高级英语视听说上册听力原文.docx

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