11/1/16 1 #28 Climate Change II - Causes + Examples in Earth History Artist’s depiction of Earth during Hadean Eon (~4 billion years ago) Effect of Greenhouse Gases on Climate - Geologic Examples Geologic examples generally involve several factors, notes emphasize most important controls only. 1) Early Earth (4.6 - 3 billion years ago / b.y.a. or so, early Precambrian) was hothouse climate Effect of Greenhouse Gases on Climate - Geologic Examples 1) Early Earth (4.6 - 3 b.y.a. or so, hothouse ) Early Earth’s atmosphere had following characterisGcs: Early Earth Current Earth Atmospheric CO 2 abundance 98% 0.04% Atmospheric Pressure 60 1 Temperature average 290°C 16°C Why was early Earth so hot? ~200,000 Gmes more CO 2 Why so much CO 2 in atmosphere? Volcanic erupGons MUCH more common What happened to most of the CO 2 in early Earth’s atmosphere? Most of current Earth’s carbon in limestone (need liquid water to form) Effect of Greenhouse Gases on Climate - Geologic Examples 1) Early Earth (4.6 - 3 b.y.a. or so, hothouse ) High CO 2 levels in early Earth’s atmosphere due to MUCH more frequent volcanic erupGons Artist’s depiction of Earth during Hadean Eon (~4 billion years ago) Effect of Greenhouse Gases on Climate - Geologic Examples 1) Early Earth (4.6 - 3 b.y.a. or so, hothouse ) Today most carbon on Earth is in rock (limestone) Effect of Greenhouse Gases on Climate - Geologic Examples 2) End of Mesozoic/beginning of Cenozoic (100 - 50 m.y.a . ) was hothouse climate, resulted in flooding of much land on conGnents (glaciers melt, sea level rises)

28-ClimateChange-Control-II - classes.geology.illinois.educlasses.geology.illinois.edu/16FallClass/geo118/Lectures/28a... · Artist’s depiction of Earth during Hadean Eon (~4 billion

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Page 1: 28-ClimateChange-Control-II - classes.geology.illinois.educlasses.geology.illinois.edu/16FallClass/geo118/Lectures/28a... · Artist’s depiction of Earth during Hadean Eon (~4 billion

11/1/16

#28ClimateChangeII-Causes+ExamplesinEarthHistory

Artist’s depiction of Earth during Hadean Eon (~4 billion years ago)

EffectofGreenhouseGasesonClimate-GeologicExamplesGeologicexamplesgenerallyinvolveseveralfactors,notesemphasizemostimportantcontrolsonly.

1)EarlyEarth(4.6-3billionyearsago/b.y.a.orso,earlyPrecambrian)washothouseclimate

EffectofGreenhouseGasesonClimate-GeologicExamples1)EarlyEarth(4.6-3b.y.a.orso,hothouse)EarlyEarth’satmospherehadfollowingcharacterisGcs:

EarlyEarth CurrentEarth

AtmosphericCO2abundance 98% 0.04%

AtmosphericPressure 60 1

Temperatureaverage 290°C 16°C

WhywasearlyEarthsohot? ~200,000GmesmoreCO2

WhysomuchCO2inatmosphere? VolcanicerupGonsMUCHmorecommon

WhathappenedtomostoftheCO2inearlyEarth’satmosphere?

MostofcurrentEarth’scarboninlimestone(needliquidwatertoform)

EffectofGreenhouseGasesonClimate-GeologicExamples1)EarlyEarth(4.6-3b.y.a.orso,hothouse)HighCO2levelsinearlyEarth’satmosphereduetoMUCHmorefrequentvolcanicerupGons

Artist’s depiction of Earth during Hadean Eon (~4 billion years ago)

EffectofGreenhouseGasesonClimate-GeologicExamples1)EarlyEarth(4.6-3b.y.a.orso,hothouse)

TodaymostcarbononEarthisinrock(limestone)

EffectofGreenhouseGasesonClimate-GeologicExamples2)EndofMesozoic/beginningofCenozoic(100-50m.y.a.)washothouseclimate,resultedinfloodingofmuchlandonconGnents(glaciersmelt,sealevelrises)

Page 2: 28-ClimateChange-Control-II - classes.geology.illinois.educlasses.geology.illinois.edu/16FallClass/geo118/Lectures/28a... · Artist’s depiction of Earth during Hadean Eon (~4 billion

11/1/16

EffectofGreenhouseGasesonClimate-GeologicExamples2)EndofMesozoic/beginningofCenozoic(100-50m.y.a.)hothouseMajorreasonforwarmclimateishighlevelsofatmosphericCO2(7-10xtoday'slevel)from↑volcanismbyrapidseafloorspreadingassociatedwithopeningofAtlanGcOcean

EffectofGreenhouseGasesonClimate-GeologicExamples3)CenozoicCooling(50-2m.y.a.)-aberhothouseclimate,Earthcooledprogressively

Majorfactorduetoplatetectonics;Beginning~45m.y.a.,IndiabegantocollidewithEurasia,resulGnginenormousmountainrange(Himalayas)

EffectofGreenhouseGasesonClimate-GeologicExamples3)CenozoicCooling(50-2m.y.a.)-CreaGonofenormousmountainrangeexposedenormousamountofsilicateandcarbonaterocktochemicalweathering.Steepslopeserodequickly,exposingnewfreshrock.Chemicalweathering<levelsofCO2gas,causingglobalcooling