【5A版】全球变暖-(英文).ppt

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1、WhatisGlobalWarming?Globalwarmingistheobservedcentury-scaleriseintheaveragetemperatureofEarth'sclimatesystem.全球变暖是指全球气温在近一百年来不断上升，呈现变暖的趋势，这样一种气候变化特征。Thecauseofglobalwarming1.Naturalcause:Thegreenhouseeffect2.Humanreasons:HumanactivitiesThegreenhouseeffectThegre

2、enhouseeffectisaprocessbywhichthermalradiationfromaplanetarysurfaceisabsorbedbyatmosphericgreenhousegases,andisre-radiatedinalldirections.Sincepartofthisre-radiationisbacktowardsthesurfaceandtheloweratmosphere,itresultsinanelevationoftheaveragesurfacetemperatur

3、eabovewhatitwouldbeintheabsenceofthegases.温室效应是一个过程,从行星表面热辐射被大气吸收温室气体,并再次辐射向四面八方。因为这部分再辐射回到地表和低层大气,它导致海拔平均表面温度高于没有这部分气体。Humanactivities1.Industrialwastegases2.Deforestation3.TrafficjamIndustrialwastegasesDeforestitionTrafficjamWhat'retheeffectsofglobalwarmingNe

4、gativeeffects1.Causethesealeveltorise2.Meltingglaciers3.Droughts4.DisappearanceofspeciesPositiveeffects1.makeplantsgrowfaster2.cropswillproducemoreDroughtsIftheearth'saveragetemperature4degreesCelsius,theworldwillhavemorethan30millionpeoplewatershortages.如果地球平均

5、气温上升4摄氏度，全球就会有30多亿人面临缺水问题。Meltingglacierstheearth‘spolesislandfatesnowmeltcanleadtorisingsealevels,manyislandswillbedrowned,someislandmaynotexist.地球两极冰雪融化会导致海平面上升，众多岛屿将被淹没，一些岛国可能不复存在。So,letusdoourbesttosolvethisproblem,orwewillbearthisprobleminthefuture