Tate
Ah. Apologies; since you had just said that, I thought that it was one of your articles. — unenlightened
No. I was just killing two birds with one stone: contributing to this topic and preparing to edit a poorly written Wikipedia page. That page used sources that misquoted other sources. Not good.
If you want, we could talk a little bit about the present major ice age, sometimes called the Quaternary. We can discuss theories about why it happened. The Wikipedia articles for that are pretty good, so I'll reference them.
To review:
Major ice ages, as we discussed, happen for a variety of reasons.
In the case of the Quaternary, for some time now the leading theory has been about a change in ocean currents which happened about two and a half million years ago. It is true that atmospheric CO2 is down about 90% from what it was before the Quaternary, but that may be a positive reinforcing side effect as opposed to a cause. Cold water holds more CO2 than warm water, so as the ocean currents changed to cool the surface, the oceans started pulling in CO2, cooling the world further.
From
here:
An important component in the development of long-term ice ages is the positions of the continents.[16] These can control the circulation of the oceans and the atmosphere, affecting how ocean currents carry heat to high latitudes. Throughout most of geologic time, the North Pole appears to have been in a broad, open ocean that allowed major ocean currents to move unabated. Equatorial waters flowed into the polar regions, warming them. This produced mild, uniform climates that persisted throughout most of geologic time.
"But during the Cenozoic Era, the large North American and South American continental plates drifted westward from the Eurasian plate. This interlocked with the development of the Atlantic Ocean, running north–south, with the North Pole in the small, nearly landlocked basin of the Arctic Ocean. The Drake passage opened 33.9 million years ago (the Eocene-Oligocene transition), severing Antarctica from South America. The Antarctic Circumpolar Current could then flow through it, isolating Antarctica from warm waters and triggering the formation of its huge ice sheets. The Isthmus of Panama developed at a convergent plate margin about 2.6 million years ago, and further separated oceanic circulation, closing the last strait, outside the polar regions, that had connected the Pacific and Atlantic Oceans.[17] This increased poleward salt and heat transport, strengthening the North Atlantic thermohaline circulation, which supplied enough moisture to arctic latitudes to create the northern glaciation.[18]"