Which of the following is not related to the astronomical theories of climate change?

Detailed Solution:

The correct answer is “Solar irradiance”.

The astronomical theories of climate change, also known as Milankovitch cycles, propose that variations in Earth's orbit and orientation influence long-term climate patterns.

While eccentricity of Earth's orbit, obliquity of Earth's rotational axis, and precession of equinoxes are part of the astronomical (Milankovitch) cycles affecting climate change, solar irradiance refers to the energy emitted by the sun and is not directly part of the Milankovitch theory of climate change.