Oribital forcing or climate change due to shifts in the Earths elliptical orbit around the sun every 100 000 year (eccentricity), from an elliptical orbital to almost circular. There is also precession where the Earth wobbles like a top. One cycle takes approx 26ka. Finally there is obliquity which involves the tilt of the earth. The Earth currently has an axial tilt of about 23.4 and does vary from 22.1 and 24.5. As you probably know it is the tilt of the Earth which provides us with the seasons by varying the insolation or solar radiation (sunlight) striking the Earth because of the angle it comes in at. This cycle is about 43ka. These 3 cycles put together are called the Milankovitch cycles and correspond extremely with with the major glacial and warming periods. It does not explain all climate change such as in the Younger Dryas where a warm period about 12 000 years ago (between 10,800 and 9,500 BC) was interupted by a cold snap which lasted
about 1300 years. An asteroid impact was believed responsible for this. Other cooling periods have been caused by volcanic activity such as the Siberian Traps where volcanic activity lasted over a million years flooding most of what we call Siberia in basalt a volcanic rock.
Edited by VenomFangX, : Part badly written, seemed I was only talking about one of the cycles and not all of them.
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