THE-EARTH-IS-BECOMING-WARMER-BUT-DOES-IT-MATTER

THEEARTHISBECOMINGWARMER–BUTDOESITMATTER?Duringthe20thcenturythetemperatureoftheearthroseaboutonedegreeFahrenheit.Thatprobablydoesnotseemmuchtoyouorme,butitisarapidincreasewhencomparedtoothernaturalchanges.Sohowhasthiscomeaboutanddoesitmatter?EarthCare’sSophieArmstrongexploresthesequestions.Thereisnodoubtthattheearthisbecomewarmer(seeGraph1)andthatitishumanactivitythathascausedthisglobalwarmingratherthanarandombutnaturalphenomenon.Allscientistssubscribetotheviewthattheincreaseintheearth’stemperatureisduetotheburningoffossilfuelslikecoal,naturalgasandoiltoproduceenergy.Somebyproductsofthisprocessarecalled“greenhouse”gases,themostimportantoneofwhichiscarbondioxide.DrJaniceFosterexplains:“Thereisanaturalphenomenonthatscientistscallthe‘greenhouseeffect’.Thisiswhensmallamountsofgasesintheatmosphere,likecarbondioxide,methaneandwatervapour,trapheatfromthesunandthereforewarmtheearth,withoutthe‘greenhouseeffect’.Theearthwouldbeaboutthirty-threedegreesCelsiuscoolerthanitis.So,weaddhugequantitiesofextracarbondioxideintotheatmosphere.Itmeansthatmoreheatenergytendstobetrappedintheatmospherecausingtheglobaltemperaturetogoup.”Weknowthatthelevelsofcarbondioxidehaveincreasedgreatlyoverthelast100to150years.ItwasascientistcalledCharlesKeeling,whomadeaccuratemeasurementsoftheamountofcarbondioxideintheatmospherefrom1957to1997.Hefoundthatbetweentheseyearsthecarbondioxideintheatmospherewentupfromaround315partstoaround370partspermillion(seeGraph2).Allscientistsacceptthisdata.Theyalsoagreethatitistheburningofmoreandmorefossilfuelsthathasresultedinthisincreaseincarbondioxide.Sohowhighwillthetemperatureincreasego?DrJaniceFostersaysthatoverthenext100yearstheamountofwarmingcouldbeaslowas1to1.5degreesCelsius,butitcouldbeashighas5degrees.However,theattitudeofscientiststowardsthisriseiscompletelydifferent.Ontheonehand,DrFosterthinksthatthetrendwhichincreasesthetemperatureby5degreeswouldbeacatastrophe.Shesays,Wecan'tpredicttheclimatewellenoughtoknowwhattoexpect,butitcouldbeveryserious.Otherswhoagreewithherthinktheremaybeariseofseveralmetresinthesealevel,orpredictseverestorms,floods,droughts,famines,thespreadofdiseasesandthedisappearanceofspecies.Ontheotherhand,therearethose,likeGeorgeHambley,whoareopposedtothisview,believethatweshouldnotworryabouthighlevelsofcarbondioxideintheair.Theypredictthatanywarmingwillbemildwithfewbadenvironmentalconsequences.Infact,Hambleystates,Morecarbondioxideisactuallyapositivething.Itwillmakeplantsgrowquicker;cropswillproducemore;itwillencourageagreaterrangeofanimals-allofwhichwillmakelifeforhumanbeingsbetter.Greenhousegasescontinuetobuildupintheatmosphere.Evenifwestartreducingtheamountofcarbondioxideandothergreenhousegases,theclimateisgoingtokeeponwarmingfordecadesorcenturies.Nooneknowstheeffectsofglobalwarming.Doesthatmeanweshoulddonothing?Or,aretheriskstoogreat?