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Earth 2
Tuesday, February 23rd, 1999
Announcements:
Lecture notes:
Faint Early Sun Paradox
- Solar Physics--sun was .7-.8 of what it is today
(during the Archean Time Pd.)
- Climate Models--Earth should be frozen
- Geologists--say there is life and running
water...therefore the composition of greenhouse gases was
higher, CO2 was stable in the atmosphere, and volcano
input which puts CO2 into the atmosphere creating CaCO3
(600x's the amount needed)
Lessons
- Even with reduced sun (.75 solar output), the planet
still has life...implies remarkable stability
- Greenhouse Effect...explains the CO2 in the atmosphere
- Energy Equation Balance...used to determine factors
affecting Archean Time Pd
Problem: Sun's output is increasing. If CO2 is high, why
didn't the earth explode?
Input: Volcano
Ouput: Rockweathering
- Mechanically Degrading...1) Erosion by
water 2) Cracked by ice
- Chemically Degrading...1) Making
surface/soil acidic & it eventually erodes away @
rock
Feedback
- When igneous rock is chemically
weathered, CO2 is consumed
- When limestone is chemically weathered,
there is no net change
- The product of weathering igneous rock is limestone and
quartz
Soil
- Warm, wet soil --> INCREASED chemical weathering,
which removes CO2
- Cold, dry soil --> DECREASED chemical weathering, slow
CO2 removal
Lessons
- Potent Negative Feedback (Climate --> Rock Weathering
--> CO2)
- Remarkable Stability in the LONG TERM
- Takes billions of years
- If you kick the earth hard, it recovers
- CO2 is a major factor in the earth's stability
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