What are 3 major milankovitch (orbital) cycles of eccentricity, tilt, and precession?

Question

Why does each cycle affect global climate?

Answer 1

eccentricity - variation in how elliptical the earths orbit around the sun is. With high eccentricity, the earth comes closer to the sun during part of the year, and is further away at the opposite end of the year. The main periodicity is 413,000 years.

tilt - wobbling of the earths rotational axis over a couple of degrees. With relatively high tilt, both hemispheres receive more radiation from the sun in summer, and less in winter. Hence you have hotter summers and cooler winters. Periodicity is around 40,000 years.

precession - change in the orientation of the Earths rotational axis relative to the Sun. At one end of the cycle, the northern hemisphere will have strong seasons and the southern hemisphere mild seasons. At the other end of the cycle, it will be the opposite. Periodicity is about 20,000 years.