The earth goes through several cyclical changes in climate that depend on several factors
1. Orbital Eccentricities (Milankovitch Cycles). The orbit of the earth around the sun changes from circular to elliptical on a 100,000-year cycle. When at its farthest, there is cooling and it fuels glacial conditions. There is less ice and snow now than at any time in the last 120,000 years. Glacial conditions are expected to start in about 37,000 years.
2. Earth’s Spin Axis. It fluctuates between 21.5° to 24.5° and back every 45,000 years. It is now 23.5°.
3. Wobble. The tilt and eccentric orbits create a wobble of the spin axis in cycles every 23,000 years.
4. Warming secondary to CO2. The present temperature is higher than at any time in the last million years. This is delaying the onset of cooling and the next ice age.
