The three orbital parameters that control the amount and seasonality of insolation are eccentricity, tilt, and precession. The shape of the orbit varies every 100,000 years from nearly circular to an eccentric ellipse. Eccentricity variations change the average Earth-sun distance such that annual insolation at the Earth's surface changes.
Greater tilt angles cause more increased seasonal extremes.
The wobble of the earth's rotation has a double periodicity of 23,000 and 19,000 years. This situation changes with time.