The effect of Earth precession angle on a climate is presented here. It is shown that the glaciation epochs occurred only when the precession angle was low. After the continental glaciation formed in the Northern hemisphere, Earth’s spherecal symmetry was disrupted and its precession angle increased drastically. As a result, a drastic and rapid climate warm-up occurred, the glaciers melted down and an interglacial stadial¹ began. Subsequently, affected by the Lunar-Solar gravity pull on the Earth’s equatorial swelling, the precession angle gradually decreased and a new cooling-down phase occurred. As a result, there was nonlinear oscillation of Earth’s climate with periods on the order of 100 - 120 MY.