Abstract
After a brief discussion of the secular variations of the climate of the earth, the following theories, proposed for the explanation of these variations are described. None of these theories is sufficient to account for the known variations of climate, and some require dynamical conditions which are not in accord with celestial mechanics. These theories are:
The effect of the temperature of the interior of the earth.
Emanations of radioactive substances in the earth's crust.
Variations of solar energy according to Russell's theory of stellar evolution.
Variations of the inclination of the earth's axis (precessional motion and variations of latitude).
The “pendulation” theory.
Variations in the carbon dioxide content of the air.
Volcanic action; dislocation of parts of the earth's crust: distribution of sea and land.
Cosmic causes.
It is concluded that no single theory is likely to be the right one. but that the factors represented by several combine to give the known secular variations of climate.
