Quote:
Originally Posted by onon
The last decade is the best example - co2 levels are rising at only about half of human emission rate. Without human emissions co2 levels couldn't be rising.
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Is ten years really an effective time frame to base geologic conclusions upon?
Quote:
Because nature is absorbing more co2 from the atmosphere than it is emitting into it. Therefore left alone co2 levels in the atmosphere would start falling. They only rise because human co2 emissions (~28 billion tons per year) are double the net rate of natural absorption (~15 billion tons per year)
The reason nature is absorbing more co2 than it is emitting is because there is an abundance of co2 in the atmosphere at this time.
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Post hoc, ergo propter hoc.
CO2 concentrations fluctuate naturally. Therefore, there must be some mechanism by which CO2 concentrations increase naturally. Therefore, it is possible that CO2 concentrations are increasing naturally. Definitive statements like the one I quoted are therefore false.
Furthermore, you're arguing that CO2 concentrations are increasing because humans are emitting CO2. You argue that nature sequesters more CO2 than it emits, and further claim that this is because there is "extra" CO2 in the atmosphere. You then conclude, erroneously, that were there no human emissions, CO2 concentrations would fall. This conclusion does not follow from your premises.
If the only reason nature is absorbing more CO2 than it emits is because humans are emitting CO2, and you took humans out of the equation, then nature would not be absorbing more CO2 than it emits. CO2 concentrations would remain stable. Yet, CO2 levels have not remained stable (in any real geologic sense) for the entire history of this planet.
In reality, you can't say with any certainty why CO2 concentrations are increasing, nor whether removing human emissions would have either a positive or negative net effect.