ESS11
Prof.
Jin-Yi Yu
Tilt Change (Obliquity Variation)
qOver time, the tilt angle varies in a narrow
range.
qThese variations are caused by the gravitational tug
of large planets, such as Jupiter.
qThe present-day value of the tile is decreasing.
qCyclic changes in the tilt angle occur at a period
of 40,000 years.
(from Earth’s Climate: Past and Future)