Ancient North American droughts were driven by Earth’s orbital shifts, study from the University of Helsinki finds.

These orbital variations, known as Milankovitch cycles, describe how Earth’s path around the Sun changes over tens to hundreds of thousands of years. These changes influence the amount of solar ...

Climatic changes of the last 18,000 years ... Monsoon climate of the early Holocene: Climate experiment with the Earth's orbital parameters for 9000 years ago. Science 214, 59-61 (1981).