Cycles

This encompasses most of the theories surrounding 2012, but are these really theories? All except for Planet X and Black Holes, have happened in our history, be it recorded or scientific research. This is not to try and create mass hysteria, but this is fact proven many times over, and anyone with the proper knowledge can attest to this. How 2012 falls in to these cyclic patterns above in fact is a cycle, or pattern of change. Sometime this is good, and other times bad. We can only look at out past history, the history of the Earth to formulate a hypothesis of things to come. The main reason people put the Mayan calendar with the 2012 theory is simple, and understandable, but no real proof or break through's have been. Because the Earth has been around for millions of years, cycles that affect us today are relatively miniscule compared to the big picture. Ice Ages come and go, this is proven, but what triggers these are still mysterious to us even today. There are even indication that the planet went into an Ice Age within a few hours due to a Supervolcano that erupted and clouded the sky. So in short, there are cycles greater than what you may have come to understand, or even believe, but again we are just talking about the Earth. Outside or atmosphere and even our Galaxy, there are many wars being waged between one Galaxy and another, another cycle.

Milankovitch cycles are the collective effect of changes in the Earth's movements upon its climate, named after Serbian civil engineer and mathematician Milutin Milanković. The eccentricity, axial tilt, and precession of the Earth's orbit vary in several patterns, resulting in 100,000-year ice age cycles of the Quaternary glaciation over the last few million years. The Earth's axis completes one full cycle of precession approximately every 26,000 years. At the same time, the elliptical orbit rotates, more slowly, leading to a 21,000-year cycle between the seasons and the orbit. In addition, the angle between Earth's rotational axis and the normal to the plane of its orbit moves from 22.1 degrees to 24.5 degrees and back again on a 41,000-year cycle. Currently, this angle is 23.44 degrees and is decreasing.

The Milankovitch theory of climate change is not perfectly worked out; in particular, the largest observed response is at the 100,000-year timescale, but the forcing is apparently small at this scale, in regard to the ice ages. Various feedbacks (from carbon dioxide, or from ice sheet dynamics) are invoked to explain this discrepancy.

Milankovitch-like theories were advanced by Joseph Adhemar, James Croll and others, but verification was difficult due to the absence of reliably dated evidence and doubts as to exactly which periods were important. Not until the advent of deep-ocean cores and a seminal paper by Hays, Imbrie and Shackleton, "Variations in the Earth's Orbit: Pacemaker of the Ice Ages", in Science, 1976, did the theory attain its present state.