Forget all that you tell me in your opinion what is the driver for glaciation?
Forget all that you tell me in your opinion what is the driver for glaciation?
Have I ever in the past referred you to my profile, point #5?
First of all, I won't be able to continue this, and for that I apologize. I made the recent mistake of replying to a post here on global warming. The temptation of trying to correct the repeated misstatements and misunderstandings I read here over and over again is very strong, and I have to remember and remind myself that all of my efforts were, and are going to be, essentially futile. So I will shut myself up, aided by the fact that happily I won't be able to touch a computer for two weeks*, and I am really, really slow at typing text on a standard phone keyboard (no, I don't have an Iphone).
*(wish I was going to Iceland, but I'm actually only going back to Wisconsin)
So the short (I'll do my best) answer to your question is that the "driver" of continental glaciation, i.e., the main thing that causes glacial periods, is low atmospheric CO2 concentrations. The reverse of that is, the main thing that causes interglacial periods is high (speaking Pleistocenically) CO2 concentrations. The difference of about 100 ppm CO2 between glacials and interglacials is the primary factor affecting the radiative balance that can accomplish the approximate 5 degree difference of global temperatures between glacials and interglacials. Note that the entire change is a combination of radiative forcing and feedback, with water vapor concentration (relative humidity) being the main feedback.
(hi palmer)
Nothing else in the Earth system can do this. Repeat, nothing else. Which means anything which could have plausibly influenced the Earth's climate over the entire Pleistocene. The only thing that can accomplish the necessary temperature change is radiative forcing due to atmospheric CO2.
But if you'll note in point #5 in my profile, the triggering factor is maximum and minimum insolation, caused by Milankovitch solar forcing. The insolation maxima and minima induce the necessary change direction in the climate state. CO2 atmospheric concentrations start to rise or fall in response to this trigger (depending on the direction of change) and over the ensuing millenia, bring the process to completion. Until the next trigger to reverse the process.
This is not my little opinion or theory. What I just summarized is scientifically accurate (though quite cursory), based on numerous investigations, a broad range of data, and all manner of interpretation and analysis.
So that's why when I see the ridiculous statement that atmospheric CO2 isn't a climate factor, I cringe. It's just wrong. Beyond the Pleistocene, there are events in deeper (i.e. older) paleoclimate that demonstrate without doubt how radiative forcing by atmospheric gases (notably CO2, but with help from methane and SO2) affects climate and global temperature. (As an aside, why do people accept with little question that SO2 aerosols from volcanic eruptions cool climate, but have a problem with increasing CO2 concentrations warming climate? Is it because one is just simpler to understand than the other and easier to observe on shorter-term time-scales?)
So there you go. That's my answer.
One more aside. I've recently been pondering why the Maunder Minimum (low sunspot numbers indicating lower solar activity, causing the Little Ice Age, probably) actually caused lower global temperatures, because the actual change in solar activity was small. I surmised that this was due to the small change causing larger climate feedbacks. Turns out that was basically right; other people have thought about this and done research and wrote papers about this.
I won't have time to read these before I'm gone, so this will help me find them when I get back.
I hope what I wrote was useful. I always hope that.