Milankovitch cycles: a fancy name for a simple concept

Milankovitch cycles: the slow dance of the Earth

The movement of the Earth around the Sun is not always the same. Thanks to long term studies, scientists – in particular the Serbian mathematician and geophysicist Milankovitch – have defined a solid framework that could explain the orbital motions: the Milankovitch cycles. Here are the elements observed by Milankovitch: the shape of the orbit, its obliquity and the direction that Earth’s spin axis is pointed. They all change slightly in time: the Earth’s orbit shape varies between being a perfect circle to being slightly elliptical. The obliquity changes the angle, and the precession rotates. These periodic motions seem to happen in predictable cycles that according to Milankovitch theory affect the amount of sunlight and energy that Earth absorbs from the Sun. 

The Milankovitch cycles do not explain the current climate change

The changes that occurred over the past 2.5 million years cannot be understood within the framework of the Milankovitch cycles: Ice Age happened within a frame of thousands to hundreds of thousands of years. The changes we are experiencing are way too rapid to be explained within the logic of the Milankovitch cycles: over the last 150 years Milankovitch cycles have not significantly changed the amount of solar energy absorbed by Earth. The melting of ice caps and the increase in concentration of human-made carbon dioxide in our atmosphere is responsible for changing the atmospheric composition over the last 100 years, rather than climate feedback from the Earth caused by the Milankovitch cycles.