Heat from Earth's Core
Heat constantly migrates from the core of the earth to the surface. This heat keeps lakes from freezing solid, after ice forms on the surface. It keeps the ground from freezing more than six feet deep in the winter. It causes deep well water to be hot, which can sometimes be used for geothermal heating.
Therefore, the cause of global warming could be oceans increasing in temperature due to increased heat flowing from the earth's core. The increased heat could be due to a hot spot which rotates in the molten fluid within the earth. As it rotates, it could get closer to the surface in an area where the heat can diffuse into the oceans.
Or it could be the central core being pulled closer to the surface due to gravitational forces in the solar system related to changes in the earth's orbit. The central core of the earth is highly dense, consisting largely of iron, which would cause it to respond to gravitational forces. Magnetic north constantly migrates demonstrating that masses move around in the molten fluid within the earth.
http://nov55.com/gbwm.html
http://www.canadafreepress.com/2007/global-warming051407.htm

not sure about the reading on these articles but I am curious as to what everyone would say about the ideas.