global-warming-全球变暖英文演讲-大学英语演讲

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张莉ZhangLi2012011678contentWecandoEffectDefinitionCauseDefinitionwhatisglobalwarming?GlobalwarmingistheobservedandprojectedincreasesintheaveragetemperatureofEarth'satmosphereandoceans.presentsituationTheEarth'saveragetemperatureroseabout0.6°Celsius(1.1°Fahrenheit)inthe20thcenturypredictionAccordingtodifferentassumptionaboutthefuturebehaviourofmankind,aprojectionofcurrenttrendsasrepresentedbyanumberofdifferentscenariosgivestemperatureincreasesofabout3°to5°C(5°to9°Fahrenheit)bytheyear2100orsoonafterwards.GlobalWarmingCauses:ATop5ListCarbondioxideemissionsfromfossilfuelburningpowerplantsCarbondioxideemissionsfromburninggasolinefortransportationDeforestation,especiallytropicalforestsforwoodpulp,andfarmlandIncreaseinusageofchemicalfertilizersoncroplandsMethaneemissionsfromanimals,agriculturesuchasricepaddies,andfromArcticseabedsCarbondioxideemissionsfromfossilfuelburningpowerplantsEveryday,moreelectricgadgetsfloodthemarket,andwithoutwidespreadalternativeenergysources,wearehighlydependentonburningcoalforourpersonalandcommercialelectricalsupply.CarbondioxideemissionsfromburninggasolinefortransportationWithourpopulationgrowingatanalarmingrate,thedemandformorecarsandconsumergoodsmeansthatweareincreasingtheuseoffossilfuelsfortransportationandmanufacturing.Ourconsumptionisoutpacingourdiscoveriesofwaystomitigatetheeffects.Methaneemissionsfromanimals,agriculturesuchasricepaddies,andfromArcticseabedsMethaneisanotherextremelypotentgreenhousegas,rankingrightbehindCO2.Whenorganicmatterisbrokendownbybacteriaunderoxygen-starvedconditionsasinricepaddies,methaneisproduced.Deforestation,especiallytropicalforestsforwood,pulp,andfarmlandTheuseofforestsforfuelisonecauseofdeforestation.Forestsremoveandstorecarbondioxidefromtheatmosphere,andthisdeforestationreleaseslargeamountsofcarbon,aswellasreducingtheamountofcarboncaptureontheplanet.IncreaseinusageofchemicalfertilizersoncroplandsInthelasthalfofthe20thcentury,theuseofchemicalfertilzershasrisendramatically.Thehighrateofapplicationofnitrogen-richfertilizershaseffectsontheheatstorageofcroplandandtherun-offofexcessfertilizerscreates'dead-zones'inouroceans.RiseinsealevelsworldwideMorekillerstormsMassivecropfailuresWidespreadextinctionofspeciesDisappearanceofcoralreefsGlobalWarmingEffects:ATop5ListinsealevelsworldwideScientistspredictanincreaseinsealevelsworldwideduetothemeltingoftwomassiveicesheetsinAntarcticaandGreenland,especiallyontheEastcoastoftheUS.However,manynationsaroundtheworldwillexperiencetheeffectsofrisingsea,whichcoulddisplacemillionsofpeople.MorekillerstormsThemaximumwindspeedsofthestrongesttropicalcycloneshaveincreasedsignificantlysince1981,accordingtoresearchpublishedinNaturethisweek.Andtheupwardtrend,thoughttobedrivenbyrisingoceantemperatures,isunlikelytostopatanytimesoon.Massivecropfailures“Climatechangeisexpectedtohavethemostsevereimpactonwatersupplies”.“Shortagesinfuturearelikelytothreatenfoodproduction,reducesanitation,hindereconomicdevelopmentanddamageecosystems.Itcausesmoreviolentswingsbetweenfloodsanddroughts.”WidespreadextinctionofspeciesAccordingtoresearchpublishedinNature,by2050,risingtemperaturescouldleadtotheextinctionofmorethanamillionspecies.Andbecausewecan'texistwithoutadiversepopulationofspeciesonEarth,thisisscarynewsforhumans.DisappearanceofcoralreefsAreportoncoralreefsfromWWFsaysthatinaworstcasescenario,coralpopulationswillcollapseby2100duetoincreasedtemperaturesandoceanacidification.The'bleaching'ofcoralsfromsmallbutprolongedrisesinseatemperatureisaseveredangerforoceanecosystems,andmanyotherspeciesintheoceansrelyoncoralreefsfortheirsurvival.BuyminimallypackagedgoodsUserecycledpaperUnplugunusedelectronicsUsepublictransportationUsecompactfluorescentbulbsChoosevegetarianorveganmealsUserecycledpaperMakethemostofscrappaperforshoppinglists,notes,scrapbooks,telephone,messages,takingnotesinclass,etc.Recycleyourpaperonlywhenithasbeenthoroughlyusedup!BuyminimallypackagedgoodsLesspackagingcouldreduceyourgarbagesignificantly,saving1,200poundsofcarbondioxideand$1,000peryear.ReducedpackagingisnotonlyagoodideabutalsoveryachievableUnplugunusedelectronicsSaveover1,000lbsofcarbondioxideandUS$256peryearbyunpluggingthemorswitchingthemoffatthewallusingapowersurge-protectorGetintothehabitofswitchingthepoweroffbeforeyougotobed.UsepublictransportationTakingthebus,thetrain,thesubwayorotherformsofpublictransportationlessenstheloadontheroadsandreducesone'sindividualgreenhousegasemissionsbyanaverageof1600poundsperyear.Choosevegetarian/veganmealsChoosingvegetarianfoodsdrasticallyreducesagriculturalwaterconsumptionandlanduse,andfavorablyimpactsbiodiversity.Vegetariandietshavebeenshowntopromotegoodhealth.张莉ZhangLi2012011678

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