环境科学课上一部分40 listening lecture3 script40听力讲座脚本.pdfVIP

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Listentopartofalectureinanenvironmentalscienceclass.字体颜色黑色

Professor:Now,overthenextfewweeks,we’regoingtofocusoncarbonanditsroleinwhat’sknownas

thegreenhouseeffect.Everyoneknowswhatthatis,right?Butlet’smakesureanyway.Yes,Carly?

Carly:ThegreenhouseeffectiswhengasesinEarth’satmosphereactliketheglassinagreenhouseor

hothouse.TheytrapinheatwhichwarmsuptheEarth.

Professor:Gaseslike?

Carly:Watervapor,carbondioxide.

Professor:Right,carbondioxide.Wehearalotaboutcarbonthesedays,no?Carbonemissions,carbon

burning,leavingacarbonfootprint?Soit’dbeeasytoassumethatanyformofcarbonburningis

necessarilyabadthing.Butthefactisit’snotquitethatsimple.Sowe’regoingtofocustodayonthe

differencweengood,badandwell,andnot-so-bad,thepotentiallyokaycarbonburning.

Okay,goodcarbonburning.Well,webothhaveaalstakeinthisbecauseburningcarbonisthe

basisoflife.Wewouldntbehereifweourselvesweren’tburningcarbon.Basically,alllivingthingsburn

carbontosurvive.Usually,thishappensatthecellularlevel.Andwhat’sburnediscarbonintheformof

sugars,glucose.Oxygengetschemicallycombinedwithsugarsinourcellsandtheenergyproducedfrom

thatreactionisthenusedtopowerthecells.So,justbybreathingyoucansaywe’reallguiltyofcarbon

emissionandcontributetotheamountofcarbonintheatmosphere.

Anotherthingaboutatmosphericcarbon,itkeepsusfromfreezingbecausewithoutcarbonandother

greenhousegasesourplanetwouldhesametemperatureasouterspace,aroundfourdegrees

aboveabsolutezero.Andthere’snothinggoingonatthattemperature.Nopossibili