Name: Richard
Status: Educator
Age: 40s
Location: N/A
Country: N/A
Date: September 12, 2002
Question:
Many theories exist about what caused the many "Ice ages"
that the earth has experienced. Some people say we are still in an ice
age, but that we have just been in a warming trend for the past few
thousand years. My question is this: How much influence does the
fluctuating orbit of the earth and the gradual change in the tilt of the
earth's axis have on the cyclical ice ages the earth has been
through?
And secondly, do we have cause to believe that the great ice
sheets (glaciers) may return fairly soon?
Replies:
Whether we are expecting "global warming" or a "great ice age" seems
to depend upon whose crystal ball you choose to look into. In any case "ice
ages" occur on geological time scales, so none of us will have to worry
about it. We will all be long gone.
Vince Calder
Richard,
You may want also to look up the answer that I gave concerning the orbit and
tilt of the Earth in the NEWTON archive. However, most climatologists
agree that the orbit
and especially the tilt have a significant effect on climate and thus on
the cyclical ice ages.
Some Penn State scientists have hypothesized that the tilt of the Earth may
have been as much as 54 degrees at one time and it slowly changed to the
present
23 degrees as huge ice sheets formed and melted, and changed Earth's shape over
the past 150 million years. This theory would help to account for tropical
fossils appearing in polar areas.
David R. Cook
Atmospheric Research Section
Environmental Research Division
Argonne National Laboratory
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