1.Volcanic eruptions can cause short-term climate change by cooling the earth, as the ash blocks out the sun.
2.A cycle of precession in the earth's orbit can initiate gradual climate change over a period that lasts 26,000 years
3.Climate change can also be initiated by the cycle in which the earth's elliptical orbit rotates
4.The angle between Earth's rotational axis and the normal to the plane of its orbit oscillates between 22.1 and 24.5 degrees on a 41,000-year cycle. This can affect the seasonal variation of climate.
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