What Caused Past Co2 Rises?

What caused CO2 rises, in the very distant past? Volcanic activity? Thanks for any answers on this question.

[aslkahuna]

Initially the increases noted in the past are triggered by the Atmospheric response to the Milankovitch cycles that result in the glacial/interglacial periods. It is mainly CO2 that has been sequestered that is being released as things warm up. If you look at the peak CO2 levels however, you will noticed that they reach a peak of around 300 ppm and no higher suggesting a natural upper limit. Currently we are some 35% above that natural limit and still going up. By doing an isotopic analysis it is possible to determine where that excess CO2 is from and that analysis shows that it comes from the use of fossil fuels. It is this EXCESS that's the source of concern and not the overall level since we know how the atmosphere responds to the natural variability but have no clue as to how it will respond to the excess levels though there are many people willing to guess some guesses based upon a reasonable amount of facts and others being pulled out of someone's fundamental pore.

Steve

[BigNeerav]

Al Gore and his moron minions would say humans, but they are once again in the dark!

[Martinsville Weather]

Based on those charts that keep showing up...temperature rises apparently caused the CO2 rises.

[BigNeerav]

Based on those charts that keep showing up...temperature rises apparently caused the CO2 rises.[/b]

This reminds me of solution chemistry, where the higher the temperature of a solution, the more stuff it can hold. If we think of the earth's atmosphere that way, then we can understand why what you say happens, but we should also take into account that there is a feedback mechanism that will keep this vicous cycle going indefinitely...

Check our my greenland thread guys. It's pretty interesting if you ask me.