Themajorreasonofglobalwarmingisduetohumanactivities,thegreenhousegasessuchascarbondioxideandnitrogenoxidesproducedbytheindustrytrapstheenergyfromthesun.Ifthereisnosuchgasintheatmosphere,theearthwillbetoocoldforanylivingorganismtosurvive,itisnaturaltohavesomegreenhousegasesintheairandsomepeoplearguethatevenwithouthumaneffectthereareevidencesshowthatthetemperatureoftheearthincreaseanddecreaseincycles,andnowwearereachinganothericeage.Oneoftheconcernsisthatthegreenhousegasesincreasedsofastthatitisnowabigthreattoallthespeciesontheearth.Thehumanactivitiesthatcauseglobalwarmingaredeforestationwhichmeansthatlesscarbondioxidecanbeconvertedbackintooxygen,useoffossilfuelswhichreleasesthecarbonsthataccumulatedformanyyearsandtheconsequencesaretherisingofsealevel,meltingoficeintheAntarcticandincreaseintemperature.Risinginsealevelmeansthatthespaceforthelandorganismdecreases.Meltingoficemeanthereleaseofanyharmfulsubstancesthatmayhavebeentrappedthousandofyearsagoandalsocauseafurtherriseinsealevel.Theincreaseintemperaturewillalsoprovideabetterconditionforbacteriaandvirustogrowwhichmeansmorediseases.