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USGS CMG InfoBank: Ice Ages

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Comment: 12:48 - 14:04 (01:16)
Source: Annenberg/CPB Resources - Earth Revealed 23. Glaciers
Keywords: "J. Lawford Anderson", glacier, "glacial ice", "glacial cycle", "geologic time", "Earth's orbit", Sun, "Earth's rotation", "global cooling"

Our transcription: The repetitive nature of ice ages during the past two million years suggests that the world may again be moving toward a period of deep freeze.
This is not likely to begin within our lifetimes, but may commence within the next few thousand years.
Most scientists believe ice ages are tied to changes in the position of Earth as it orbits the sun.
As the Earth rotates, if occasionally it tilts a bit, then a good portion of the Earth will undergo sudden cooling.
We know that happens.
Another change occurs, and we know this happens as well, with a not perfect revolutionary period of the Earth's rotation around the sun, it's more elliptical, and in certain stages it becomes more elliptical than other times.
We know that happens.
The theory for the global cooling of the Earth and the formation of the ice age is that on occasion both the wobble and noncircular rotation or revolution of the Earth's passage around the sun occur together.
And we get global cooling that is unique to that time.

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