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1、版权所有：文都韩苏关注新浪微博：韩苏_suger2014考研基础阅读每日一篇（37）Unit7科学世界Text7正文Intheatmosphere,carbondioxideactsratherlikeaone-waymirror--theglassintheroofofagreenhousewhichallowsthesun’sraystoenterbutpreventstheheatfromescaping.Accordingtoaweatherexpert’sprediction,theatmospherewillbe3℃
2、warmerintheyear2050thanitistoday,ifmancontinuestoburnfuelsatthepresentrate.Ifthiswarminguptookplace,theicecapsinthepoleswouldbegintomelt,thusraisingsealevelseveralmetresandseverelyfloodingcoastalcities.Also,theincreaseinatmospherictemperaturewouldleadtogreatchangesin
3、theclimateofthenorthernhemisphere,possiblyresultinginanalterationofearth’schieffood-growingzones.Inthepast,concernaboutaman-madewarmingoftheearthhasconcentratedontheArcticbecausetheAntarcticismuchcolderandhasamuchthickericesheet.Buttheweatherexpertsarenowpayingmoreat
4、tentiontoWestAntarctic,whichmaybeaffectedbyonlyafewdegreesofwarming,inotherwords,byawarmingonthescalethatwillpossiblytakeplaceinthenextfiftyyearsfromtheburningoffuels.SatellitepicturesshowthatlargeareasofAntarcticicearealreadydisappearing.Theevidenceavailablesuggests
5、thatawarminghastakenplace.Thisfitsthetheorythatcarbondioxidewarmstheearth.However,mostofthefuelisburntinthenorthernhemisphere,wheretemperaturesseemtobefalling.Scientistsconclude,therefore,thatuptonownaturalinfluencesontheweatherhaveexceededthosecausedbyman.Thequestio
6、nis:Whichnaturalcausehasmosteffectontheweather?Onepossibilityisthevariablebehaviorofthesun.Astronomersatoneresearchstationhavestudiedthehotspotsand“cold”spots(thatis,therelativelylesshotspots)onthesun.Asthesunrotates,every27.5days,itpresentshotteror“colder”facestothe
7、earth,anddifferentaspectstodifferentpartsoftheearth.Thisseemstohaveaconsiderableeffectonthedistributionoftheearth’satmosphericpressure,andconsequentlyonwindcirculation.Thesunisalsovariableoveralongterm:itsheatoutputgoesupanddownincycles,thelatesttrendbeingdownward.Sc
8、ientistsarenowfindingmutualrelationsbetweenmodelsofsolar-weatherinteractionsandtheactualclimateovermanythousandsofyears,includingth
