qOrbital-scale climate changes are caused by subtle shifts in Earth’s
orbit.
qThree features of Earth’s orbit around the Sun have changed over
time:
q (1) the tilt of Earth’s
axis,
q (2) the shape of its yearly
path of revolution around the Sun
q (3)
the changing positions of the seasons along the path.
qOrbital-scale climate changes have typical cycles from 20,000 to
400,000 years.