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Why
does Venus have much more CO2 in
atmosphere than Earth?
•Amount of CO2 in
atmosphere on Venus
roughly equal to
amount of CO2 in limestone on Earth
amount of CO2 in limestone on Earth
•With no oceans, don’t have a way to get CO2 out of
atmosphere and back into
rocks
•Runaway effect, because high T causes faster loss of water to space.
–If H2O gets into upper atmosphere it is broken down into O, H by UV sunlight
–H is so light it escapes to space
–On Earth cooler T traps H2O in lower atmosphere (it condenses if it gets to high)
•Location
closer to the sun pushed Venus “over the edge” compared to Earth
From our text Horizons, by Seeds