Geo notes(LORMS)

1 Causesofclimatechange(naturalandhuman) Naturalcauses(ChangesintheEarth’sorbitandangleoftilt,sunspotoccurrences,large-scalevolcaniceruptions) Humancauses(Burningoffossilfuels,changinglanduse) —————————————————————————————————————————- Naturalcauses: ChangesintheEarth’sorbit:TheEarth’sorbitshiftsfromcirculartoellipticalandback.Whenmostelliptical,Earthtravelsinanovalpath,receivingmoresolarradiationatitsclosestapproachthanatitsfarthestpoint.Forexample,Earth’sorbitshiftsfromcirculartoellipticalevery100,000years,affectingseasonalsolarenergylevels. Earthtilt:TheEarth’saxistiltsbetween21.5ºand24.5º.Whentiltdecreases,hemispheresleanfurtherfromtheSun,causingwarmerwinters,coolersummers,andallowingicesheetstobuild,coolingtheEarth.Forexample,theEarth’stiltchangesevery41,000years. Sunspotoccurrences:Highersunspotactivityislinkedtoincreasedsolarradiation.Thoughsunspotsarecooler,areasaroundthememitmoreenergy,raisingEarth’stemperatures.PeriodsofmaximumsunspotsgenerallyalignwithwarmersurfacetemperaturesonEarth,followingan11-yearcycle. Large-scalevolcaniceruptions:Volcaniceruptionsreleasecarbondioxide,watervapor,sulfurdioxide,dust,andashintotheatmosphere.Sulfur-basedparticles,dust,andashspread,reflectingsolarenergybackintospace,temporarilycoolingEarth.Forexample,MountPinatubo’s1991eruptionloweredglobaltemperaturesby0.6°Cfor15months. —————————————————————————————————————————- Humancauses: Burningfossilfuels:Fossilfuels,richincarbon,releasecarbondioxideandothergreenhousegaseswhenburned,enhancingthegreenhouseeffect.Theypoweractivitieslikeagriculture,industry,andurbanization.Sincethe1880sindustrialrevolution,fossilfuelusehassurged,nowcontributingover35billiontonnesofcarbondioxideemissionsyearly. Changinglanduse Deforestation:Large-scaledeforestationforagriculture,industry,andurbanizationenhancesthegreenhouseeffect.Forestsareclearedforresources(timber)andlanduse,reducingcarbondioxideabsorptionbytrees.Cuttingorburningtreesreleasesstoredcarbon,whileexposedsoilincreasescarbondioxidethroughoxidation.Forexample,tropicaldeforestationcontributesroughly20%ofglobalgreenhousegasemissions. Agriculture:Aspopulationsgrow,forestsareclearedforagriculture,contributingabout30%ofglobalgreenhousegasemissionsannually.Keyfactorsincludeburningfossilfuelsformachinery,nitrousoxide

2 fromfertilizers,andmethanefromlivestockanddecomposition.Forexample,paddyricefieldscontribute5-20%ofglobalmethaneemissionsduetorapiddecomposition. Industries:Industriesburnfossilfuelsforenergyinmanufacturing,transport,power,andmining,causing43%ofglobalgreenhousegasemissions.Factoriesmakinggoodslikecementandsteelreleasecarbondioxidefromburningcoalandgas.Transportinggoodswithtrucks,ships,andplanesalsoaddsemissions,whilepowerplantsandminingactivitiescontributefurthercontributetoglobalwarming. Urbanisation:Incities,fossilfuelspowervehiclesandhouseholdactivitieslikeheating,cooling,andlighting.Forexample,citiesconsume78%ofglobalenergyandsignificantlycontributetogreenhousegasemissions. ==================================