[dangus]

Yes, it is ridiculous. There is a perfectly valid control study for the effect of a collapse of the thermohaline circulation: the Pacific Northwest. (I’d also suggest Patagonia and New Zealand, but the researchers I’ve read didn’t, so maybe there’s something I don’t know about affecting circulation there.)

>>During the last ice age they know that the warm currents were diverted further south which affected the weather and rain patterns worldwide. <<

Yes, but that’s not the same as causing the ice age. What it actually did is make the Middle East more fertile, for one.

>> That along with the slight difference in the earth’s angle to the sun caused dramatic cooling effects in the northern hemisphere. <<

That certainly is why the ice age was “lopsided” to the North, but doesn’t explain its occurence in the first place. The truth is that we don’t even know whether ice ages are caused by solar, orbital or planetary variations. One researcher noted that the Earth tends to have ice age cycles when there’s a continent over one pole, but couldn’t explain why that would cause an ice age, or why the ice ages came in cycles.

>> It’s not global warming, just a recurring earth cycle. <<

Actually, it’s a lot of nothing. It’s 0.7 degrees over an entire century. The question is whether its indicative of a growing trend, or whether its a little tiny blurp.

[JasonC]

"One researcher noted that the Earth tends to have ice age cycles when there’s a continent over one pole, but couldn’t explain why that would cause an ice age, or why the ice ages came in cycles" Milan. cycles change the average energy delivered over a year in the two hemispheres. If there is land at one of the poles and a Milan. cycle reduces the energy delivered to that pole to a minimum, a thick ice cap can form over that pole. In itself, not yet any big deal, because average energy delivered to the other pole rose, net energy was unchanged. There was just an energy transfer between the hemispheres, and some of the shortfall side was "stored" as thickened ice over one pole.

But now, go through the cycle until inclination is high, rather than "standing upright". The iced pole is now rotating through effectively lower solar latitudes. The ice is much shinier than the rest of the earth, so it reflects a large portion of its solar inflow to space immediately. Let the whole cycle go through with maximum energy hitting the iced hemisphere, but failing to melt the thick ice cap.

Then the other hemisphere was cooling, as it was the opposite end of the Milan. cycle. And the integral of incoming energy that "faced" the highly reflective portion of the surface was at its height. Thus there is a net energy loss to the whole earth, not just a shift of which hemisphere it went into, when.

We have an albedo feedback. Ice at very high latitudes with the earth standing upright has no serious effect on net incoming solar over a year, because the incoming energy is weighted towards the equator. But let there be persistent ice at lower latitudes with the earth tilted, and the icey regions pass through serious solar and seriously reduce the net energy coming in.

That is the connection I can see between Milan. cycles, land at a pole, and ice ages.

FWIW...