Earth scientists at Utrecht University and University of Geneva have shown for the first time that the Earth’s climate was subject to regular changes 2.5 billion years ago, when conditions were fundamentally different from those today. The changes were due to periodic fluctuations in the shape of Earth’s orbit. They published their findings on 8 April in the leading journal, Nature Geosciences.

Milankovitch cycles

The shape of Earth’s orbit and the orientation of its axis undergo regular fluctuations over periods of many thousands to millions of years. The fluctuations, known as Milankovitch cycles (after the Serbian geophysicist Milutin Milankovitch), have a major effect on the distribution of sunlight over the planet’s surface, and consequently on climate.

Astronomically induced climate changes of this kind have been recorded in the Earth’s geological record of the past hundreds of millions of years, in the form of highly regular patterns of successive rock strata. Scientists have studied these in detail, enabling the changes to be identified precisely.