Australasian Science: Australia's authority on science since 1938

A Different Angle on Earth’s Climate History

Credit: pongpongching/Adobe

Credit: pongpongching/Adobe

By George Williams, Phillip Schmidt & Grant Young

Earth’s axial tilt affects our environment in many ways, but a much greater tilt in the remote geological past may have strongly influenced the planet’s climate history and the evolution of life.

The full text of this article can be purchased from Informit.

Do you know what controls:

  • the seasons, with warm summers and cool winters in middle latitudes, large seasonal temperature changes in high latitudes, and a consistent equatorial climate?
  • the meridional temperature gradient, which runs north–south and explains why Darwin is warmer than Hobart, and why high latitudes have ice sheets while the equator is hot?
  • the general direction of global oceanic circulation?

These important features of the environment are controlled by the tilt of Earth’s spin axis relative to the perpendicular to the plane of Earth’s orbit around the Sun. This tilt is termed the obliquity of the ecliptic, and it varies between 22° and 24° over a cycle of 41,000 years (ka).

For the present-day obliquity of 23.4°, global seasonal temperature variation is mostly moderate, with the poles cold and the equator hot. The meridional temperature gradient controls the general direction of oceanic circulation, with cold, dense water sinking...

The full text of this article can be purchased from Informit.