It has long been known that ice ages are mainly caused by variations in the orbital and rotational characteristics of the Earth.
Now, however, some scientists wonder if there might be a connection vice versa, too - if large changes in the Earth's climate could affect its orbital behaviour.
Let's look first at induced changes in the global climate. A contributory cause of catastrophic climate change is the fact that periodic variations in the eccentricity of the Earth's elliptic orbit sometimes cause the planet to be carried unusually far away from the sun for part of the year.
A more important influence, however, is the role of axial tilt. We all know that the Earth's axis is tilted at an angle of 23 1/2
to the plane of the Earth's orbit around the sun, but this figure is not constant: it varies from about 22 to 25. Since it is the axial tilt which gives us seasons, it follows that the amount of the tilt affects the severity of winters, and when axial tilt and orbital eccentricity combine to do their worst, we get an ice age.
Some scientists have come to the conclusion that prior to 700 million years ago, the axial tilt was not around 23 but nearer 55. They say this is the only explanation for the fact that that before that time there were glacial deposits near the equator and hardly any near the poles.
The only way this could have come about, they say, would be if the poles were getting more solar energy than the equator, which in turn happens only if the axial tilt is greater than 54. But then a funny thing happened about 450 million years ago. All of a sudden in cosmic terms, over a period of less than 100 million years, the Earth suddenly shifted its orientation to a state where the axial tilt became close to what it is today.
It is argued that the only way this could have happened so quickly would have been if a colder climate brought on a sudden ice age, and if this happened at a time when the ice accumulated disproportionately over the continents which, by virtue of continental drift, all happened to be clustered near the poles.
The local build-up of ice like this could put the spinning Earth entirely out of balance, and cause its axial tilt to lurch in the direction of its present value.
It seem like a very long shot, I admit - but I only report what they are saying in the pages of the learned journals.