Originally Posted by franksargent
I don't dispute your first statement. The flux of human CO2 versus the natural flux is indeed a few percent.
Where I think we differ, is in the causes of past CO2 changes versus the current CO2 changes. Maybe I'm mistaken, and I need to read up on it some more!
Anyway, WRT past histories of CO2, my understanding is the Earth's orbital motions are one natural source of temperature changes, that these temperature changes lead to CO2 changes (lags), but that at some point CO2 feedback causes further temperature changes.
You are not mistaken. CO2 does cause a heat increase. However, to what degree this happens is unknown.
It isn't hugely significant, however, because we've had similar CO2 and heat spikes before. If CO2 causes large heat spikes, since heat spikes also cause CO2 spikes, the world would have ended up stuck in a position of extreme amounts of CO2 and extreme temperatures. Obviously, since we're all here today, this hasn't happened.
CO2 is important to look out for because, if the temperature does increase too much, atmospheric-CO2-reducing methods are a possibility in the future—it's a possible escape from global warming. But it alone cannot possible have caused current global warming.
In terms of the recent changes in atmospheric CO2, everything I have read suggests that these are anthropogenic in origin, and not due to changes in Earth's orbital motions or other natural causes. So that now the CO2 increases occurring will act as a feedback mechanism that causes the temperature to increase in a lagged fashion.
Everything i have read indicates most scientists feel that it is at least partly anthropogenic in origin. However, I don't think a single scientist ever pointed out that it was ONLY anthropogenic in nature.
So what was a driver in the past, is not the same as the current driver.
Past: Natural causes of temperature increase >> Lagged CO2 increase >> Further temperature increases due to GHG/CO2 feedback effect.
Present: Anthropogenic emissions cause increased concentrations of atmospheric CO2 >> Further temperature increases due to GHG/CO2 feedback effect.
This is what I was trying to point out before. Current CO2 is almost entirely because of the Medieval Warm Period, with extra contributions from humans.
The same driver as in the past is driving this time, but now we have an extra turbocharger from humans that's giving it a bit of a boost.
However, we still don't how much temperature is increased due to CO2, and therefore if humans are or are not significant. More importantly, we don't know how much the temperature will increase on its own, which is of more concern to me at the moment. Finally, we don't really know exactly what the full effects of the warming will be.
A lot of people talk about how there's a "global warming conscensus," and there absolutely is: very few people deny temperature increases worldwide.
However, that doesn't mean that every global warming study is correct, and it doesn't mean that there aren't more questions than answers right now.
If I'm totally off base in this please provide some bona fide links from peer reviewed scientific journals, or at the very least some links at RealClimate.
Again, I could be mistaken, but I believe that all the GCM's support these CO2 temperature feedback effects.
That is all.
You're not off base at all, you're just a tad obsessed with placing a blame for global warming when most scientists are hoping to find a solution, or at least a more accurate idea of the effects, regardless of why it's happening
That said, you need to branch out a bit from RealClimate. It's very accurate, well-written, and I haven't found anything there that is flat out wrong; it's also really biased. It's the truth, and nothing but the truth, but it's not the whole truth.
For me, I cherry pick from both sides. ClimateAudit.org is also a very good site, although less well organized. If you see an argument that seems weak, check it out on the other site, and see what they have to say. Between the two of them, you'll generally find what you want.