupthreeweeksearlierthanitdid30yearsgo.He'snowfindingfemalebears55poundslighter—weakermotherswithfewercubs.
Askedhowthebearpopulationhaschangedsincehestartedhisresearch,Lunnsays,"Whenwefirststarteddoingthisresearch,we'vedoneinventoriesinthemid-80s,inthemid-90s.Bothtimeswecameoutwithanestimateofapproximately1,200animalsforwhatisknownasthewesternHudsonBaypopulation.Thenumbersnowsuggestthatthepopulationhasdeclinedtobelow1,000."
Thebearsareunlikelytosurviveasaspeciesifthere'sacompletelossoficeinsummer,whichthearcticstudyprojectswillhappenbytheendofthiscentury.
Thereareskepticswhoquestionclimatechangeprojectionslikethat,sayingthey'renomorereliablethanyourlocalweatherman.ButMayewskisaysarcticprojectionsdonedecadesagoareprovingaccurate.
"Thatsaid,theskepticshavebroughtupsomevery,veryinterestingissuesoverthelastfewyears.Andthey'veforcedustothinkmoreandmoreaboutthedatathatwecollect.Wecanowetheskepticsavoteofthanksformakingourscienceaspreciseasitistoday,"saysMayewski.
OnebigsupporterofclimatescienceresearchistheBushadministration,spending$5billionayear.ButMr.Bushrefusestosignatreatyforcingcutsingreenhousegases.
TheWhiteHousealsodeclinedrequestforaninterview.Corell,whofirststudiedtheissueforPresidentReagan,believestheclimatechangefactsarein,evenifPresidentBushdoesnot.
"WhenyoulookattheAmericangovernment,whichissayingessentially,'Waitaminute.Weneedtostudythissomemore.Wecan'tflipourenergyuseovernight.It
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