Why is it important for Earth’s magnetic field that the inner core is hotter than the outer core?

The inner core provides the heat source for outer core convection.

The inner core’s heat produces the Coriolis effect needed for rotation.

The inner core’s heat allows the outer core to conduct electricity.

The inner core provides the energy for Earth’s orbit around the Sun.

Explanation:

the rub-al-khali is also known as the arabian desert and the "empty quarter"