The explane the Milankovitch Cycles, and why they are not a far more likely source for global warming and cooling than man made CO
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http://www.gly.fsu.edu/~kish/dynamic/global/LAS.htm
Orbital shape (eccentricity)
Axial tilt (obliquity)
Precession (axial rotation)
The external controls of the Earth's climate can be summed up in the list below:
External Factor How Climate is Affected
Milankovitch Cycle The amount of solar radiation
*Eccentricity of orbit entering atmosphere varies
*Obliquity of axis with change of Earth's position
*Precession of axis
Total Solar Output The amount of solar radiation
leaving the sun varies
Thomas (2002) states,
"The eccentricity influences seasonal differences: when the Earth is closest to the sun, it gets more solar radiation. If this occurs during the winter, the winter is less severe.
If a hemisphere has its summer while closest to the sun, summers are relatively warm."
Currently the difference between closest approach to the Sun (perihelion) and furthest distance (aphelion) is only 3.4% (5.1 million km). This difference is equivalent to about a 6.8% change in incoming solar radiation. Perihelion presently occurs around January 3, while aphelion is around July 4. When the orbit is at its most elliptical, the amount of solar radiation at perihelion is about 23% greater than at aphelion. This difference is roughly 4 times the value of the eccentricity.
So why should we accept Man Made Global Warming as fact?