Environmental HistoryWhat causes “natural” environmental

change?

Environmental HistoryWhat causes “natural” environmental

change?

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Environmental HistoryWhat causes “natural” environmental

change?

Environmental HistoryWhat causes “natural” environmental

change?

External Changes1. Solar luminosity2. “Slowing” of Earth’s rotation3. Earth’s orbit4. Magnetic field 5. Meteorite/comet impacts

Solar LuminositySolar Luminosity

Earth’s Rotation & the Moon

Earth’s Rotation & the Moon

OrbitalChangesOrbitalChanges

Magnetic FieldMagnetic Field

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Meteorite/Comet Impacts

Meteorite/Comet Impacts

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Environmental HistoryWhat causes “natural” environmental

change?

Environmental HistoryWhat causes “natural” environmental

change?

Internal Changes1. Plate tectonics2. “Natural disasters”3. Atmospheric changes4. Climate change5. Rising & falling sea level

Plate TectonicsPlate Tectonics

Plate TectonicsPlate Tectonics

Earth’s “surface” is broken into plates

Plates move“Geology happens” where the plates interact with one another

Growth of ContinentsGrowth of Continents

“Natural Disasters”“Natural Disasters”

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Atmospheric ChangesAtmospheric Changes

ClimateChange

ClimateChange

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Sea LevelChanges

Sea LevelChanges

So why are we concernedabout “human” changes?So why are we concernedabout “human” changes?

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ImPaCT(Ehrlich & Holdren)

ImPaCT(Ehrlich & Holdren)

Human Impact (Im) =

Population (P) x Consumption (C) x Technology (T)