The Impact of 21st Century Source Gas Changes on the Upper Stratosphere

It is expected that future changes in the concentrations of surface source gases, including N2O, CH4, CO2, and chlorofluorocarbons, will impact stratospheric composition and dynamics. In this study,we use the GSFC two-dimensional chemistry and transport model to investigate the impact of these source gases on the middle and upper stratosphere during the 21st century. Specifically, we ran several model simulations in which these source gases are varied one at a time in order to assess the impact of each source gas individually. These are then compared with a complete simulation in which all source gases are allowed to vary simulataneously. In this way we examine the relative impact of each source gas on future changes in stratospheric ozone, water vapor, temperature, and age of air. We also derive sensitivity factors of these quantities to the variations of each source gas, and investigate the effects from different IPCC scenarios for future greenhouse gas emissions. The relative contribution of the 11-year solar cycle in UV flux to future stratospheric change will also be examined.