Introduction to special section on Long-term Changes and Trends in the Stratosphere, Mesosphere, Thermosphere, and Ionosphere



[1] It has been over 20 years since Roble and Dickinson [1989] first concluded that global change will occur in the upper atmosphere (above 50 km) as a result of increased greenhouse gas concentrations within this region. Long-term changes to Earth's atmosphere are becoming more and more relevant to the future of our world, and it is vital that we quantify and understand changes occurring at all levels within the coupled atmospheric system. The increasing concentration of greenhouse gases, stratospheric ozone depletion, slowly varying solar and geomagnetic activity, secular change of Earth's magnetic field, and changing dynamics propagating up from the troposphere are some of the possible causes of long-term changes in the stratosphere, mesosphere, thermosphere and ionosphere.