Space/Science — HabitableZone

Space/Science » in reply to Thanks, TB.

"runaway" greenhouse effect
TB — (archived)

As others have mentioned, there is no danger of any "runaway" greenhouse effect.

If you pull the camera back a ways, you can see that CO2 has been one hell of a lot higher than it is now, and we haven't turned into Venus yet.

http://www.net33.com/images/earth_co2_temp_history_millions.gif


The time frame we usually see goes back only about half a million years.

http://www.daviesand.com/Choices/Precautionary_Planning/New_Data/IceCores1.gif


The correlation between temperature and CO2 is obvious, but cause and effect is not, particularly at these time scales.

The question I've never gotten a good answer for is, if CO2 drives the temperature, why should the spikes ever go down? We have to postulate a recurring mechanism that, if it the environment gets hot enough, suddenly causes CO2 to start falling, and keep falling, as temperature falls after it. Anybody got one?

On the other hand, if rising temperatures cause the increased CO2, one can think of astronomical and other influences that could cause temperatures to rise and fall, particularly in a cycle. One can also think of mechanisms where the ambient temperature could change CO2 uptake or emission from the natural environment.

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