Upper-atmosphere carbon dioxide is altering satellite orbits

Ars Technica : The outer layer of Earth’s atmosphere, the thermosphere, contracts as it cools. When it contracts, satellites in orbit on the edge of it experience less drag and move more quickly. The phenomenon was widely noted in 2010 when cooling occurred due to the less active Sun, but the effect couldn’t fully explain the cooling. It was thought that carbon dioxide acted as a coolant in the thermosphere by absorbing energy from oxygen molecules and then radiating the energy out of the atmosphere as heat. An examination of data collected by the Canadian SCISAT-1 satellite showed that carbon dioxide concentrations in the thermosphere increased by 23.5 ± 6.3 ppm over the past decade. The increase is greater than expected and suggests that more mixing is occurring between the various layers of the atmosphere than was previously thought.