Geo 105, Back to Geologic Variations in CO2, Temp, & Mass extinctions
CO2 variations -- recent
- observations of carbon dioxide in atmosphere show that it is increasing over the past hundred years or so
- also, global temperature is increasing (not as easy to see) over the past several decades.
- is it good or bad?
CO2 variations -- over geologic time
- Recall the figure in your book that shows estimates of CO2 over the past 600 ma (million years), it has varied a lot, but does life simply adapt to these long-term variations with no ill effects?
- One extreme test of the effects of CO2 variations is to see if its correlated with mass extinction events
Mass extinctions
The geologic record indicates Five Big Extinction Events in the past 600 ma
- The "K-T boundary" event, at about 70 ma ago
- "end of the Triassic", at about 210 ma
- "end of the Permian", at about 250 ma << The Big One
- "late Devonian", at about 360 ma
- "end of the Ordovician", at about 430 ma
Do you see any correlation to the CO2 curve?
I don't. Perhaps the mass extinctions are where the CO2 changes quickly?
If not CO2 (hence temp), then what causes mass extinctions?
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