Which three characteristics of Earth's orbit around the Sun vary on the timescale of Pleistocene glaciations? How does each of these affect the amount of energy received from the sun?

Question

What will be an ideal response?

Answer 1

The Earth's eccentricity (changes in how elliptical the Earth's orbit is), obliquity (the tilt of its spin axis with regard to the plane of its orbit), and precession (revolution of its spin axis about the line perpendicular to the orbital plane) all change on the timescales of Pleistocene glaciations. The eccentricity changes have periods of 100,000 and 400,000 years, the obliquity changes have a period of 41,000 years, and the precession changes have periods of 19,000 and 23,000 years. The obliquity and precession changes affect the latitudinal distribution of incoming solar radiation, whereas the eccentricity changes affect the total amount of incoming solar radiation. The changes in solar radiation due to eccentricity changes are much smaller than the changes needed to cause glacial cycles unless some positive feedback mechanism is amplifying the signal. Eccentricity does modulate the effect precession has on climate (see Fig. 14-8 and note how the envelope of the precession band expands and contracts).