The atmosphere is constantly changing. Its composition has varied regularly over the course of the planet’s climatic epochs, particularly with regard to its levels of carbon dioxide (CO2) concentration, a crucial factor in determining Earth’s climate. The atmosphere is constantly changing. Its composition has varied regularly over the course of the planet’s climatic epochs, particularly with regard to its levels of carbon dioxide (CO2) concentration, a crucial factor in determining Earth’s climate. Earth Sciences Environment Phys.org – latest science and technology news stories