2013托福考试备考托福阅读必备背景资料(一)

经典word整理文档，仅参考，双击此处可删除页眉页脚。本资料属于网络整理，如有侵权，请联系删除，谢谢！Citieswerealreadyknowntoretainmoreheatthantheruralenvironmentsthatsurroundthem,butnewmodelingfromresearchersintheUnitedKingdomnowsuggeststhaturbanareasarealsomoresensitivetochangesinclimate.Furthermore,theywillexperiencegreaterincreasesinaveragetemperaturewithrisesinatmosphericcarbondioxide,andthecoolingeffectsofnightwillbecomemoreofamemorythanareality.Meanwhile,Washington,D.C.--whereCongressisdebatingoverwhethertopassaclimatebill--isgettingamemorablepreviewofwhatnewcomputermodelsarepredicting.Lastweek'stemperaturesbrokea100-yearrecord,andforecastersexpectthisJunewillbethehottesteverrecordedinthearea."We'regettingadramatictasteofthekindofweatherweareoncoursetobequeathtoourgrandchildren,"saidTomPeterson,chiefclimatescientistfortheNationalOceanicandAtmosphericAdministration'sNationalClimaticDataCenter.Urbanareasproducetheirownenvironments.VegetationisreplacedwithsteelandConcrete.Anaturalbreezeisreconfiguredbyskyscrapersandothertallbuildings.Soiliscoveredwithblackasphaltandloadedwithautomobiles.Eachtransformationcontributessomethingmoretowhatisknownastheurbanheatisland,orUHI,effect,aphenomenonscientistshaveknownaboutforalmost200years.Insteadofbeingconsumedbyplantsortransportedawaybysoilmoisture,muchofthedaytimeheatdirectedintourbanareasisabsorbedbyhard,impermeablesurfacesthathavenootherwayofreleasingtheirstoredheatexcepttore-radiateitatnight.Thisgivesresidentsofurbanareaslittlerelieffromthesummerheatlongafterthesunsets.InNewYorkCity,eveningairtemperaturescanbeupto14degreesFahrenheitwarmerthanthoseofruralareasthatliewithinroughly60miles,accordingtoastudypublishedbyAmericanMeteorologicalSocietyin2009.Feelingariseof5degreesby2050Thisstoredheatwillonlygetworsewithincreasedatmosphericcarbondioxide,saidMarkMcCarthy,leadauthorandaresearchscientistwiththeClimateImpactsteamattheMetOffice,theUnitedKingdom'sweatherservice.Theanalysis,publishedinGeophysicalResearchLetters,wasco-authoredwithMetOfficecolleaguesRichardBetts,headofClimateImpacts,andMartinBest.Theresearchfoundthat"urbanareasarewarmingfaster"thanruralones,inresponsetorisinglevelsofcarbondioxide,saidMcCarthy.Theirmodelspredictthaturbandaytimetemperatureswillrisebymorethan5degreesFahrenheitinmostpartsoftheworldwhencarbondioxidelevelsintheatmospherereach645partspermillion,afigurepossibleasearlyas2050.Nighttimetemperatureswillalsorisebysimilarnumbers.However,intheMiddleEast,wheretheUHIeffectisthemostextreme,citiesthroughouttheregioncouldfeelanadditional5degreesatnight.BesidestheMiddleEast,someoftheregionswhoselocalclimateismostsensitivetourbanization,includingcentralAsiaandwesternAfrica,arealsoexpectedtodoubleoreventripleinpopulationby2050,accordingtoU.N.estimates.Bythattime,morethan68percentoftheworld'spopulationwillresidewithinurbanareas--upfrom50percentin2009.Thesetrendsintemperatureandpopulationmigration,McCarthysaid,aresuretohavesignificantconsequencesforhumanhealthbyraisingthepossibilityofheat-relatedfatalities.AccordingtotheU.S.GlobalChangeResearchProgram,wintercoldsnapsraisedeathratesby1.6percent,whileheatwavesarefarmorelethal,pushingdeathratesupby5.7percent.Amongthehealthrisksassociatedwithheatwavesareheatexhaustionandheatstroke.Symptomscanincludevomiting,diarrheaandfatigue.Themostvulnerableincludeinfantsandchildren,pregnantwomenandelderlypeoplewithchronicmedicalconditions.Outdoorworkersandpeoplelivinginpovertyarealsoatrisk.Inmodelingthepropertiesofurbanenvironments,theClimateImpactsgroupalsofoundthatthenumberofhotnightsinmostcities,worldwide,isexpectedtorisesignificantly.ComplexenvironmentsthatarehardtomodelInaworldwithcarbondioxideconcentrationsof645ppm,citiessuchasLosAngeles;Tehran,Iran;andDelhi,India,willexperienceaboutthreetimesasmanyhotnightsthaninonewithhalfasmuchcarbondioxide.Despitetheseriousnessofthesepredictions,previousstudieshavechosennottoincorporateurbanenvironmentsforavarietyofreasons,McCarthysaid.Onereasonisthaturbanheatislandresearchhaslargelygrownupamongaseparatecampofclimatologistsfromthosewhodesignedtheearliestclimatemodels.Therehavealsobeenexclusionsbecauseoftheresolutionlimitsofthemostmodelingtechniques.Anotherreason,andpossiblythesimplest,isthatcitiesareextremelycomplexenvironments,anditisdifficulttoknowhowtoincorporatethemintoanymodel."Citiesaretheultimatelandscapemodelingchallenge,"saidStuartGaffin,anassociateresearchscientistwithColumbiaUniversity'sCenterforClimateSystemsResearch.Itisdifficulttoknowwheretoevenbeginstudyingtheurbanenvironment.Howdoesoneevaluatetheamountofwindagroupoftallbuildingscanchannelorhowmuchheattheyretainagainsttheconsiderableshadetheycanprovide?Howmuchheatistransferredtopavementandbuildingsbythepresenceofhumanbeings?Therearestillmanymorequestionsthanthereareanswersinthisfield,whichcontinuestomakeurbanareasamajorstumblingblockforclimatemodelers.Gaffin,whohasstudiedclimatechangesincethemid-1980sandUHIsforthelastsevenyears,saidhewas"thrilled"toseescientistslookingtointegrateurbanenvironmentsintoclimatemodels.InGaffin'sopinion,"fightingurbanheatislandsisaproxyforfightingglobalclimatechange."Aco-authoronthe2009AmericanMeteorologicalSocietytemperaturestudyofNewYorkCity,GaffinhasworkedwithMayorMichaelBloomberg'sadministrationtodevelopUHImitigationprojectstoreducethecity'sheatstress.Onesuchprojectiscalledthe"NYCCoolRoofs"program,aninitiativetoreduceelectricityuse--andthusgreenhousegasemissions--bycoatingrooftopswithreflective,whitepaint,whichcanreduceindoortemperaturesby10to20degrees,accordingtothemayor.But,Gaffinsaid,NewYorkisnotaloneinthiseffort,asmanycitiesaroundtheworldarestartingtohandlewhathecalledtheir"sunlightmanagement.""Everydegreeishuge,inacity,"Gaffinsaid."It'sthedifferencebetweenablackoutandgettingthroughaheatwave."Andablackoutcanspelllifeordeat