Quote:
Originally Posted by JohnF
It is probable that once the earth was not wobbling at 23.5 degrees. Fossils of tropical animals are found at both poles, that is what is now our Polar regions were once warm. and the poles have change their position many times in the past according to the fossil record.
So that is one thing that possibly proves that we were not always at 23.5 degrees.
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It's more than probable: It's certain - (Pr=1) (as much as science can ever be).
The evidence in the scientific literature is clear on the fact that the Earth's current 23.5 degree angle of tilt (obliquity) varies over something like a 40,000 year cycle by a few degrees (±1 or so degrees). There are also other orbital changes (on much longer time scales): changes in the eccentricity of the Earth's orbit around the Sun and precession of its rotational axis.
These are all well documented variations in the earth's orbital parameters and were brilliantly pulled together by Mulitin Milakovitch, a Serbian mathematician to help explain climate change and the coming and goings of the ice ages (and as a reasonable logical extension many of the changes in between).
Best
JA